AR8622 UNIT I AIR CONDITIONING –PRINCIPLES AND SYSTEMS

Thermodynamics.

1.Thermodynamics

Thermodynamics is the branch of physics that deals with the relationships between heat and
other forms of energy.It deals with the mechanical action of heat.

First law of thermodynamics:

It states that energy can be changed from one form to another but can neither be created nor
destroyed.

Second law of thermodynamics:

 It is not possible for heat to flow from a colder body to a warmer body without
any work having been done to accomplish this flow. Energy will not flow spontaneously from a
low temperature object to a higher temperature object. Refrigerator runs in this principal.

Transfer of heat.

Heat can be transferred from one body to another or between a body and the environment by
three different means: conduction, convection and radiation.

Conduction is the transfer of energy through a solid material. Conduction between bodies

occurs when they are in direct contact, and molecules transfer their energy across the interface. 

Convection is the transfer of heat to or from a fluid medium. Molecules in a gas or liquid in
contact with a solid body transmit or absorb heat to or from that body and then move away,
allowing other molecules to move into place and repeat the process. Efficiency can be improved
by increasing the surface area to be heated or cooled, as with a radiator, and by forcing the fluid
to move over the surface, as with a fan.

Radiation is the emission of electromagnetic (EM) energy, particularly infrared photons that

carry heat energy. All matter emits and absorbs some EM radiation, the net amount of which
determines whether this causes a loss or gain in heat.
Refrigeration cycle components.

Mechanical
refrigeration is
accomplished by
continuously
circulating,
evaporating, and
condensing a fixed
supply of refrigerant
in a closed system.
All air conditioner
units must have the
five basic
components to
work:

1. The
compressor
2. The condenser
3. The expansion device
4. The evaporator
5. The copper refrigerant tube (a
tube that connects these air
conditioner parts)

In this refrigeration diagram, the four major

components split into two sections: Indoor
and Outdoor. In indoor units, we have the AC
parts number 1 and 2. In outdoor units, we
have the AC parts number 3 and 4. These four majors’ components are divided into two
difference pressure: high pressure and low pressure. The high pressure side is the condenser
units (outdoor) and the low pressure side is the air conditioning evaporator (indoor). The
divided point between high and low pressure cut through the compressor and the expansion
valve.

Evaporator- the cycle begins at the evaporator inlet, the low-pressure liquid expands, absorbs
heat from the indoor, and evaporates, changing into a low-pressure gas at the evaporator outlet.
The compressor pumps this gas from the evaporator
through the accumulator, increases its pressure, and
discharges the high-pressure gas to the condenser. The
accumulator is designed to protect the compressor by
preventing slugs of liquid refrigerant from passing directly into
the compressor. An accumulator should be included on all
systems subjected to varying load conditions or frequent
compressor cycling.

Accumulator

In the condenser, heat is removed from the gas, which then condenses and becomes a
high-pressure liquid. The condenser units are located outdoor with the compressor. It purposes
is to reject both sensible and latent heat of vapor absorb by the air conditioner units.The
condenser has three important steps:

1. Its remove sensible heat or (de-superheat)

2. Remove latent heat or (condense)
3. Remove more sensible heat or (subcooled)

Thermostatic Expansion Valve (TXV’s) or metering device is responsible for providing the
correct amount of refrigerant to the evaporator. This is done by creating a restriction within the
thermostatic expansion valve. The restriction causes the pressure and temperature of the
refrigerant entering the Evaporator to reduce.

TXV provides the correct amount

of refrigerant to the evaporator by using a
remote sensing bulb as a regulator. The
remote sensing bulb and capillary tube has
a refrigerant inside. As we can see in the
refrigeration cycle diagram above, the
remote sensing bulb is tie with the suction
line. The temperature from the suction line
transfer heat to the sensing bulb through
conduction. Sensing bulb responds to the
temperature of the suction line and as a
result, it decreases or increases the
temperature and pressure inside the sensing
bulb due to suction line temperatures.

Vapor compression cycle.

 Most common refrigeration cycle in use today, The major components of a
vapor-compression refrigeration system include the compressor, condenser, expansion
device, and evaporator. The latter three will be discussed in this clinic—the compressor is
discussed in a separate clinic.
This clinic will also discuss
many of the common
accessories used in a
comfortcooling refrigeration
system.

► There are four principal

control volumes involving
these components:

► Evaporator

► Compressor

► Condenser

► Expansion valve

All energy transfers by work and heat are taken as positive in the directions of the arrows on the
schematic and energy balances are written accordingly.

Refrigerant,

Every cyclic process requires an operating medium which in the refrigeration cycle is the
refrigerant. In the refrigeration cycle the refrigerant has the purpose of transporting heat. Here
the high absorption of energy during evaporation or discharge of energy during the
condensation of a liquid is utilised. To achieve this at the temperatures prevailing in a
refrigeration system at well manageable pressures, liquids with a low boiling point, such as
different fluorocarbons (FC), ammonia (NH3), carbon dioxide (CO2) or hydrocarbons such as
butane or propane, are used as operating medium.

Compressor,A compressor is a mechanical device that increases the pressure of a gas by

reducing its volume. An air compressor is a specific type of gas compressor. Compressors are
similar to pumps: both increase the pressure on a fluid and both can transport the fluid through a
pipe.
Condenser, In systems involving heat transfer, a condenser is a device or unit used to condense
a gaseous substance into a liquid state through cooling. In so doing, the latent heat is released by
the substance and transferred to the surrounding environment.

Evaporator, An evaporator is a device in a process used to turn the liquid form of a chemical
substance such as water into its gaseous-form/vapor. The liquid is evaporated, or vaporized, into
a gas form of the targeted substance in that process.

refrigerant control devices,

.Refrigerant Flow Control

1.To meter the liquid refrigerant from liquid line into the evaporator at a rate commensurate
with the rate at which vaporization of liquid is occurring in the later unit.

2. To maintain a pressure differential in the system to permit the refrigerant to vaporize at

desired low pressure in the evaporator while condensing at a high pressure in the condenser.

Refrigerant flow control devices include the following:

Automatic Expansion device

Thermostatic Expansion device

Thermal Electric Expansion device

Electronic Expansion device

High-side & Low-side float valves

Refrigerant control devices

THE THERMOSTAT
    Some refrigeration systems are designed to freeze product and/or keep it frozen.  Others are
designed to cool product and/or keep it cold — but definitely not freeze it.  Thermostats allow
refrigeration systems to bring product down to a predetermined temperature, but no lower than
that temperature. 
    Some refrigeration thermostats are similar to room thermostats in that they use a bimetallic
strip to sense temperature.  Others use a remote bulb filled with mercury or some volatile
liquid.  Still others sense temperature electronically. 
    Thermostats don’t often fail completely, but their internal calibration sometimes changes, and
other factors can affect their accuracy.  Thus, it is not safe to assume that the temperature
indicated on the thermostat dial is the actual temperature in the refrigerated space.  An accurate
thermometer should be used to monitor space temperature.
THE THERMOSTATIC EXPANSION VALVE (TXV)
    Illustrated below is a typical thermostatic expansion valve.  A TXV does two things.  First, it
acts as an expansion device for the refrigerant.  That is, it allows the liquid refrigerant to move
from the warm, high-pressure environment of the condenser output to the cold, low-pressure
environment of the evaporator input.  It does that by restricting the refrigerant flow in the same
way that a water tap restricts water flow when it is turned almost off.   In both cases liquid at
high pressure exists at the valve input, and liquid at low pressure exists at the output.
    The second function of the TXV is to regulate the amount of refrigerant that flows through
the evaporator.  Each TXV has its own temperature-sensing bulb that is clamped against the
refrigerant line leaving the evaporator.  Because liquid refrigerant can damage the compressor,
the refrigerant at the evaporator output must always be in gaseous form.  Each TXV is designed
for a particular refrigerant and a particular refrigeration load, and comes from the factory preset
to keep the refrigerant 7°F to 10°F above the vaporization temperature.  The TXV keeps the
temperature in this range by opening and closing in response
to bulb temperature.  When the temperature rises above the
setpoint, the valve opens wider and allows more refrigerant to
flow.  When it falls below the setpoint, the valve closes
somewhat and allows less to flow. 
    For the TXV to perform this critical job correctly, two
things have to be right:
1.      the TXV’s temperature-sensing bulb must be firmly
attached to the evaporator output tubing, and
2.      the TXV must be properly adjusted.
TXVs are quite reliable devices, are preset at the factory, and
do not normally require readjustment.  Thus, if the proper
evaporator superheat temperature is not being maintained,
look first for other problems.

DEFROST CONTROL
    Where cooling (not freezing) is the refrigeration goal, special defrosting equipment and
controls may not be needed.  Because the refrigerated space temperature is above freezing,
allowing the evaporator fans to run when the compressor is off may be all that is needed to
remove the frost.  Where freezing is the goal, however, heat from some source must be
periodically applied to the evaporator coil to melt the accumulated frost.
    Defrost cycles are often initiated by timers.  This is appropriate.  But using a timer to
establish the durationof the defrost period tends to waste energy.  Evaporator temperature is a
better indicator of when to stop defrosting.   To minimize energy cost, schedule the start of
defrosting with a time clock, but let temperature terminate it.
HEAD PRESSURE CONTROL
    Refrigeration systems operate best if the compressor head pressure remains within certain
limits.  The refrigeration condenser is sometimes situated out of doors and, if the compressor
fan continuously blows cold winter air through it, head pressure can drop to well below
optimum.  One solution is to use head pressure to turn the compressor fan on and off.  When
head pressure drops below a preset value, a pressure switch turns the fan off.  Low-pressure
control is also used in some systems to shut the system down in the event of refrigerant loss. 
High-pressure control is often used in systems with water-cooled condensers to shut the system
down in the event of cooling water loss.

air handling units,

Air handling units:

An air handler, or air handling unit, is a device used to regulate and circulate air as part of a
heating, ventilating, and air-conditioning (HVAC) system. An air handler is usually a large
metal box containing a blower, heating or cooling elements, filter racks or chambers, sound
attenuators, and dampers. Air handlers usually connect to a duct workventilation system that
distributes the conditioned air through the building and returns it to the AHU.

Small air handlers, for local use, are called terminal units, and may only include an air filter,
coil, and blower; these simple terminal units are called blower coils or fan coil units. A larger
air handler that conditions 100% outside air, and no recirculated air, is known as a makeup air
unit (MAU). An air handler designed for outdoor use, typically on roofs, is known as
a packaged unit(PU) or rooftop unit (RTU).

Some of the most known components are: -

Fans (Plug Fans, Double Inlet, Single Inlet, Axial, etc)
- Filters (Plate Filters, Bag Filters, Compact Filters, EPA Filters, HEPA Filters, ULPA Filters,
Carbon)
- Cooling/Heating Coils (water/steam/Direct Expansion DX/electric/gas fired)
- Heat recovery systems (cross flow plate heat exchangers, heat wheel/rotating heat exchangers,
run around coils and heat pipes, etc)
- Humidifiers (Adiabatic/Evaporative Pad, non-pressurized Steam, pressurized steam)
- Dehumidifiers (DX coil, desiccant rotor)
- Ultraviolet UV disinfection lamps
- Photocatalytic oxidation (PCO) air cleaners
- Sound attenuators- Mist/Droplet eliminators
- Dampers
15.electric motors

A motor is nothing but an electro-mechanical device that converts electrical energy to

mechanical energy. a device that produces rotational force is a motor. The very basic principal
of functioning of an electrical motor lies on the fact that force is experienced in the direction
perpendicular to magnetic field and the current, when field and current are made to interact with
each other.Classification of motor:

Cooling towers

basic cooling tower

Water, which has been heated by an industrial process or in an air-conditioning condenser, is

pumped to the cooling tower through pipes. The water sprays through nozzles onto banks of
material called "fill," which slows the flow of water through the cooling tower, and exposes as
much water surface area as possible for maximum air-water contact. As the water flows through
the cooling tower, it is exposed to air, which is being pulled through the tower by the electric
motor-driven fan.

When the water and air meet, a small amount of water is

evaporated, creating a cooling action. The cooled water is then
pumped back to the condenser or process equipment where it
absorbs heat. It will then be pumped back to the cooling tower to be cooled once again.

Natural draft cooling towers

As their name implies, natural draft cooling towers rely on natural convection to circulate air
throughout the tower, which then cools the water. Air movement occurs due to differences in
density between the entering air and the internal air within the tower. Warm, moist air, which is
more dense than cool air, will naturally rise through the tower, while the dry, cool air from
outside will fall, creating a constant cycle of air flow.

Mechanical draft cooling towers

Unlike natural draft cooling towers, mechanical draft cooling towers employ fans or other
mechanics to circulate air through the tower. Common fans used in these towers include
propeller fans and centrifugal fans. Mechanical draft towers are more effective than natural draft
towers, and can even be located inside a building when exhausted properly. However, they
consume more power than natural draft cooling towers and cost more to operate as a result.

Crossflow towers and counterflow towers are the two types of mechanical draft cooling towers:

1.Crossflow towe CWrs

In a crossflow tower, air flows horizontally through the cooling tower’s structure while hot
water flows downward from distribution basins. Crossflow towers can be as tall as counterflow
towers, but they’re also more prone to freezing and are less efficient.

2.Counterflow towers

Counterflow towers move air upward through the tower while water flows downward to cool
the air. These towers are often more compact in footprint than crossflow towers, and can save
energy in the long run.

Mechanical draft: which uses power driven fan motors to force or draw air through the tower.

-Induced draft Cooling Tower Design: A mechanical draft cooling

tower with a fan at the discharge which pulls air through tower. The
fan induces hot moist air out the discharge. This produces low
entering and high exiting air velocities, reducing the possibility of recirculation in which
discharged air flows back into the air intake.

-Forced draft Cooling Tower: A mechanical draft cooling tower

with a blower type fan at the intake. The fan forces air into the
tower, creating high entering and low exiting air velocities. The low
exiting velocity is much more susceptible to recirculation. With the
fan on the air intake, the fan is more susceptible to complications
due to freezing conditions. Another disadvantage is that a forced
draft design typically requires more motor power than the
equivalent induced draft design. The forced draft benefit is its
ability to work with high static pressure.

Air conditioning systems for buildings of different scales and their requirements- window type,
split system, package unit,

air conditioning system for small buildings

Air conditioning (often referred to
as A/C or AC) is the process of altering the
properties
of air (primarily temperature and humidity) to
more comfortable conditions, typically with the
aim of distributing the conditioned air to an
occupied space such as a building to
improve thermal comfort and indoor air quality.
In common use, an air conditioner is a device
that lowers the air temperature. Thecooling is
typically achieved through a refrigeration cycle,
but sometimes evaporation or free cooling is
used.

A,Window type:
These types of AC are designed to be fitted in window sills. A single unit of Window Air
Conditioner houses all the necessary components, namely the compressor, condenser, expansion
valve or coil, evaporator and cooling coil enclosed in a single box. Since a window AC is a
single unit, it takes less effort to install as well as for maintenance.They are available up to 2
tons.

Advantages:
o Single unit air conditioner
o Less effort needed for installation
 o Costs lesser in comparison to other varieties

B,Evaporative cooler: 
An evaporative cooler (also swamp cooler, desert cooler and wet air cooler) is a device that
cools air through the evaporation of water. Evaporative cooling differs from typical air
conditioning systems which use vapor-compression or absorption refrigeration cycles.
Evaporative cooling works by employing water's large enthalpy of vaporization. The
temperature of dry air can be dropped significantly through the phase transition of liquid water
to water vapor (evaporation), which can cool air using much less energy than refrigeration. In
extremely dry climates, evaporative cooling of air has the added benefit of conditioning the air
with more moisture for the comfort of building occupants.

Advantages:
o Do not use
refrigerants
o Consume less
energy,
o Less expensive to
install,
o Less expensive to
operate
o Suitable for dry
area as
Conditioned air has more moisture

C, Packaged terminal units

This type of air conditioner is used if you want to cool more than two rooms or a larger space at
your home or office. There are two possible arrangements with the package unit. In the first
one, all the components, namely the compressor, condenser (which can be air cooled or water
cooled), expansion valve and evaporator are housed in a single box. The cooled air is thrown by
the high capacity blower, and it flows through the ducts laid through various rooms. In the
second arrangement, the compressor and condenser are housed in one casing. The compressed
gas passes through individual units, comprised of the expansion valve and cooling coil, located
in various rooms. The packaged air conditioners are used for the cooling capacities in between
these two extremes. The packaged air conditioners are available in the fixed rated capacities of
3, 5, 7, 10 and 15 tons. These units are used commonly in places like restaurants, telephone
exchanges, homes, small halls, etc.
Types: Package AC with Water Cooled Condenser and Package Air Conditioner Air Cooled
Condenser.
D,Split AC:
The split air conditioner comprises of two parts: the outdoor unit
and the indoor unit. The outdoor unit, fitted outside the room, houses
components like the compressor, condenser and expansion valve. The
indoor unit comprises the evaporator or cooling coil and the cooling
fan. For this unit you don’t have to make any slot in the wall of the
room. Further, present day split units have aesthetic appeal and do
not take up as much space as a window unit. A split air conditioner
can be used to cool one or two rooms. They can provide up to 5tons.
Advantages
● Internal unit takes up less space for installation
● Usually more silent than window ACs
● Minimally affect your home decor
● Can be installed in room with no windows
direct expansion system, chilled water system,
DX system:
A direct expansion air conditioning (DX) system uses a
refrigerant vapour expansion/compression (RVEC) cycle to
directly cool the supply air to an occupied space. DX systems
(both packaged and split) directly cools the air supplied to the building because the evaporator
is in direct contact with the supply air.
In the direct expansion or DX types of air central conditioning plants the air used for cooling
space is directly chilled by the refrigerant in the cooling coil of the air handling unit. Since the
air is cooled directly by the refrigerant the cooling efficiency of the DX plants is higher.
However, it is not always feasible to carry the refrigerant piping to the large distances hence,
direct expansion or the DX type of central air conditioning system is usually used for cooling
the small buildings or the rooms on the single floor.
There are three main compartments of the DX type of central conditioning systems (please refer
the fig below):
 a) The Plant Room:
The plant room comprises of the important parts of the refrigeration system, the compressor and
the condenser. The compressor can be either semi-hermetically sealed or open type. The
semi-hermetically sealed compressors are cooled by the air, which is blown by the fan, while
open type compressor is water cooled. The open compressor can be driven directly by motor
shaft by coupling or by the belt via pulley arrangement.The condenser is of shell and tube type
and is cooled by the water. The refrigerant flows along the tube side of the condenser and water
along the shell side, which enables faster cooling of the refrigerant. The water used for cooling
the compressor and the condenser is cooled in the cooling tower kept at the top of the plant
room, though it can be kept at other convenient location also.
b) The Air Handling Unit Room:
The refrigerant leaving the condenser in the plant room enters the thermostatic expansion valve
and then the air handling unit, which is kept in the separate room. The air handling unit is a
large box type of unit that comprises of the evaporator or the cooling coil, air filter and the
large blower. After leaving the thermostatic expansion valve the refrigerant enters the cooling
coil where it cools the air that enters the room to be air conditioned. The evaporator in the air
handling unit of the DX central air conditioning system is of coil type covered with the fins to
increasing the heat transfer efficiency from the refrigerant to the air.
There are two types of ducts connected to the air handling unit: for absorbing the hot return air
from the rooms and for sending the chilled air to the rooms to be air conditioned. The blower of
the air handling unit enables absorbing the hot return air that has absorbed the heat from the
room via the ducts. This air is then passed through the filters and then over the cooling coil.
The blower then passes the chilled air through ducts to the rooms that are to be air conditioned.
The DX expansion system runs more efficiently at higher loads. Even in case of the breakdown
of the plants, the other plants can be used for the cooling purpose. The DX types of central
air conditioner plants are less popular than the chilled water type of central conditioning plants.
c) Air Conditioned Room:
This is the space that is to be actually cooled. It can be residential room, room of the hotel, part
of the office or any other suitable application. The ducts from the air handling room are passed
to all the rooms that are to be cooled. The ducts are connected to the grills or diffusers that
supply the chilled air to the room. The air absorbs the heat and gets heated and it passes through
another set of the grill and into the return air duct that ends into the air handling unit room. This
air is then re-circulated by the air handling unit.
Though the efficiency of the DX plants is higher, the air handling units and the refrigerant
piping cannot be kept at very long distance since there will be lots of drop in pressure of the
refrigerant along the way and there will also be cooling losses. Further, for the long piping,
large amounts of refrigerant will be needed which makes the system very expensive and also
prone to the ma instance problems like the leakage of the refrigerant.

Due to these reasons the DX type central air conditioning systems are used for small air
conditioning systems of about 5 to 15 tons in small buildings or the number of rooms on a
single floor. If there are large air conditioning loads, then multiple direct expansion systems can
be installed. In such cases, when there is lesser heat load one of the plants can be shut down and
the other can run at full load. The DX expansion system runs more efficiently at higher loads.
Even in case of the breakdown of the plants, the other plants can be used for the cooling
purpose. The DX types of central air conditioning plants are less popular than the chilled water
type of central conditioning plants.
Benefits

● DX systems are less expensive to install, and uses less space in mechanical and electrical
rooms than centralized cooling systems
● DX systems can be expanded in an incremental fashion to match changing building
requirements
● Packaged Systems have standardized operating performances per unit, allowing more
precise system sizing
● Packaged Systems generally require less ventilation, and do not require dedicated
condensate lines
● Packaged Systems occupy less space than comparable split systems
● Split Systems tend to be larger allowing for fewer units, and therefore less maintenance
costs than a comparable Packaged system
● Split Systems have lower noise levels because the compressor unit is located further away
from the cooling load area
● Split Systems may allow vertical duct shafts to be smaller in size.

3.chilled water system:

the chilled water types of central air conditioning plants are installed in the place where whole
large buildings, shopping mall, airport, hotel, etc, comprising of several floors are to be air
conditioned. While in the direct expansion type of central air conditioning plants, refrigerant is
directly used to cool the room air; in the chilled water plants the refrigerant first chills the water,
which in turn chills the room air.
In chilled water plants, the ordinary water or brine solution is chilled to very low temperatures
of about 6 to 8 degree Celsius by the refrigeration plant. This chilled water is pumped to various
floors of the building and its different parts. In each of these parts the air handling units are
installed, which comprise of the cooling coil, blower and the ducts. The chilled water flows
through the cooling coil. The blower absorbs return air from the air conditioned rooms that are
to be cooled via the ducts. This air passes over the cooling coil and gets cooled and is then
passed to the air conditioned space.
various Parts of the Chilled Water Air Conditioning Plant
a) Central Air Conditioning Plant Room:
The plant room comprises of all the important components of the chilled water air conditioning
plant. These include the compressor, condenser, thermostatic expansion valve and
the evaporator or the chiller. The compressor is of open type and can be driven by the motor
directly or by the belt via pulley arrangement connected to the motor. It is cooled by the water
just like the automotive engine.
condenser and the evaporator are of shell and tube type. The condenser is cooled by the water,
with water flowing along the shell side and refrigerant along the tube side.The thermostatic
expansion valve is operated automatically by the solenoid valve.
The evaporator is also called as the chiller, because it chills the water. If the water flows along
the shell side and refrigerant on the tube side, it is called as the dry expansion type of chiller. If
the water flows along tube side and the refrigerant along the shell side, it is called as the
flooded chiller. The water chilled in the chiller is pumped to various parts of the building that
are to be air conditioned. It enters the air handling unit, cools the air in cooling coil, absorbs the
heat and returns back to the plant room to get chilled again. The amount of water passing into
the chiller is controlled by the flow switch.
In the central air conditioning plant room all the components, the compressor, condenser,
thermostatic expansion valve, and the chiller are assembled in the structural steel framework
making a complete compact refrigeration plant, known as the chiller package. Piping required to
connect these parts is also enclosed in this unit making a highly compact central
air conditioning plant.
The air handling units are installed in the various parts of the building that are to be air
conditioned, in the place called air handling unit rooms. The air handling units comprise of the
cooling coil, air filter, the blower and the supply and return air ducts. The chilled water flows
through the cooling coil. The blower absorbs the return hot air from the air conditioned space
and blows it over the cooling coil thus cooling the air. This cooled air passes over the air filter
and is passed by the supply air ducts into the space which is to be air conditioned. The air
 handling unit and the ducts passing through it are insulated to reduce the loss of the cooling
effect.
b) Air Handling Unit Rooms:
The air handling units are installed in the various parts of the building that are to be air
conditioned, in the place called air handling unit rooms. The air handling units comprise of the
cooling coil, air filter, the blower and the supply and return air ducts. The chilled water flows
through the cooling coil. The blower absorbs the return hot air from the air conditioned space
and blows it over the cooling coil thus cooling the air. This cooled air passes over the air filter
and is passed by the supply air ducts into the space which is to be air conditioned. The air
handling unit and the ducts passing through it are insulated to reduce the loss of the cooling
effect.
c) Air Conditioned Rooms:
These are the rooms or spaces that are to be air conditioned. These can be residential or hotel
rooms, halls, shops, offices, complete theater, various parts of the airport etc. At the top of these
rooms the supply and the return air ductsare laid. The supply air ducts supply the cool air to the
room via one set of the diffusers, while the return air ductsabsorbs the hot return air from the
room by another set of the diffusers. The hot return air enters the air handling unit, gets cooled
and again enters the room via supply duct to produce air conditioning effect.fan coil unit,
A fan coil unit (FCU), also known as a Vertical Fan Coil-Unit (VFC), is a simple device
consisting of a heating and/or cooling heat exchanger
or 'coil' and fan. It is part of an HVAC system found in
residential, commercial, and industrial buildings. A fan
coil unit is a diverse device sometimes using ductwork,
and is used to control the temperature in the space
where it is installed, or serve multiple spaces. It is
controlled either by a manual on/off switch or by a
thermostat, which controls the throughput of water to
the heat exchanger using a control valve and/or the fan
speed.

district cooling systems.

Chillers in a district cooling at University of Rochester in Rochester, New York.

District cooling is the cooling equivalent of district heating. Working on broadly similar
principles to district heating, district cooling delivers chilled water to buildings like offices and
factories needing cooling. In winter, the source for the cooling can often be sea water, so it is a
cheaper resource than using electricity to run compressors for cooling. Alternatively, District
Cooling can be provided by a Heat Sharing Network which enables each building on the circuit
to use a heat pump to reject heat to an ambient ground temperature circuit
Energy efficient systems,

environmental aspects and latest innovations. Understanding all the above through product
literature/ field visits
UNIT II DESIGN ASPECTS OF AIRCONDITIONING SYSTEMS 10

Design criteria for selection of air conditioning. Configuring/ sizing of mechanical

equipment,equipment and spaces for them. Horizontal and vertical distribution of services for large
buildings.Exercise on the above through choice, calculations, layout, drawings.

1.Design criteria for selecting the Air conditioning system for large building

Performance requirements: One important function of the system selection process is helping the designer
and the owner to share the same performance expectations. No matter how attractive other aspects of a
possible system might be, you cannot seriously consider a system that will not meet the stated performance
criteria. However, you can explain to the owner that by accepting these conditions instead of those conditions,
the owner will gain that benefit.

Capacity Requirements: If it takes x cfm at y temperature to maintain the stated indoor design conditions at
the outdoor design conditions, the designer does not have a choice. He must provide a system that can deliver
the conditions he says it will deliver. However, different system types may require different total building
capacities to achieve the same end results. When the owner asks, “Can’t we make this system less
expensive?” he must understand that the system capacity can only be reduced if he is willing to accept less
stringent indoor conditions at least part of the time. Zoning is a popular target for reducing first cost. The owner
needs to understand that reducing control zoning might make areas uncomfortable for thousands of hours of
each year, while reducing peak capacity might make areas uncomfortable for 100 or 200 hours each year

Spatial Requirements: Simply stated, the recommended system has to fit in the space available in the
building. No matter how reliable, how inexpensive to own and operate, how quiet, if it does not fit, you cannot
use it. However, it is possible to discuss with the architect and the owner the advantages to the project if more
space is made available for the HVAC system, or if the space can be arranged differently to accommodate
certain features in the HVAC system.

First Cost: “Spend as much as necessary to achieve the performance, but no more.” Easy to say, but difficult
to know if you are doing it. First cost is probably the first criterion that comes to mind, and it iscertainly
important. For some owners, it might even seem to be the only criterion. But there are other criteria, and some
of them will have a bigger effect on total costs over the life of the building than first cost.

Operating Cost: Operating cost is made up of many components. Energy, water and sewer, maintenance,
repair, equipment replacement, and system modifications are the most common. Many of them will be
determined directly by which system is selected. The tradeoff between operating cost and first cost is obvious
and familiar. However, operating cost is also affected by less direct factors such as accessibility for
maintenance.

Reliability: How reliable is reliable enough? Certainly an owner will be much more attuned to avoiding
downtime for a mainframe computer room, a network hub, or a clean room than he would be for a restaurant or
an apartment building, and rightfully so. Reliability should consider how quickly and easily service can be
restored in the event of a failure as well as how frequently failures are likely to occur. The system type affects
both.

Flexibility: Years ago, office buildings had large spaces with row upon row of desks. People came and went,
but the physical arrangement rarely changed. Today, with project teams and rapidly evolving technology,
nothing stays the same for long. When the layout changes to accommodate a new tenant or a new
department, or when new equipment is installed that needs special conditioning, how easily can the HVAC
system be adapted to meet that new need?

Maintainability: What will it take to keep the system in good operating condition, and running smoothly and
efficiently? Will periodic maintenance entail mechanics working in the occupied space or in a mechanical
room? Will someone be climbing on a desktop every few months to change filters? What level of skill will be
required to operate and maintain the system? Will the owner need to hire one or more skilled operators, or can
the proposed system run effectively unattended?
 design information needed.

2.Horizontal distribution of services for large buildings

Service duct require careful planning and should be considered at an early stage in the design of a
building.Accommodation of the plant and the layout of services are the two essential factors in design.It is
usual to need some 7 – 10% of the total floor area for plant spaces and ducts.

The purpose :

conceal the services and to facilitate inspection, repair and alterations.

Helps to reduce noise

 Protects the services from damage

• Plant space – area required for the accommodation of mechanical or electrical equipment or
control gear required for the operation of services
• Storage space – area required for the accommodation of storage containers required for
particular services
• Duct – space within a building specially enclosed for the accommodation of services and
allowing facilities for working and inspection.
• Subway – a horizontal passage for the conveyance of services underground or below the
bottom floor of the building which allows walking headroom for access.
• Crawlway – passage for services similar to a subway but where there is insufficient headroom
to stand upright.
• Trench – horizontal passage for services below floor level where the access is by removable
covers in the floor.
• Wells – vertical space used for the accommodation of stairs or lifts or to allow natural light or
ventilation
• Casing – an enclosure formed over pipes or cables running on the surface of a wall or ceiling.
Casing are usually for decoration but can also provide protection from impact or corrosion.
• Chase – a recess cut in a wall or floor when building is over; it accommodates pipes or cables
and is screed or plastered over
• Void – space may used for the accommodation of services but which is not primarily for this
purpose

4.Rised access floors

A raised floor (also raised flooring, access floor(ing),) provides an elevated structural floor above a solid

substrate (often a concrete slab) to create a hidden void for the passage of mechanical and electrical services.
Raised floors are widely used in modern office buildings, and in specialized areas such as command
centers, IT data centers and computer rooms, where there is a requirement to route mechanical services and
cables, wiring, and electrical supply. Such flooring can be installed at varying heights from 2 inches (51 mm) to
heights above 4 feet (1,200 mm) to suit services that may be accommodated beneath. Additional structural
support and lighting are often provided when a floor is raised enough for a person to crawl or even walk
beneath.
Horizontal distribution system:
1. Through ceiling:
 Diffusers are provided in ceiling to distribute the conditioned air into the room.
Diffusers are very common in heating, ventilating, and air-conditioning systems.[1] Diffusers are used on both
all-air and air-water HVAC systems, as part of room air distribution subsystems, and serve several purposes:

● To deliver both conditioning and ventilating air

● Evenly distribute the flow of air, in the desired directions
● To enhance mixing of room air into the primary air being discharged
● Often to cause the air jet(s) to attach to a ceiling or other surface, taking advantage of the Coandă effect
● To create low-velocity air movement in the occupied portion of room
● Accomplish the above while producing the minimum amount of noise.
2. through floor:
 An air conditioning floor of the floor blowing type, which provides a comfortable office space.
A mild airflow is blown from a raised floor via air conditioning systems installed within the underfloor space,
which has been secured for wiring to date.
 PRIME
COLLEGE OF ARCHITECTURE AND PLANNING
Kilvelur, Nagapattinam District, Tamil Nadu State, Pin Code - 611104.
Landline : 04366 – 276177, Email : primearch2010@gmail.com

AR8622

Building services III

ANNA UNIVERSITY, CHENNAI

AFFILIATED INSTITUTIONS

R – 2017

B.ARCH. DEGREE PROGRAMME

AR8622 |BUILDING SERVICE III |2017 REGULATION|A.SIVARAMAN M.ARCH|PRIME CAP-KILVELUR 1

 BUILDING SERVICES III
AR8622 L T P/S C
20 2 3
OBJECTIVES
 To give exposure to the science behind air-conditioning systems, the different types and
applications.
 To enable understanding of architectural aspects related to air-conditioning systems and
take appropriate design decisions.
 To inform about fire protection, fire safety and fire fighting in buildings and how to plan for
the Same.
 To inform about mechanical transportation systems for buildings and how to plan for the
same.

UNIT I AIR CONDITIONING – PRINCIPLES AND SYSTEMS 14

Part :01

 Thermodynamics.
 Transfer of heat.
 Refrigeration cycle components.
 Vapor compression cycle.
-Refrigerant, -Compressor, -Condenser,
-Evaporator, -Refrigerant control devices, -Electric motors,
-Air handling units, -Cooling towers.
Part :02
Air conditioning systems for buildings of different scales and their requirements
-Window type, -Split system, - package unit,
-Direct expansion system, -Chilled water system, - fan coil unit,
-District cooling systems. -Energy efficient systems, - environmental
aspects
…………………………………………………………………………………………………………………and latest
innovations.
Understanding all the above through product literature/ field visits.
UNIT II DESIGN ASPECTS OF AIRCONDITIONING SYSTEMS 10
Part :01 Design criteria for selection of air conditioning. Configuring/ sizing of mechanical
equipment and spaces for them.
Part :02 Horizontal and vertical distribution of services for large buildings.
Exercise on the above through choice, calculations, layout, drawings.

AR8622 |BUILDING SERVICE III |2017 REGULATION|A.SIVARAMAN M.ARCH|PRIME CAP-KILVELUR 2

UNIT III FIRE AND SAFETY 12
Part :01 Causes of fire in buildings. Stages of fire and how it spreads. Fire drill. Heat/ fire/
smoke detection.
Part :02 Alarm and extinguisher systems. Fire safety standards. General guidelines for
egress design for multistory buildings.
Understanding all the above through product literature/ field visits. Exercise on design of fire
safety systems for different building types through choice, calculations, layout and drawings.
UNIT IV MECHANICAL TRANSPORTATION SYSTEMS IN BUILDINGS 12
Part :01
Lifts and escalators - types and applications. Round trip time for lifts. Design of lift lobby
and vertical transportation core.
Part :02
Conveyors, travelators, dumb waiters. Standards for all.
Latest technologies in vertical transport systems.
Integration of lifts and escalators with building automation systems.
Understanding all the above through product literature/ field visits. Design exercise on the above
through choice, calculations, layout and drawings
UNIT V INTEGRATION OF SERVICES INTO ARCHITECTURAL DESIGN 12
Principles of grouping and integrating of horizontal and vertical distribution of all services in a
multistoreyed building/large building. Services to include vertical transportation, electrical,
communication, air conditioning and fire safety .
Integrating service requirements into architectural design in an appropriate typology involving a
simple scale project through sketches/ drawings.
TOTAL: 60 PERIODS
OUTCOME
 Familiarity with different air conditioning systems, their context of use and basics of
planning involved.
 An understanding of fire safety, fire fighting, fire prevention and installations in buildings.
 An understanding of mechanical transportation systems in a building.
 Ability to integrate services in buildings.
TEXTBOOKS
1. William H. Severns and Julian R Fellows, 'Air conditioning and Refrigeration', John Wiley and
Sons, London, 1988.
2. National Building Code - Bureau of Indian Standards.
3. 'ISHRAE Handbook for Refrigeration', 2015.
4. George R. Strakosch (Editor), Robert S. Caporale, 'The Vertical Transportation Handbook- 4th
Edition, Wiley and Sons, 2010.
5. David Lee Smith, 'Environmental Issues for Architecture', Wiley, 2011.

AR8622 |BUILDING SERVICE III |2017 REGULATION|A.SIVARAMAN M.ARCH|PRIME CAP-KILVELUR 3

REFERENCES
1. A.F.C. Sherratt, 'Air Conditioning and Energy Conservation', The Architectural Press, London,
1980.
2. Andrew H Buchanan; 'Structural Design for Fire Safety', Wiley, 2001.
3. Swenson S. Don, 'Heating, Ventilating and Air Conditioning', American Technical Publishers,
1995.
4. ISHRAE, 'All about AHUs- Air Handling Units'.
5. CIBSE Guide D, 'Transportation Systems in Buildings',2010.
6. A.K.Mittal, 'Electrical and Mechanical Services in High Rise Building: Design and Estimation
Manual', CBS, 2009.

AR8622 |BUILDING SERVICE III |2017 REGULATION|A.SIVARAMAN M.ARCH|PRIME CAP-KILVELUR 4

UNIT I AIR CONDITIONING – PRINCIPLES AND SYSTEMS .

1.1 . THERMODYNAMICS
Thermodynamics is the branch of science concerned with heat and temperature and their relation
to energy and work. Thermo means Heat and Dynamics means Work.

Law of Thermodynamics

The four laws of Thermodynamics summarize the most important facts of thermodynamics. They
define fundamental physical quantities such as temperature, energy and entropy, in order to
describe thermodynamic systems. They also describe the transfer of energy as heat and work in
thermodynamic processes.
Zeroth Law:
 The Zeroth law of thermodynamics recognizes that if two systems are in thermal
equilibrium with a third, they are also in thermal equilibrium with each other, thus
supporting the notion of temperature and heat.


First Law:
 The first law of thermodynamics distinguishes between two kinds of physical process,
namely energy transfer as work and energy transfer as heat.


Second Law:
 The second law of thermodynamics distinguishes between reversible and irreversible
physical processes.

AR8622 |BUILDING SERVICE III |2017 REGULATION|A.SIVARAMAN M.ARCH|PRIME CAP-KILVELUR 5

 

Third Law:
 The third law of thermodynamics concerns the entropy of a perfect crystal at absolute zero
temperature, and implies that it is impossible to cool a system to exactly absolute zero,
or equivalently that perpetual motion machines of the third kind are impossible.

1.2 . Transfer of heat.

HEAT
 Heat is a form of energy. We feel only this. we don’t see this one by eyes. That is,
we really
think of temperature instead of heat, for it is temperature that we recoginse that
an object as heat in it. Temperature is an concentration value of the heat.
 Heat transfer is a discipline of thermal engineering that concerns the generation,
use, conversion, and exchange of thermal energy (heat) between physical
systems.
 Heat transfer is classified into various mechanisms, such as thermal
conduction, thermal convection, thermal radiation, and transfer of energy
by phase changes.
UNITS OF HEAT
 B.T.U. BRITISH THERMAL UNIT. IN this defined as the amount of heat added to raise

AR8622 |BUILDING SERVICE III |2017 REGULATION|A.SIVARAMAN M.ARCH|PRIME CAP-KILVELUR 6

 the temperature of one pound of water by one degree FAHRENHEIT.
 C.G.S CALORIE IN THE METRIC
the amount of heat added to raise the temperature of one gram of water by one degree
celsius. As calorie is a small unit, kilocalorie is used.
1kilo calorie=1000 calories
1kilo calorie=3.97 BTU
TEMPERATURE
Temperature is a measure of the internal kinetic energy of an object. Temperature is an
indication level of heat in a substance. A substance at the temperature of 10 degree Celsius
has more heat in it than the same substance at a Temperature of 0 degree Celsius. The
Temperature of a substance, however does not given an idea of the amount of heat the
substance has.
Measuring Instrument : Thermometer
Scale : Fahrenhit and Celsius
THE FUNDAMENTAL MODES OF HEAT TRANSFER ARE:
 Advection
Advection is the transport mechanism of a fluid from one location to another, and is
dependent on motion and momentum of that fluid.
 Conduction or diffusion
The transfer of energy between objects that are in physical contact. Thermal
conductivity is the property of a material to conduct heat and evaluated primarily in terms
of Fourier's Law for heat conduction.
 Convection
The transfer of energy between an object and its environment, due to fluid motion. The
average temperature is a reference for evaluating properties related to convective heat
transfer.
 Radiation
The transfer of energy by the emission of electromagnetic radiation.

PHASE CHANGE MECHANISM

LATENT HEAT
 Latent heat is energy released or absorbed, by a body or a thermodynamic system, during
a constant-temperature process — usually a first-order phase transition.
 Latent heat can be understood as energy in hidden form which is supplied or extracted to
change the state of a substance without changing its temperature. Examples are latent

AR8622 |BUILDING SERVICE III |2017 REGULATION|A.SIVARAMAN M.ARCH|PRIME CAP-KILVELUR 7

 heat of fusion and latent heat of vaporization involved in phase changes, i.e. a substance
condensing or vaporizing at a specified temperature and pressure.
Expressions of PHASE CHANGE :
Phase changes to a more energetic state include the following:
 Melting—Solid to liquid
 Vaporization—Liquid to gas (included boiling and evaporation)
 Sublimation—Solid to gas
Phase changes to a less energetic state are as follows:
 Condensation—Gas to liquid
 Freezing—Liquid to solid

 LATENT HEAT OF FUSION

During the State Changes Like, SOLID to LIQUID the Temperature remains constant. It
requires
great deal of heat energy for this change of state , and the quality of heat need for the
change is
called latent heat of fusion.
 LATENT HEAT OF EVAPORATION
During the State Changes Like, LIQUID to GAS the Temperature remains constant. It
requires great
deal of heat energy for this change of state , and the quality of heat need for the change is
called
latent heat of Evaporation.

1..3 REFRIGERATION CYCLE COMPONENTS

COMPRESSOR CONDENSER THERMAL EXPANSION

VALVE EVAPORATOR
The refrigeration cycle contains four major components: the compressor, condenser, expansion
device, and evaporator. Refrigerant remains piped between these four components and is
contained in the refrigerant loop.

AR8622 |BUILDING SERVICE III |2017 REGULATION|A.SIVARAMAN M.ARCH|PRIME CAP-KILVELUR 8

The refrigerant begins as a cool vapor and heads to the first component: the compressor. The
compressor is widely considered the engine of the refrigeration cycle; it consumes the most power
out of the HVAC system’s components and forces the refrigerant through the system. In the
process of being compressed the cool, gaseous refrigerant is turned to a very hot and high-
pressure vapor.

Fig: Refrigeration Cycle

SOURCE: https://blog.ravti.com/knowledge-refrigeration-cycle-d666a719d154
NOTE: Whether it is in an AC or refrigerator, the principles of the cycle remain the same.

After compression, the refrigerant moves to the next component in the refrigeration cycle: the
condenser.

The condenser’s job is to cool the refrigerant so that it turns from a gas into a liquid, or
condenses. This happens when warm outdoor air is blown across the condenser coil that is filled
with hot, gaseous refrigerant. This allows heat to transfer from the refrigerant to the cooler
outdoor air, where the excess heat is rejected to the atmosphere. The condenser coils wind
through the condenser to maximize the surface area of the piping, and effectively, the heat
transfer to the air. The refrigerant turns from a vapor into a hot liquid due to the high pressure
and reduction in temperature.

The refrigerant is now approaching the expansion device as a hot, high-pressure liquid. The
expansion device is responsible for quickly driving the pressure of the refrigerant down so it can
boil (evaporate) more easily in the evaporator — and that’s it! The expansion device has one sole
purpose: to reduce refrigerant pressure. Because the pressure drops so rapidly at the expansion
device, the refrigerant turns into a combination of a cold liquid and vapor.

AR8622 |BUILDING SERVICE III |2017 REGULATION|A.SIVARAMAN M.ARCH|PRIME CAP-KILVELUR 9

Now that the refrigerant is a cold mix of liquid and gas (vapor), it begins to move through
the evaporator. The evaporator is responsible for cooling the air going to the space by boiling
(evaporating) the refrigerant flowing through it. This happens when warm air is blown across the
evaporator as cold refrigerant moves through the evaporator coil. Heat transfers from the air to
the refrigerant, which cools the air directly before it is vented to the space. Like the condenser
coil, the evaporator coil also winds through the evaporator to maximize heat transfer from the
refrigerant to the air. The low-pressure liquid refrigerant is easily boiled by the warm air blown
across the evaporator and heads back to the compressor as a cool gas/vapor.

Fig: Concept of Refrigeration Cycle

SOURCE: https://blog.ravti.com/knowledge-refrigeration-cycle-d666a719d154

NOTE: The refrigerant is hottest when it leaves the compressor and coldest when it leaves the
expansion device.
To summarize
— heat is absorbed by the refrigerant (cooling the air) in the evaporator and expelled from
the refrigerant to the outdoor air in the condenser. Simultaneously, the expansion device and
compressor help us manipulate the pressure of the refrigerant to make the cycle possible.

1.4 Vapor compression cycle.

The Vapor Compression Refrigeration Cycle is nearly 200 years old, but it does not seem ready
to leave the scene any time soon. While some people have viewed this method as
environmentally harmful and inefficient, the cycle is still applicable in the industrial sphere.

Natural gas plants, petroleum refineries, and petrochemical plants and most of the food and
beverage processes are some of the industrial plants that utilize vapor compression
refrigeration systems.

AR8622 |BUILDING SERVICE III |2017 REGULATION|A.SIVARAMAN M.ARCH|PRIME CAP-KILVELUR 10

What is its defining feature of these systems?

The simplest explanation of this system is a heat engine working in reverse, technically
referred to as reverse Carnot engine. In other words, it is the transfer of heat from a cold
reservoir to a hot one. Clausius Statement of the Second Law of thermodynamics states:

“It is impossible to construct a device that operates in a cycle and produces no effect other
than the transfer of heat from a lower-temperature body to a higher-temperature body”.

Since the vapor compression cycle is against the Second Law of Thermodynamics, some work
is necessary for the transfer to take place.

The Vapor Compression Refrigeration Cycle involves four components: compressor,

condenser, expansion valve/throttle valve and evaporator.

It is a compression process, whose aim is to raise the refrigerant pressure, as it flows from an
evaporator. The high-pressure refrigerant flows through a condenser/heat exchanger before
attaining the initial low pressure and going back to the evaporator.

A more detailed explanation of the steps is as explained below.

STEP 1: COMPRESSION

The refrigerant (for example R-717) enters the compressor at low temperature and low
pressure. It is in a gaseous state. Here, compression takes place to raise the temperature
and refrigerant pressure. The refrigerant leaves the compressor and enters to the
condenser.

Since this process requires work, an electric motor may be used. Compressors themselves
can be scroll, screw, centrifugal or reciprocating types.

STEP 2: CONDENSATION

The condenser is essentially a heat exchanger. Heat is transferred from the refrigerant to
a flow of water. This water goes to a cooling tower for cooling in the case of water-cooled
condensation.

Note that seawater and air-cooling methods may also play this role. As the refrigerant
flows through the condenser, it is in a constant pressure.

AR8622 |BUILDING SERVICE III |2017 REGULATION|A.SIVARAMAN M.ARCH|PRIME CAP-KILVELUR 11

 One cannot afford to ignore condenser safety and performance. Specifically, pressure
control is paramount for safety and efficiency reasons. There are several pressure-
controlling devices to take care of this requirement

STEP 3: THROTTLING AND EXPANSION

When the refrigerant enters the throttling valve, it expands and releases
pressure. Consequently, the temperature drops at this stage. Because of these changes,
the refrigerant leaves the throttle valve as a liquid vapor mixture, typically in proportions
of around 75 % and 25 % respectively.

Throttling valves play two crucial roles in the vapor compression cycle. First, they maintain
a pressure differential between low- and high-pressure sides. Second, they control the
amount of liquid refrigerant entering the evaporator

STEP 4: EVAPORATION

At this stage of the Vapor Compression Refrigeration Cycle, the refrigerant is at a lower
temperature than its surroundings. Therefore, it evaporates and absorbs latent heat of
vaporization.

Heat extraction from the refrigerant happens at low pressure and temperature.
Compressor suction effect helps maintain the low pressure.

There are different evaporator versions in the market, but the major classifications are
liquid cooling and air cooling, depending whether they cool liquid or air respectively.

Fig 1: Schematic Representation of the Steps

AR8622 |BUILDING SERVICE III |2017 REGULATION|A.SIVARAMAN M.ARCH|PRIME CAP-KILVELUR 12

 SOURCE: https://www.araner.com/blog/vapor-compression-refrigeration-cycle/

PROBLEMS IN THE VAPOR COMPRESSION CYCLE

The Coefficient of Performance (COP) expresses the efficiency of this cycle. Knowing that the aim
of the refrigerator is heat removal and that this process requires work, the COP of the cycle
becomes:
Where “h” is the enthalpy in the system.
Some of the Vapor Compression Refrigeration Cycle Problems that may affect this value are:
 COMPRESSOR LEAKAGE/FAILURE
The failure of an industrial refrigeration compressor can be expensive affair to the company
and damaging to the manufacturer’s reputation. Often, manufacturers will tear down returned
compressors in search faults. Over years of studies, some common reasons for compressor
failure have been identified to include lubrication problems, overheating, slugging, flood back
and contamination.

 FOULING – EVAPORATOR AND CONDENSER

Fouling is any insulator hinders transfer between the water and the refrigerant.

It could result from algae growth, sedimentation, scale formation or slime. As this problem
increases head pressure, it can lead to increased energy use by the compressor. What is the
best practice?

 Keep the evaporator surface and condenser tubes clean.

Water treatment practices need to be on point to keep this problem at bay.

 MOTOR COOLING
The motor is easily the highest energy consumer in the vapor compression cycle. Most times
when efficiency drops in this device, it is because of a cooling problem. Many issues could lead
to this- blocked air filters, dirty air passages etc. Regular checks of the chiller logs should
unearth any anomaly, specifically the comparison between amperage and voltage.

 LIQUID LINE RESTRICTION

If you are a refrigeration technician and you encounter low evaporator pressure, one of the
areas to check is the liquid line, specifically for any form of restriction.

Many other symptoms could point to the problem that affects the system enthalpy as shown by
the following examples:

AR8622 |BUILDING SERVICE III |2017 REGULATION|A.SIVARAMAN M.ARCH|PRIME CAP-KILVELUR 13

 1. Abnormally high discharge temperature
2. Low current draw
3. High superheats
4. Low condensing pressures
5. Local frost close to the restriction
6. Bubbles in sight glass

In commercial cooling, liquid line restriction can degrade cooling capacity of the system by as
much as 50%.

Diagnosis of this problem does not to be fancy, as an experienced technician can tell
something is not okay by just checking the system history or checking visually. If you are
not acquainted with the system, you may need to conduct a few tests to pinpoint the
issue.

The first one is temperature drop test, which is done at all points likely to develop
restriction. You could also perform a freeze test if finding the exact point becomes
troublesome. This test comes in handy when you suspect several components such as
evaporator, feeder tubes and metering device.

Thermal imaging has to be the most advanced and reliable method of identifying liquid line
restriction. It gives real time results that help you identify the problem as shown by
temperature changes.

BASIC COMPONENT OF REFRIGERATION CYCLE :

01. REFRIGERANT,

What is a Refrigerant?

“Refrigerant is the fluid used for heat transfer in a refrigerating system that absorbs heat
during evaporation from the region of low temperature and pressure, and releases heat
during condensation at a region of higher temperature and pressure.”

Classification Refrigerants

I. Primary refrigerants:

 These are the refrigerants which cool the substance or space directly by absorbing
latent heat.

AR8622 |BUILDING SERVICE III |2017 REGULATION|A.SIVARAMAN M.ARCH|PRIME CAP-KILVELUR 14

  It absorbs heat during evaporation in the evaporator and releases heat energy during
condensation in condenser.
 It is also known as direct expansion system
 EXAMPLE: Ammonia, Freon, SO2, Co2 etc.
 These fluids provide refrigeration by undergoing a phase change process in the
evaporator.

II. Secondary refrigerants

 In refrigeration plant a secondary coolant is used as cooling medium which absorb heat
from refrigerated space and transfer to primary refrigerant in evaporator.
 Secondary refrigerants are also known under the name brines or antifreezes

02. COMPRESSOR:

WHAT IS COMPRESSOR?

Compressors are a mechanical device that compresses gases. It is widely used in industries and
has various applications

How They Are Different From Pumps?

 Major difference is that a compressor handles the gases and pumps handles the liquids.
 As gases are compressible, the compressor also reduces the volume of gas.
 Liquids are relatively incompressible.

WHY WE NEED?

Compressors have many everyday uses, such as in :

 Air conditioners, (car, home)

 Home and industrial refrigeration
 Hydraulic compressors for industrial machines
 Air compressors for industrial manufacturing

What are its various types?

Compressor classification can be described by following flow chart:

AR8622 |BUILDING SERVICE III |2017 REGULATION|A.SIVARAMAN M.ARCH|PRIME CAP-KILVELUR 15

 FIG: Classification of Compressor
SOURCE: http://home.iitk.ac.in/~aashishg/compressor%20final.pptx

A. What are dynamic compressors?

 The dynamic compressor is continuous flow compressor is characterized by rotating
impeller to add velocity and thus pressure to fluid.
 It is widely used in chemical and petroleum refinery industry for specific services.
 There are two types of dynamic compressors

(i).Centrifugal Compressor (ii). Axial Flow Compressor

 Achieves compression by applying inertial  The gas is compressed by the rotating action of
forces to the gas by means of rotating a roller inside a cylinder.
impellers.  The roller rotates off-centre around a shaft so
 It is multiple stage ; each stage consists of that part of the roller is always in contact with
an impeller as the rotating element and the cylinder.
the stationary element, i.e. diffuser  Volume of the gas occupies is reduced and the
 Fluid flow enters the impeller axially and refrigerant is compressed.
discharged radially  High efficient as sucking and compressing
 The gas next flows through a circular refrigerant occur simultaneously.
chamber (diffuser), where it loses velocity
and increases pressure.
AR8622 |BUILDING SERVICE III |2017 REGULATION|A.SIVARAMAN M.ARCH|PRIME CAP-KILVELUR 16
B. What are Positive Displacement compressors?

(I).What is Rotary compressors?

 It is a positive-displacement compressor
that uses pistons driven by a crankshaft to
deliver gases at high pressure.
 The intake gas enters the suction manifold,
then flows into the compression cylinder
 It gets compressed by a piston driven in a
reciprocating motion via a crankshaft,
 Discharged at higher pressure

(II).What is Reciprocating compressor?  Working fluid principally flows parallel to the

axis of rotation.
 The energy level of air or gas flowing through
it is increased by the action of the rotor blades
which exert a torque on the fluid
 Have the benefits of high efficiency and
large mass flow rate
 Require several rows of airfoils to achieve
large pressure rises making them complex and
expensive

03. CONDENSER:

WHAT IS CONDENSER?

 A Condenser is a device or unit used to condense a substance from its gaseous to its liquid
state, by cooling it. In so doing, the latent heat is given up by the substance, and will
transfer to the condenser coolant.
 It is used in systems involving heat transfer
 Condensers are typically heat exchangers, which have various designs and come in many
sizes ranging from rather small (hand-held) to very large industrial-scale units used in plant
processes.

AR8622 |BUILDING SERVICE III |2017 REGULATION|A.SIVARAMAN M.ARCH|PRIME CAP-KILVELUR 17

Refrigerant Condenser

 A refrigerator uses a condenser to get rid of heat extracted from the interior of the unit to
the outside air. Condensers are used in air conditioning, industrial chemical processes such
as distillation, steam power plants and other heat-exchange systems.
 Use of cooling water or surrounding air as the coolant is common in many condensers.

Types of Condenser

There are three other condensers used in HVAC systems

1. Water-cooled condensers
2. Air-cooled condensers
3. Evaporative condensers

1. Water Cooled Condenser

 Water cooled condenser uses water as a cooling medium it may be re-circulated or fresh
water depends upon availability
 Although a little more pricey to install, these condensers are the more efficient type, these
condensers require regular service and maintenance.
 They also require a cooling tower to conserve water. To prevent corrosion and the forming
of algae, water cooled condensers require a constant supply of makeup water along with
water treatment.
 The selection of water cooled condenser depends upon cooling load in evaporator
condenser temperature ,availability of water and water inlet and outlet temperature

Types of water cool condenser:

There are mainly three types of condenser

i. Shell & tube type condenser

ii. Shell & coil type condenser
iii. Tube & tube type condenser

i. Shell and tube type condenser:

Compressor discharge gas flows through the tubes in the condenser

 Water is piped into the shell

 The shell acts as a receiver
 The ends of the shell are removed for cleaning
 Most expensive type of condenser

AR8622 |BUILDING SERVICE III |2017 REGULATION|A.SIVARAMAN M.ARCH|PRIME CAP-KILVELUR 18

 Fig: Shell and tube type condenser

ii. Shell & coil type condenser

 Coil of tubing enclosed in a welded shell

 Refrigerant flows through the coil
 Water is discharged into the shell
 When refrigerant comes in contact with the cool water, it condenses and
discharged through outlet valve

iii.Tube and tube type condenser

 Heat exchange takes place between the fluids in the inner and outer tubes
 Refrigerant flows in the outer tube
 Water flows in the inner tube
 Refrigerant and wate flow in opposite directions to maximize the heat transfer rate

AR8622 |BUILDING SERVICE III |2017 REGULATION|A.SIVARAMAN M.ARCH|PRIME CAP-KILVELUR 19

2. Air Cooled Condenser

 The Condenser uses air as cooling medium to condense refrigerant is called as Air Cooled
Condenser.
 If the condenser is located on the outside of the unit, the air cooled condenser can provide
the easiest arrangement. These types of condensers Reject heat to the outdoors and are
simple to install.
 Most common uses for this condenser are domestic refrigerators, upright freezers. A great
feature of the air cooled condenser is they are very easy to clean. Since dirt can cause
serious issues with the condensers performance, it is highly recommended that these be
kept clear of dirt.
 Air cooled condenser requires large surface area because of low specific heat of air
 Air cooled condenser is made of steel, copper or aluminum.

TYPES

There are majorly two types of air cooled condenser.

I. Natural Convection Condenser. II. Forced Convection Condenser

AR8622 |BUILDING SERVICE III |2017 REGULATION|A.SIVARAMAN M.ARCH|PRIME CAP-KILVELUR 20

 - Needs large surface area - Need fan or blower to decrees surface
area.
- Consumes larger space - Consumes less space
- Simple in construction - Complex in construction
- Low cost - High cost comparatively

Advantages & Disadvantages:

Advantages of air cooling condenser is given below

 Used in locations where water is difficult to use

 Very simple construction
 Low initial cost and maintenance cost
 Less piping work to do
 Less chances of fouling
 Very easy to clean

Disadvantages of air cooled condenser

 Low heat transfer rate

 Noisy operation while application
 Large surface area is required
 In hot weathered conditions it is less effective
 It is less efficient than water cooled condenser
 Air cooled condenser cannot be used along with refrigerant having higher compression
index

3. EVAPORATIVE

AR8622 |BUILDING SERVICE III |2017 REGULATION|A.SIVARAMAN M.ARCH|PRIME CAP-KILVELUR 21

While these remain the least popular choice, evaporative condensers can be used inside or
outside of a building and under typical conditions, operate at a low condensing temperature.

Typically these are used in large commercial air conditioning units. Although effective, they are
not necessarily the most efficient.

Evaporative Condenser:

 The refrigerant is flow through a pipe

 Through spray of water the refrigerant is condensed
 A latent heat transfer takes place throughout the pipe

Advantages & Disadvantages:

Advantages of Evaporative Condenser are as follows:

 Evaporation is a part of heat transfer process heat absorption capacity of water is hire than
air it needs less coil surface
 No need of cooling tower.

Disadvantages of evaporative condenser are as follows:

 Needs separate system for water spray.

 Needs regular maintenance.
 This type of condenser can be used only for medium sized refrigeration plant.
EVAPORATOR:

An evaporator is a device in a process used to turn the liquid form of a chemical substance such as
water into its gaseous-form/vapor. The liquid is evaporated, or vaporized, into a gas form of the
targeted substance in that process.

AR8622 |BUILDING SERVICE III |2017 REGULATION|A.SIVARAMAN M.ARCH|PRIME CAP-KILVELUR 22

 Source:http://www.ref-wiki.com/content/view/31533/181/

Refrigeration evaporators:

source: https://nzifst.org.nz/resources/unitoperations/unopsassets/fig6-10.gif

Types of evaporator:

 Forced Convection Type : uses a fan or pump to force the liquid being cooled over the
evap.

 Natural Convection Type : has the liquid being cooled flows naturally to the evap. due to
the density differences of the chilled and warm liquid.

Evaporator Construction Types

There are three types of evaporator- construction that are commonly being used today:

AR8622 |BUILDING SERVICE III |2017 REGULATION|A.SIVARAMAN M.ARCH|PRIME CAP-KILVELUR 23

1) Bare-Tube construction have the entire surface in contact with the evaporating refrigerant
inside.

The bare tube evaporators are made up of copper tubing or steel pipes. The copper tubing is used
for small evaporators where the refrigerant other than ammonia is used, while the steel pipes are
used with the large evaporators where ammonia is used as the refrigerant. The bare tube
evaporator comprises of several turns of the tubing, though most commonly flat zigzag and oval
trombone are the most common shapes. The bare tube evaporators are usually used for liquid
chilling. In the blast cooling and the freezing operations the atmospheric air flows over the bare
tube evaporator and the chilled air leaving it used for the cooling purposes. The bare tube
evaporators are used in very few applications, however the bare tube evaporators fitted with the
fins, called as finned evaporators are used very commonly.

2) Plate Surface

In the plate type of evaporators the coil usually made up of copper or aluminum is embedded in
the plate so as so to form a flat looking surface. Externally the plate type of evaporator looks like a
single plate, but inside it there are several turns of the metal tubing through which the refrigerant
flows. The advantage of the plate type of evaporators is that they are more rigid as the external
plate provides lots of safety. The external plate also helps increasing the heat transfer from the
metal tubing to the substance to be chilled. Further, the plate type of evaporators are easy to
clean and can be manufactured cheaply.

The plate type heat exchangers can be easily formed into various shapes as per the requirement.
Thus in the household refrigerators and the deep freezers, where they are used most commonly,
AR8622 |BUILDING SERVICE III |2017 REGULATION|A.SIVARAMAN M.ARCH|PRIME CAP-KILVELUR 24
they can be converted into the box shape to form the closed enclosure, where various food can be
kept in the frozen state. The plates can also be welded together forming the bank of the plate type
of evaporators that can be used the larger evaporators of higher capacities.

Plate types of evaporators provide excellent shelves in the freezers and similar applications. They
can be used as the as the partitions in the freezers, frozen food display cases, ice cream cabinets,
soda fountains and others. Due to various advantages and flexibility offered by the plate type of
evaporators, they are used extensively.

3) Finned construction are bare-tube coils upon which fins(metal plates usually Aluminium) are
being installed. A more detailed discussion on this type of design will be provided here.The fins are
added to the bare-tube to increase the heat transfer capability. They act as heat collector that pick
up heat from the surrounding air and conduct it to the refrigerant inside the tube hence improving
the efficiency in cooling the air of the surrounding. They are best used in the air-cooling space
where the temperature is around 34°F.Having fins mean the surface area for heat transfer has
been extended. This means that the finned coils can have more compact in design compared to
the bare-tube type of similar capacity. In summary, finned coils help to reduce coil cost, size and
weight.

FIG: Finning Evaporator And Its Types

SOURCE: https://www.brighthubengineering.com/hvac/61270-types-of-refrigeration-
evaporators/

Thermal Contact and Fin Spacing

Good thermal contact between the fins and tubes is a must to ensure efficient heat transfer. They
can be soldered together. The other more practical method is to expand the fins by pressure such
that they bite into the tube surface hence a good thermal contact is established. The spacing of
the fin depend on the operating temperature of the coil. Low temperature application uses only 1
fin.
AR8622 |BUILDING SERVICE III |2017 REGULATION|A.SIVARAMAN M.ARCH|PRIME CAP-KILVELUR 25
In air conditioning application, 14-16 fins per inch may be used as long it is designed in such a way
that frost does not accumulates in the coils. Excessive finning may reduce the capacity of the
evap. by restricting the flow of air over the coil hence the design engineers must do a proper
system calculation and simulation at design stage.

4) Shell and Tube types of Evaporators

The shell and tube types of evaporators are used in the large refrigeration and central air
conditioning systems. The evaporators in these systems are commonly known as the chillers. The
chillers comprise of large number of the tubes that are inserted inside the drum or the shell.
Depending on the direction of the flow of the refrigerant in the shell and tube type of chillers, they
are classified into two types: dry expansion type and flooded type of chillers. In dry expansion
chillers the refrigerant flows along the tube side and the fluid to be chilled flows along the shell
side. The flow of the refrigerant to these chillers is controlled by the expansion valve. In case of
the flooded type of evaporators the refrigerant flows along the shell side and fluid to be chilled
flows along the tube. In these chillers the level of the refrigerant is kept constant by the float valve
that acts as the expansion valve also.

Fig : Shell and tube with the refrigerant boiling in the shell(Liquid chilling evaporators)

Fig : Shell and tube with the refrigerant boiling in the tubes(Liquid chilling evaporators)

AR8622 |BUILDING SERVICE III |2017 REGULATION|A.SIVARAMAN M.ARCH|PRIME CAP-KILVELUR 26

 Fig : a plate type evaporator(Liquid chilling evaporators)

Source: http://www.ref-wiki.com/content/view/31533/181/

REFRIGERANT CONTROL DEVICES

 The refrigerant flow control is one of the four major components in a vapor compression
refrigeration system.
 The function of any refrigerant flow control is to adjust the quantity of refrigerant flow
into the evaporator according to the evaporator load; to create a pressure drop from the
high side to the low side of the system in order to permit the refrigerant to vaporize under
the desired low pressure in the evaporator while at the same time condensing at a high
pressure in the condenser.
 There are various types of refrigerant flow control devices, such as
- Manual expansion valve,
- Capillary tube,
- Thermostatic expansion valve,
- Float valve and
- Electronic expansion valve.
 Hand expansion valves are also called throttle valves.
I. MANUAL EXPANSION VALVE  The expansion valve comprises of main body, valve seat, and hand
wheel which is actuated to change the opening area around the
valve seat to adjust the frictional resistance to the refrigerant flow.
 The rate of the refrigerant
AR8622 |BUILDING SERVICE III |2017 REGULATION|A.SIVARAMAN M.ARCH|PRIME
flow throughCAP-KILVELUR
the valve depends on27 the
pressure differential across the valve and opening of the valve.
 Assuming that the pressure drop across the valve remains the
same, the flow rate through a hand expansion valve will remain
Fig.1: Hand expansion valve

II. CAPILLARY TUBE

 Capillary tubes are widely used as expansion devices in small vapor compression
refrigeration Systems, such as household refrigerators, room air conditioners, and small
package air conditioning units.
 In this system, the capillary tube is wound into with coils for direct expansion.
 The tube connects the outlet of condenser to the inlet of the evaporator
 Physically the capillary tubes are hollow tubes made with drawn copper, with internal
diameters ranging between 0.51and 2 mm
 Primarily there are two kinds of capillary tubes, namely adiabatic and non adiabatic tubes.
 The adiabatic capillary tube expands refrigerant from high pressure to low pressure
adiabatically while in the non-adiabatic situation, the capillary tube forms a counter-flow
heat exchanger with the suction line that joins the evaporator and the compressor .
 The refrigerant flow inside the capillary tube is very complex, particularly in non-adiabatic
situations where the capillary tubes are in thermal contact with the suction lines.
 When the pressure of the sub-cooled liquid refrigerant flowing through the non-adiabatic
capillary tubes drops below the saturation value (corresponding to its temperature), a part
of the refrigerant flashes into vapor.
 This results in two-phase flow while the refrigerant pressure continues to drop due to the
friction and fluid expansion in the capillary tube.
AR8622 |BUILDING SERVICE III |2017 REGULATION|A.SIVARAMAN M.ARCH|PRIME CAP-KILVELUR 28
III. Thermostatic expansion Valves-Superheat Control
 At present, thermostatic expansion valve is probably the most widely used refrigerant flow
control device because of its high efficiency and its ready adaptability to any type of
refrigeration applications.
 The thermostatic expansion valve controls the mass flow rate of the refrigerant into the
evaporator according to inspiration vapor degree of superheat, and at the same time
throttles the liquid from condensing pressure to evaporation pressure.

Fig: The principle of internal equalizer thermostatic expansion valve

 It is an operation diagram of the internal equalizer thermostatic expansion valve, the main
parts including: a needle and seat, a pressure bellow or diaphragm, a fluid-charged remote
bulb, and a spring, the tension of which is usually adjustable by an adjusting screw.
 A screen or strainer is usually installed at the liquid inlet for the valve to prevent the
entrance of foreign material which may cause malfunction of the valve.
 The main important part of the thermostatic expansion valve is the remote bulb, which
responses the superheat of the refrigeration at the outlet of the evaporator and then move
to close or open the valve to throttle the flow of the liquid to the evaporator.
 In order to ensure against refrigerant liquid entering the compressor, it is common practice
to have the refrigerant leave the evaporator slightly superheated.
 Superheat is the difference between the temperature at the bulb and the evaporating
temperature, the former is measured at the point where the remote bulb is located at the
exit of the evaporator coil

IV. Float valve

 A float valve, either high-side or low-side, can serve as a metering device. The high-side
float, located in the liquid line, allows the liquid to flow into the low side when a sufficient
amount of refrigerant has been condensed to move the float ball. No liquid remains in the
receiver. A charge of refrigerant just sufficient to fill the coils is put into the system on
AR8622 |BUILDING SERVICE III |2017 REGULATION|A.SIVARAMAN M.ARCH|PRIME CAP-KILVELUR 29
 installation. This type of float, formerly used extensively, is now limited to use in certain
types of industrial and commercial systems.

 The low-side float valve keeps the liquid level constant in the evaporator. It is used in
flooded-type evaporators where the medium being cooled flows through tubes in a bath of
refrigerant. The low-side float is more critical in operation than the high-side float and
must be manufactured more precisely. A malfunction will cause the evaporator to fill
during shutdown. This condition will result in serious pounding and probable compressor
trouble on start-up.

 Needle valves, either diaphragm or packed type, may be used as hand expansion valves. As
such, they are usually installed in a bypass line around an automatic- or thermostatic-
expansion valve. They are placed in operation when the normal control is out of order or is
removed for repairs.
V. Electronic expansion valve

Fig:1. fig:2.

Fig: 1.A cutaway of an electronic expansion valve (EEV) with step motor and drive assembly. Fig: 2.
The feedback loop.

Source: https://www.achrnews.com/articles/95056-electronic-expansion-valves-the-basics
AR8622 |BUILDING SERVICE III |2017 REGULATION|A.SIVARAMAN M.ARCH|PRIME CAP-KILVELUR 30
The electronic expansion valve (EEV) operates with a much more sophisticated design. EEVs
control the flow of refrigerant entering a direct expansion evaporator. They do this in response to
signals sent to them by an electronic controller. A small motor is used to open and close the valve
port.

The motor is called a step or stepper motor. Step motors do not rotate continuously. They are
controlled by an electronic controller and rotate a fraction of a revolution for each signal sent to
them by the electronic controller. The step motor is driven by a gear train, which positions a pin in
a port in which refrigerant flows. A cutaway of an EEV with step motor and drive assembly is
shown in above mentioned Figure .

AR8622 |BUILDING SERVICE III |2017 REGULATION|A.SIVARAMAN M.ARCH|PRIME CAP-KILVELUR 31

ELECTRIC MOTORS:

Electric Motors Basics - The HVAC industry depends heavily on the electric motor. Furthermore,
the electric motor is the primary component that powers blowers to move air. Additionally,
electric motors drive compressors to compress refrigerant. Lastly, the electric motor powers a
pump to move water for chilled water and hot water applications and fuel oil.

Additionally, the electric motor is an integral part of all HVAC systems, and many HVAC
applications would be impossible to implement without the old electric motor.

Electric Motors Basics | HVAC Technical

Flex is Crimped & Flex was Hitting Belt - System Repaired After Photo was Taken

 HVAC equipment depends on electric motors to move air, pump water, and run
compressors. Therefore, technicians need to understand electric motor basics.
 Depending on the application will depend on the type of motor required for the job.
 Additionally, the design engineer must select the appropriate HVAC motor for the job;
otherwise, significant and continuous problems will occur throughout the life of the HVAC
system.
 Electric blower motors or propeller fans usually require electric motors with a low starting
torque, while compressors require motors with a high starting torque.
 Finally, these characteristics are essential, especially when selecting the appropriate
electric motor for the application.
Hermetic Compressors with Integral Motors
A compressor electric motor with a low starting torque rating is doomed to failure while a blower
motor or propeller blade electric motor with an unnecessarily high torque rating will end up
costing more in energy costs over the life of the equipment and electric motor.
Electric Motors Basics - Single Phase Motors
AR8622 |BUILDING SERVICE III |2017 REGULATION|A.SIVARAMAN M.ARCH|PRIME CAP-KILVELUR 32
Split-phase motors are the workhorse of the HVAC industry. Additionally, a split-phase electric
motor has two windings – a start and run winding. There two common split-phase motors used in
HVAC applications. Furthermore, one of the split-phased electric motors used in HVAC
applications is the capacitor-start-induction-run motor, and it is also a single-phase electric motor.

The capacitor start motor uses a start capacitor to boost its starting torque. Additionally, most
capacitor start motors use a centrifugal switch to disengage the start capacitor from the start
winding circuit when the motor reaches approximately 70 to 80 percent of its run speed.

The other common split-phase electric motor used for HVAC applications is the resistance-start-
induction-run electric motor. This electric motor has a start winding and a run winding, and single-
phase current applied to both windings on start-up. Additionally, the two windings are out of
phase by 45 to 90 degrees, which gives the motor a boost on start-up. Next, this resistance-start-
induction-run motor does not utilize a capacitor as the capacitor=start-induction-run electric
motor does. Furthermore, the resistance-start-induction-run electric motor does use a centrifugal
switch to drop the start winding out of the circuit just as the capacitor-start-induction-run motor
does.

Electric Motors Basics - PSC Motors

Another common electric motor used in many HVAC applications is the permanent split capacitor
(PSC) electric motor. Unlike the three-phase electric motor, the PSC electric motor is a single-
phase electric motor. These electric motors are usually easily reversible from the clockwise
direction to the counter-clockwise direction. Furthermore, the PSC electric motor uses a capacitor
and has a good running efficiency. Furthermore, it only has a moderate torque rating on startup.
However, it is used for many refrigeration and air conditioning compressor applications.
Usually, when a PSC electric motor drives a compressor and has two capacitors attached to its
wiring. A start capacitor to boost the starting torque and a run capacitor to increase its running
efficiency. Furthermore, the start capacitor is usually only in the circuit for a second at startup. It
then drops out of the compressor circuit by a special relay. The start capacitor must drop out of
the circuit quickly after startup. Finally, if the relay fails in a closed position and the start capacitor
remains in the circuit, the start winding in the PSC electric motor can burn up, rendering the
compressor useless.

The shaded-pole electric motor is used in HVAC applications. Typically for only fractional
horsepower applications where the start and run torque requirements are very minimal. Finally,
the shaded-pole electric motor does not use a capacitor and not easily reversible.

AR8622 |BUILDING SERVICE III |2017 REGULATION|A.SIVARAMAN M.ARCH|PRIME CAP-KILVELUR 33

AIR HANDLING UNITS:

An air handler, or air handling unit (often abbreviated to AHU), is a device used to condition and
circulate air as part of a heating, ventilating, and air-conditioning (HVAC) system.

AR8622 |BUILDING SERVICE III |2017 REGULATION|A.SIVARAMAN M.ARCH|PRIME CAP-KILVELUR 34

An air handler is usually a large metal box containing a blower, heating or cooling elements, filter
racks or chambers, sound attenuators, and dampers. Air handlers usually connect to ductwork
that distributes the conditioned air through the building and returns it to the AHU.

Sometimes AHUs discharge (supply) and admit (return) air directly to and from the space served
without ductwork.

Small air handlers, for local use, are called terminal units, and may only include an air filter, coil,
and blower; these simple terminal units are called blower coils or fan coil units. These units are
used for air-conditioning small spaces like guest rooms in hotels, hospital patient rooms, etc.

• A larger air handler that conditions 100% outside air, and no recirculated air, is
known as a makeup air unit (MAU).
• An air handler designed for outdoor use, typically on roofs, is known as a packaged
unit (PU) or rooftop unit (RTU).

An air handling unit; air flow is from the right to left in this case. Some AHU components shown
are:

1 - Supply duct 2 - Fan compartment 3 - Vibration isolator ('flex joint')

4 - Heating and/or cooling coil 5 - Filter compartment 6 - Mixed (recirculated + outside)
air duct

AR8622 |BUILDING SERVICE III |2017 REGULATION|A.SIVARAMAN M.ARCH|PRIME CAP-KILVELUR 35

 A rooftop packaged unit or RTU

Fan Coil Unit:

 When it becomes necessary to condition a large number of small individually controlled

rooms such as in motels, hotels, apartment houses, medical centres and hospitals, it is
economical to circulate hot and chilled water to small fan coils located in each room.
 A fan coil unit is a small air handling unit, which is usually installed in the ceiling space
above an entrance hall, closet or bathroom.
 Ordinarily, hot and chilled water are piped to the unit, although electric strip heaters may
replace the hot water coil.
 A thermostat actuates the hot water or chilled water valve, and a fan switch controls the
amount of air delivered to the room for quick heating or cooling.

How AHU works?

Fig : working section of AHU

Source:https://palashdas.files.wordpress.com/2013/11/0474e-hepaschem2.jpg?w=640&h=284
AR8622 |BUILDING SERVICE III |2017 REGULATION|A.SIVARAMAN M.ARCH|PRIME CAP-KILVELUR 36
Operation

• The basic function of the AHU is to suck air from the rooms, let it pass through chilled
water cooling coils and then discharging the cooled air back to the rooms.
• Normally, letting it pass through panel or bag filters also filters the air.
• A certain amount of fresh air may be introduced at the suction duct so that air in the
rooms may be gradually replaced.
• AHU's come in many sizes and shapes.
• Usually, the air conditioning designer will choose a particular AHU based on the air flow
requirements and the cooling capacity.
• If humidity of the air has to be controlled, steam coils, or other heating coils may be
installed.
• If the air has to be very cleaned, special filters have to be installed at the ducting outlets or
at the AHU filter box.
• Moisture in the air is condensed out when it comes into contact with the chilled water
coils.
• At the bottom of the AHU, a pipe is installed so that water that is collected can be drained
out.
• Air handling units often use a squirrel cage blower powered by the AC electric motor to
circulate air. The air flow rate is controlled by vanes or dampers on the fan. Small air
handling units also contain a fuel-burning heater or heat pump which is placed in the air
stream to heat it. Larger air handling units use coils to circulate hot steam or water for
heating, and circulate chilled water for cooling purposes.
• The fan and motor assembly is usually mounted on vibration dampers that absorb any
vibrations generated. Removable panels are installed so that personnel can enter into the
AHU for maintenance. Maintenance is mostly changing or washing of air filters, greasing of
bearings, changing of belts, and general inspection and cleaning work.
•
DETAILED AIR HANDLING UNIT:

AR8622 |BUILDING SERVICE III |2017 REGULATION|A.SIVARAMAN M.ARCH|PRIME CAP-KILVELUR 37

Types of AIR HANDLING UNIT:

• Small air handling units, called terminal units, often contain only a blower, air filter
and heater, and are used for local use.
• Larger air handling units that condition outside air are called makeup air units
• A packaged unit refers to an air handling unit exclusively designed for outside use,
and is typically found on roofs.

Roof top air-condition: The air handling units are installed at the different places in the building to
be air conditioned. They are connected to the cool air supply and return air ducts which are laid in
all the rooms to be cooled. In case of the central air conditioning plants the air handling units are
installed on the floor,
while in case of the split air conditioners, they are mounted on the roof inside the room above the
false ceiling.
In case of packaged units they can be installed on the floor or the roof.

AIR HANDLER COMPONENTS

1. Blower/fan 2. Heating and/or cooling elements 3. Filters
4. Humidifier 5. Mixing chamber 6. Heat recovery
device
7. Controls 8. Vibration isolators
1.BLOWER/FAN:

 Air handlers typically employ a large squirrel cage blower driven by an AC induction electric
motor to move the air.
 The blower may operate at a single speed, offer a variety of set speeds, or be driven by a
Variable Frequency Drive to allow a wide range of air flow rates.
 Flow rate may also be controlled by inlet vanes or outlet dampers on the fan.
AR8622 |BUILDING SERVICE III |2017 REGULATION|A.SIVARAMAN M.ARCH|PRIME CAP-KILVELUR 38
  Some residential air handlers (central 'furnaces' or 'air conditioners') use a brushless DC
electric motor that has variable speed capabilities.
 Multiple blowers may be present in large commercial air handling units, typically placed at
the end of the AHU and the beginning of the supply ductwork (therefore also called
"supply fans").
 They are often augmented by fans in the return air duct ("return fans") pushing the air into
the AHU.

2.HEATING AND/OR COOLING ELEMENTS

 Air handlers may need to provide heating, cooling, or both to change the supply air
temperature depending on the location and the application.
 Smaller air handlers may contain a fuel-burning heater or a refrigeration evaporator,
placed directly in the air stream. Electric resistance and heat pumps can be used as well.
Evaporative cooling is possible in dry climates.
 Large commercial air handling units contain coils that circulate hot water or steam for
heating, and chilled water for cooling.
 Coils are typically manufactured from copper for the tubes, with copper or aluminium fins
to aid heat transfer.
 Cooling coils will also employ eliminator plates to remove and drain condensate.
 The hot water or steam is provided by a central boiler, and the chilled water is provided by
a central chiller.
 Downstream temperature sensors are typically used to monitor and control 'off coil'
temperatures, in conjunction with an appropriate motorized control valve prior to the coil.

3.FILTERS

 Air filtration is almost always present in order to provide clean dust-free air to the building
occupants.
 It is typically placed first in the AHU in order to keep all its components clean. Depending
upon the grade of filtration required, typically filters will be arranged in two (or more)
banks with a coarse-grade panel filter provided in front of a fine-grade bag filter, or other
'final' filtration medium.
 The panel filter is cheaper to replace and maintain, and thus protects the more expensive
bag filters.

AR8622 |BUILDING SERVICE III |2017 REGULATION|A.SIVARAMAN M.ARCH|PRIME CAP-KILVELUR 39

4.HUMIDIFIER

Humidification is often necessary in colder climates where continuous heating will make the air
drier, resulting in uncomfortable air quality and increased static electricity.

Various types of humidification may be used:

1.Evaporative 2.Vaporizer 3.Spray mist

4.Ultrasonic 5.Wetted medium

5.MIXING CHAMBER

In order to maintain indoor air quality, air handlers commonly have provisions to allow the
introduction of outside air into, and the exhausting of air from the building.

In temperate climates, mixing the right amount of cooler outside air with warmer return air can be
used to approach the desired supply air temperature.

A mixing chamber is therefore used which has dampers controlling the ratio between the return,
outside, and exhaust air.

6.HEAT RECOVERY DEVICE

A heat recovery device heat exchanger of many types, may be fitted to the air handler between
supply and extract airstreams for energy savings and increasing capacity. These types more
commonly include for:

• Recuperator, or Plate Heat exchanger:

• Thermal Wheel, or Rotary heat exchanger:
• Run around coil
• Heat Pipe
7.CONTROLS
• Controls are necessary to regulate every aspect of an air handler, such as: flow rate of air,
supply air temperature, mixed air temperature, humidity, air quality.
• They may be as simple as an off/on thermostat or as complex as a building automation
system using BACnet or LonWorks, for example.
• Common control components include temperature sensors, humidity sensors, sail
switches, actuators, motors, and controllers.
8. VIBRATION ISOLATORS
• The blowers in an air handler can create substantial vibration and the large area of the
duct system would transmit this noise and vibration to the occupants of the building.
• To avoid this, vibration isolators (flexible sections) are normally inserted into the duct
AR8622 |BUILDING SERVICE III |2017 REGULATION|A.SIVARAMAN M.ARCH|PRIME CAP-KILVELUR 40
 immediately before and after the air handler and often also between the fan compartment
and the rest of the AHU. The rubberized canvas-like material of these sections allow the air
handler to vibrate without transmitting much vibration to the attached ducts.
• The fan compartment can be further isolated by placing it on a spring suspension, which
will mitigate the transfer of vibration through the floor.

COOLING TOWERS:
A cooling tower is a heat rejection device that rejects waste heat to the atmosphere through the
cooling of a water stream to a lower temperature. Cooling towers may either use
the evaporation of water to remove process heat and cool the working fluid to near the wet-bulb
air temperature or, in the case of closed circuit dry cooling towers, rely solely on air to cool the
working fluid to near the dry-bulb air temperature.
Common applications include cooling the circulating water used in oil
refineries, petrochemical and other chemical plants, thermal power stations, nuclear power
stations and HVAC systems for cooling buildings.

Fig: Section of Cooling Tower

GENERAL CLASSIFICATION BASED ON AIR FLOW
The classification is based on the type of air induction into the tower: the main types of
cooling towers are
1. Natural draft cooling tower
Utilizes buoyancy via a tall chimney. Warm, moist air naturally rises due to the density
differential compared to the dry, cooler outside air. Warm moist air is less dense than drier
air at the same pressure. This moist air buoyancy produces an upwards current of air
through the tower.

AR8622 |BUILDING SERVICE III |2017 REGULATION|A.SIVARAMAN M.ARCH|PRIME CAP-KILVELUR 41

 Fig: Concept of Natural Draft Cooling Tower
Source: https://www.researchgate.net/figure/Natural-draft-cooling-tower-wet-
type_fig3_327830964
2. Mechanical draft cooling towers
Uses power-driven fan motors to force or draw air through the tower.

Induced draft — A mechanical draft tower with a fan at the discharge (at the top)
which pulls air up through the tower. The fan induces hot moist air out the discharge.
This produces low entering and high exiting air velocities, reducing the possibility
of recirculation in which discharged air flows back into the air intake. This fan/fin
arrangement is also known as draw-through.

Fig: A mechanical draft tower with a fan at the discharge (at the top) which pulls air

Source: https://www.tradeindia.com/fp4466108/Mechanical-Type-Induced-Draft-
Cross-Flow-Cooling-Towers.html

Forced draft — A mechanical draft tower with a blower type fan at the intake. The
fan forces air into the tower, creating high entering and low exiting air velocities. The
AR8622 |BUILDING SERVICE III |2017 REGULATION|A.SIVARAMAN M.ARCH|PRIME CAP-KILVELUR 42
 low exiting velocity is much more susceptible to recirculation. With the fan on the air
intake, the fan is more susceptible to complications due to freezing conditions. Another
disadvantage is that a forced draft design typically requires more motor horsepower
than an equivalent induced draft design. The benefit of the forced draft design is its
ability to work with high static pressure. Such setups can be installed in more-confined
spaces and even in some indoor situations. This fan/fin geometry is also known
as blow-through.

Fig: section of forced draft cooling tower

Source: https://www.exportersindia.com/baffles-systems/forced-draft-cooling-tower-coimbatore-
india-929763.htm

3. Fan assisted natural draft — A hybrid type that appears like a natural draft setup, though
airflow is assisted by a fan.
Hyperboloid (sometimes incorrectly known as hyperbolic) cooling towers have become
the design standard for all natural-draft cooling towers because of their structural
strength and minimum usage of material. The hyperboloid shape also aids in
accelerating the upward convective air flow, improving cooling efficiency. These
designs are popularly associated with nuclear power plants. However, this association is
misleading, as the same kind of cooling towers are often used at large coal-fired power
plants as well. Conversely, not all nuclear power plants have cooling towers, and some
instead cool their heat exchangers with lake, river or ocean water.
Thermal efficiencies up to 92% have been observed in hybrid cooling towers

AR8622 |BUILDING SERVICE III |2017 REGULATION|A.SIVARAMAN M.ARCH|PRIME CAP-KILVELUR 43

 Fig : Section of Fan assisted natural draft
Source: https://www.europages.co.uk/Natural-draft-cooling-towers/HAMON/cpid-
5561190.html
CLASSIFICATION BASED ON HEAT TRANSFER METHODS
With respect to the heat transfer mechanism employed, the main types are:

 Wet cooling towers (or open circuit cooling towers) operate on the principle of evaporative
cooling. The working fluid and the evaporated fluid (usually water) are one and the same.
 Closed circuit cooling towers (or fluid coolers) pass the working fluid through a tube bundle,
upon which clean water is sprayed and a fan-induced draft applied. The resulting heat transfer
performance is close to that of a wet cooling tower, with the advantage of protecting the
working fluid from environmental exposure and contamination.
 Dry cooling towers are closed circuit cooling towers which operate by heat transfer through a
surface that separates the working fluid from ambient air, such as in a tube to air heat
exchanger, utilizing convective heat transfer. They do not use evaporation.
 Hybrid cooling towers are closed circuit cooling towers that can switch between wet and dry
operation. This helps balance water and energy savings across a variety of weather conditions.

AR8622 |BUILDING SERVICE III |2017 REGULATION|A.SIVARAMAN M.ARCH|PRIME CAP-KILVELUR 44

District Cooling System (DCS)

What is District Cooling?

Basically, a district cooling system (DCS) distributes cooling capacity in the form of chilled water or
other medium from a central source to multiple buildings through a network of underground
pipes for use in space and process cooling. Individual user purchases chilled water for their
building from the district cooling system operator and do not need to install their own chiller
plants. For this system, a central chiller plant, a pump house and a distribution pipeline network
are required.

The DCS is an energy-efficient air-conditioning system as it consumes 35% and 20% less electricity
as compared with traditional air-cooled air-conditioning systems and individual water-cooled air-
conditioning systems using cooling towers respectively. In some countries that have substantial
heating demand, the plant can also be designed to supply hot water to form a District Heating and
Cooling System (DHCS).

A typical DCS comprises the following components:

 Central Chiller Plant - generate chilled water for cooling purposes.

 Distribution Network - distribute chilled water to buildings
 User Station - interface with buildings' own air-conditioning circuits.

Central Chiller Plant

Chilled water is typically generated at the central chiller plant by compressor driven chillers,
absorption chillers or other sources like ambient cooling or “free cooling” from deep lakes, rivers,
aquifers or oceans.

Groups of large and energy-efficient water-cooled chillers are usually installed in a central chiller
plant to take advantage of the economy of scale and the cooling demand diversity between
different buildings within a district. Sea water condensers or fresh water cooling towers can be
utilized to reject waste heat from the central chillers.

AR8622 |BUILDING SERVICE III |2017 REGULATION|A.SIVARAMAN M.ARCH|PRIME CAP-KILVELUR 45

 Concept of District Cooling

AR8622 |BUILDING SERVICE III |2017 REGULATION|A.SIVARAMAN M.ARCH|PRIME CAP-KILVELUR 46

AR8622 |BUILDING SERVICE III |2017 REGULATION|A.SIVARAMAN M.ARCH|PRIME CAP-KILVELUR 47
Distribution Network
District chilled water is distributed from the cooling source(s) to the user stations through supply
pipes and is returned after extracting heat from the building’s secondary chilled water systems.
Pumps distribute the chilled water by creating a pressure differential between the supply and
return lines.

User Station
The interface between the district cooling system and the building cooling system is commonly
referred to as user station. The user station would usually comprise of air handling units, heat
exchanger and chilled water piping in the building.

A user station is required in each user's building to connect the DCS distributed chilled water pipe
to the building. Inside the user station, devices called heat exchangers are installed to transfer
heat between the chilled water supply of DCS and the air-conditioning system of the user building.
The user station could be designed for direct or indirect connection to the district cooling
distribution system.

With direct connection, the district cooling water is distributed within the building directly to
terminal equipment such as air handling and fan coil units, induction units, etc. An indirect
connection utilizes one or multiple heat exchangers in between the district system and the
building system.

AR8622 |BUILDING SERVICE III |2017 REGULATION|A.SIVARAMAN M.ARCH|PRIME CAP-KILVELUR 48

AR8622 |BUILDING SERVICE III |2017 REGULATION|A.SIVARAMAN M.ARCH|PRIME CAP-KILVELUR 49
AIR-CONDITION: ENERGY EFFICIENT SYSTEMS,
Energy efficient air conditioners are continuously being developed as the demand for them
continued to increase as the fight to reduce global warming accelerates. Reduction in the power
used by air conditioners will translate to a reduction in carbon footprint as most of our power
utilities still use fossil fuel to generate the electricity.

The days of using ozone-friendly refrigerants since Montreal Protocol are already here and as a
result, this hole above the Antarctica has been shown to be shrinking.

Ozone-unfriendly refrigerant such as R22 is no longer in production and although you can still
purchase equipment with this gas through recycling process, it will eventually be replaced by
other ozone-friendly refrigerants such as R407C, R410A and R32. These refrigerants have zero
ozone depletion potential.

Choosing Energy Efficient Air Conditioners

In general, the more efficient the equipment is, the more costly it is compared to the regular ones.
Here are some steps that you can take when choosing energy efficient air conditioners to
purchase.

1. Cooling Capacity

Determine the cooling capacity that is required of the room. A rough estimates of how to
do this is provided here. Buying an oversize air conditioner is not a good choice as it is
more costly and does not necessarily provide better comfort level.

Air Conditioning Calculations

How do you do air conditioning calculations on the capacity of air conditioner for
your room? This calculation is important because if done wrongly, you will end up installing
an oversize or undersize equipment. An oversized air conditioner is not good as the
compressor will run and stop regularly and not able to cool the room uniformly.

It will also cause discomfort to the occupants as the dehumidfication of the room is not
properly done. On top of that, the electricity bill will be high as the compressor turns on
and off too often.

Every time the on/off type of compressor starts to run, its power consumption is 6 times
higher than when it is running steadily.

AR8622 |BUILDING SERVICE III |2017 REGULATION|A.SIVARAMAN M.ARCH|PRIME CAP-KILVELUR 50

 The cycling on and off of the compressor will lead to shorter life span of the compressor
besides having to spend more on the unit price and installation cost.

An undersized unit will not be able to cool the room properly and more so if the weather is
hot.

Cooling Capacity

Cooling capacity for a room is defined as the heat load in a room that have to be removed
in order to achieve a certain room temperature and humidity. The typical design is set to
24°C temperature and 55% Relative Humidity.

Study shows that this combination of temperature and RH is the most conducive for the
human body. The unit used to measure heat load is BTU/hr. 1 BTU/hr is the heat energy
needed to increase 1 pound of water by 1°F.

When choosing an air conditioner, usually a 1 HP (horse power) equipment is able to

remove 9,000 BTU/hr of heat. With better technology, some machines are able to remove
10,000 BTU/hr of heat with the same capacity. The higher the listed BTU/hr, the greater
the cooling capacity.

Air Conditioning Calculations - Rule Of Thumb

Calculating the cooling capacity needed for your room is a complicated process as there
are many factors to consider. However, there is a simple rule of thumb that you can use to
estimate the required cooling capacity for your room. Use this result to compare with the
calculation done by the air conditioning contractors for your own checking purposes.

Step 1
Find the volume of your room in cubic feet. This is done by measuring the length, width
and height of the room in feet and multiply all the three dimensions together.
Volume = Width X Length X Height (cubic feet)
Step 2
Multiply this volume by 6.
C1 = Volume X 6
Step 3
Estimate the number of people (N) that will usually occupy this room. Each person
produces about 500 BTU/hr of heat for normal office-related activity. Multiply this two
figures together.
C2 = N x 500 BTU/hr
Step 4
AR8622 |BUILDING SERVICE III |2017 REGULATION|A.SIVARAMAN M.ARCH|PRIME CAP-KILVELUR 51
 Add C1 and C2 together and you will get a very simplified cooling capacity needed for the
room.
Estimated Cooling Capacity needed = C1 + C2 (BTU/hr)
Air Conditioning Calculations - Other Factors

Other factors that your contractor will consider to determine the sizing of the cooling
capacity include the direction of your room. If the room is facing east or west, additional
capacity is needed as it will be exposed to the morning and evening sun compared to a
room that faces north or south.

If the lighting of the room emits a lot of heat, additional capacity is needed. If electrical
appliances that generate heat is used, additional capacity has to be factored in.

The type of material of the room and windows are also important consideration.

2. INVERTER VS NON-INVERTER

Choose an inverter model as it will be definitely more efficient than a non-inverter unit. The
inverter compressor's rotation can be varied according to the requirements of the load hence the
power savings is there.On the other hand, the non-inverter compressor is only able to turn ON or
OFF. It is not able to vary its speed according to the load. The frequent turning ON and OFF will
consume more energy.

Choose also a DC inverter compressor as it is more efficient compared to the AC inverter.

Diakin, the company which specializes in HVAC industry has developed a reluctance DC motor of
the compressors which have high strength neodymium magnets that are embedded in the
rotating shafts of the compressors' motors. These magnets are 10 times more powerful than the
normal ferrite magnets hence providing a more superior torque for the compressors, making
Daikin the technology leader in this field.

3. COP, EER and SEER

Check the brochures for the efficiency of the model. Every model will have different values and it
also varies with different manufacturers.

COP is the ratio of the cooling capacity(W) vs the power input(W). The higher the value, the more
efficient it is as it is able to provide more cooling for the same power input.

If it is not given, do your own calculation. For ease of cooling capacity conversion, 1W=3.4121
Btu/h. Choose a higher COP model.

AR8622 |BUILDING SERVICE III |2017 REGULATION|A.SIVARAMAN M.ARCH|PRIME CAP-KILVELUR 52

EER is the ratio of the cooling capacity(Btu/h) vs the power input(W). As with COP, choose a
higher EER rating and the unit will consume less energy for the same capacity.

SEER is the ratio of the total cooling that the equipment is able to provide over the entire season
(Btu) Vs the total energy(Watt-hours) consumed. SEER is more accurate as it takes into
consideration the start-up and shut-down cycles of the air conditioner. Choose a higher value for
energy efficient air conditioners.

4. ENERGY STAR RATING

Every country has its own energy ratings for the model of the air conditioner that has been
tested.Choose one that has the highest rating as this would mean that the unit is much more
efficient compared to another lower star rating.

5. INFRA-RED SENSOR

Some manufacturers such as Daikin have built-in infra-red sensor that is able to detect the
presence or absence of the occupants in the room. If it does not detect any movement for a
certain period of time, it will adjust the set temperature higher automatically to reduce the
temperature in the room. This will help to save your electricity bill.

AR8622 |BUILDING SERVICE III |2017 REGULATION|A.SIVARAMAN M.ARCH|PRIME CAP-KILVELUR 53

AIR-CONDITION: ENVIRONMENTAL ASPECTS AND LATEST
INNOVATIONS:
ENVIRONMENTAL CONCERN
In worldwide scenario Fluorocarbon emissions generated during product manufacture and
electricity used during air conditioner use, are the major contributors to global warming.
HOW DOES GLOBAL WARMING OCCUR?
The Earth maintains a balance of heat: in the daytime, heat from the sun warms the planet, while
at night this heat is emitted back out of the Earth’s atmosphere. But if greenhouse gases like CO2
increase, heat is trapped and the Earth’s surface temperature rises. This is the global warming
phenomenon.

 The sun’s heat escapes back into space after warming the earth, thus maintaining an
atmospheric temperature ideal for life.
 The greenhouse effect causes the temperature to rise.
 CO2 and other greenhouse gases.
 Greenhouse gases in the atmosphere increase.

How Does Ozone Layer Depletion Occur?

The stratospheric ozone layer above the Earth’s atmosphere protects us by absorbing the sun’s
harmful ultraviolet (UV) rays. However, a little more than 20 years ago, it was discovered that the
ozone layer above the Antarctic had become thin. Scientists pointed out that this was the result of
the ozone layer being broken down by CFCs (designated fluorocarbons) used as refrigerants in air-
conditioners and refrigerators.

To prevent refrigerants from entering the atmosphere, AC manufacturers takes great care to
ensure that air-conditioners and refrigerators that have reached the end of their useful life are
properly handled by retail outlets.
AR8622 |BUILDING SERVICE III |2017 REGULATION|A.SIVARAMAN M.ARCH|PRIME CAP-KILVELUR 54
 What Should Air-conditioners Do for the Environment?

There are two main ways that air-conditioners impact the environment in a life cycle that
includes manufacture, use by customer, recovery, and disposal at the end of useful
life.

01. Air-conditioners need electricity to operate, and power plants generate CO2
(carbon dioxide) through the process of power generation. This is a cause of global
warming:
02. Air-conditioners use fluorocarbons as refrigerants. Fluorocarbons affect the ozone
layer and contribute to global warming (In addition to the above, there are other
things that must be done: making efficient use of the resources used as raw
materials for air-conditioners; and properly disposing of or recycling used air-
conditioners.)

Few Ways to reduce Environment impact:

 To use reasonable endeavors to reduce the environmental impacts arising out of its operations;
 To use reasonable endeavors to make products energy efficient and reduce pollution;
 To use reasonable endeavors to improve the use of resources and minimize waste through
improved resource efficiency;
 To comply with all relevant environmental legislation and codes of practices;
 To continually improve its performance in the aspect of environmental protection through
trainings conducted to its staff and subcontractors, and thus enhances their awareness and
competence.

AR8622 |BUILDING SERVICE III |2017 REGULATION|A.SIVARAMAN M.ARCH|PRIME CAP-KILVELUR 55

NEW INNOVATIONS IN AIR CONDITIONING
Many people pay attention to the latest in flashy gadgets like smartphones and video game
consoles. But few know what’s going on in the world of heating and cooling. We understand that
this may not be the most interesting subject for today’s homeowner—but maybe it should be.
After all, air conditioning can account for a majority of your utilities in the summertime!

1.HIGH EFFICIENCY EQUIPMENT

Today, air conditioners are more efficient than they’ve ever been before. Variable speed settings
allow an air conditioner to work at a lower speed while keeping more precise temperatures. And
in general, the technology used in manufacturing allows properly-sized air conditioners to cool a
home faster while using less energy. The higher the SEER (Seasonal Energy Efficiency Ratio), the
more you save! Look for a SEER rating of 15 or higher for the most efficient systems.

2.UV LIGHTS

A UV light system is a system that can keep your air a whole lot healthier. Some of the biggest
threats to your air quality are viruses, bacteria, and other germs, tiny microorganisms that can
make you sick when they are airborne. A UV light system can be installed within the ductwork to
kill and sterilize these airborne contaminants so they no longer affect your air quality.

FIG: Air handling unit with UV lamps irradiating both upstream and downstream sides of the
cooling coil.

3.SMART THERMOSTATS

A smart thermostat, or Wi-Fi thermostat, can help you cool your home in a smarter way. You can
set a schedule for home cooling that helps to reduce monthly costs, and it can even automatically
learn and adjust to your daily habits.Most importantly, a smart thermostat can be operated from

AR8622 |BUILDING SERVICE III |2017 REGULATION|A.SIVARAMAN M.ARCH|PRIME CAP-KILVELUR 56

almost anywhere! You can use your smart phone to raise the temperature if the kids’ soccer game
is running late or to cool the home if you’ll be there early. It’s convenience and efficiency in one!

4.DUCTLESS SYSTEMS

Many homes are without functional air ducts. In the past, this has meant that homeowners had to
use window air units and portable air conditioners for cooling. But today, you can go ductless!

A ductless system has indoor air handlers located high up on walls of different rooms throughout
the home. Think of these like the vents of a conventional air conditioner/furnace—except that
they also contain a blower, coil, and some other vital components. Each unit connects to an
outdoor condenser/compressor unit, and are able to cool and heat the room!

5.GEOTHERMAL AIR CONDITIONING AND HEATING

AR8622 |BUILDING SERVICE III |2017 REGULATION|A.SIVARAMAN M.ARCH|PRIME CAP-KILVELUR 57

Geothermal air conditioning and heating uses an underground system (and some familiar above-
ground components) to provide your home with heating and cooling thanks to the heat energy of
the earth. Underground, the temperature remains relatively constant when compared to the
temperature of the air outside of your home. That makes it a reliable source of heat energy for
both heating and the thermodynamic process of cooling.

To heat your home, the underground system circulates water, which moves to a heat pump to
heat the air moving throughout your home. In summer, a heat pump absorbs heat from your
home and deposits it into the earth. This is a smart, long-lasting, and highly efficient way to stay
warm and cool throughout the year!

6.SUSTAINABLE RETROFITS

Fig: HVAC technician installing CATALYST on an older rooftop unit; via Cooper Oates Air
Conditioning

Replacing old HVAC equipment can be expensive and time consuming but leaving clunky (solid,
heavy, and old-fashioned.), outdated technology in place can also be costly and wasteful. That is
why Transformative Wave has developed a new generation of sustainable retrofit technology. The
system, known as CATALYST, installs directly into existing rooftop units, endowing them with the
latest sustainable features — economizers, variable fan speeds, demand-response ventilation,
smart controls and automated capabilities. — leading to a 25% to 50% reduction in energy use.

7.RECYCLABLE DUCTWORK
Not all sustainable solutions involve high-tech gadgets and Wi-Fi connections. GatorDuct is a
simple cardboard product — treated with a fire-resistant and waterproof coating — that takes the
AR8622 |BUILDING SERVICE III |2017 REGULATION|A.SIVARAMAN M.ARCH|PRIME CAP-KILVELUR 58
place of ordinary HVAC ductwork. These triple-walled cardboard ducts are stronger, lighter,
cheaper and require 20% less insulation than their sheet metal counterparts. The kraft paper
surface also allows the ductwork to be custom printed with decorative patterns and company
logos. Best of all, GatorDucts are produced from sustainably managed forests and are 100%
recyclable.

8.DIGITAL CEILINGS
The digital ceiling is the future of building automation. These ceilings are equipped with a variety
of sensors — detecting motion, occupancy levels, temperature, carbon dioxide levels and more —
that converge the building’s lighting, security and HVAC systems into a single, easy to manage
network. These adaptive sensors learn the daily habits of building occupants and automatically
adjust air and light settings accordingly; maximizing comfort while minimizing energy waste.

9.ICE-POWERED AIR CONDITIONING

The Ice Bear is a thermal battery that transforms existing air conditioners into cost-effective
cooling machines. During the night, when the electric grid is less burdened, Ice Bear fills with
water and freezes it into a block of ice. During the day, this ice is used to provide affordable air
conditioning to the building, without running the air conditioner’s energy-guzzling compressor.
This results in 95% less energy use during the hottest hours of the day, drastically cutting both
electricity bills and carbon emissions.

AR8622 |BUILDING SERVICE III |2017 REGULATION|A.SIVARAMAN M.ARCH|PRIME CAP-KILVELUR 59

 Fig:The thermal battery inside an Ice Bear unit; via Ice Energy
10.DeVAP Air Conditioning

Fig: NREL engineers with the DeVAP prototype. Photo by Dennis Schroeder; via NREL

The Desiccant-Enhanced Evaporative Air Conditioner, or DEVap for short, is a new technology that
has the potential to revolutionize the HVAC industry. The device combines the cooling power of
evaporation with the dehumidifying power of liquefied desiccants — the salt-like substance found
in “Do Not Eat” packets — to create an air conditioner that creates cold, dry air at a fraction of the
cost. Although not yet commercially available, the prototypes have demonstrated an astounding
90% reduction in energy use compared to traditional air conditioners.

AR8622 |BUILDING SERVICE III |2017 REGULATION|A.SIVARAMAN M.ARCH|PRIME CAP-KILVELUR 60

11.Solar-Powered Air Conditioning

Fig:Micro-Concentrator solar panels; via Chromasun

Typically, when the hot sun is beating down on a building, it is not reducing the air conditioning
bill, but that is exactly what Chromasun’s Micro-Concentrator makes possible. These compact,
rooftop panels contain special mirrored lenses, which automatically follow the sun’s path,
concentrating and capturing solar energy. That energy is then utilized by the building’s HVAC
system, converting peak sun loads into efficient air conditioning

AR8622 |BUILDING SERVICE III |2017 REGULATION|A.SIVARAMAN M.ARCH|PRIME CAP-KILVELUR 61

BUILDING AUTOMATION SYSTEM FOR LIFT AND ESCALATOR

“Pilots radio ahead when they have a problem. If they detect a problem with an oil pump in an
engine on a flight from London to Chicago, they can radio ahead and say ‘I need my oil pump
replaced when we land,’ and they can change the parts rapidly and put the plane back into service
without missing the next flight,” explains Smith. “They have expensive assets and a high cost of
failure. Now we can take advantage of that same technology and apply it to assets like elevators
and escalators.”

So far, IoT implementation for vertical transportation has revealed two key customer camps,
according to Jeremy Rainwater, senior vice president of existing installation and modernization for
Schindler: people who prize the benefits of improved performance, transparency and new
insights, and those who are more focused on cost savings. Today’s IoT-enabled elevators deliver
these 10 benefits and more.

1) Monitoring Operating Conditions

Like the Internet of Things (IoT)devices in other building systems, elevator IoT devices make
gathering data simple and effortless. Depending on the elevator manufacturer and model, your
IoT-enabled elevator might gather data in any of these areas, according to Charlie Slater, director
of field operations at American Testing and Inspection Services:

 Critical safety circuits

 Load weighing

 Number of trips

 Number of door cycles

 Wait times

 Traffic trends

 Ride analysis (acceleration and deceleration, jerk, bumps, vibration)

 Harmonic analysis (the harmonics of the machine, suspension members and

guiding members)

AR8622 |BUILDING SERVICE III |2017 REGULATION|A.SIVARAMAN M.ARCH|PRIME CAP-KILVELUR 62

2) Predictive Maintenance

The biggest immediate time-saver that IoT data fuels is improving your preventive maintenance
schedule and switching to more of a predictive maintenance model. The devices can monitor
changes in operating conditions, like heat, friction or noise, and use the changes to predict when
the elevator needs maintenance.

(Photo: Technician fix the lift or elevator in railway station of skytrain. Credit: SB7)
“If certain conditions are left unattended, they could result in equipment failure, and in turn cause
an unplanned disruption in a building,” explains Daniel Elez, senior vice president of service
business for KONE Americas. “IoT is allowing maintenance to become predictive and proactive vs.
reactive.”
Keeping track of wear and tear is another useful way to predict when and where maintenance will
soon become necessary, adds Smith. That could include door open-close cycles, how long the door
takes to close and how much power it draws to do so, how many times the elevator has to relevel,
acceleration speeds and even the physical distance the elevator has traveled. “We’re keeping
track of door cycles on a per floor basis so that we know which floors have the most use of the
doors. No matter what brand, the doors on elevators are the most problematic device because
they’re mechanical and they take a lot of abuse,” Smith explains.

AR8622 |BUILDING SERVICE III |2017 REGULATION|A.SIVARAMAN M.ARCH|PRIME CAP-KILVELUR 63

“People run into the doors and hold them open when they’re trying to close. We believe there’s a
correlation between the amount of abuse and the number of breakdowns and we want to make
sure we adjust our maintenance frequency to the doors that get the most use. Now we
can quantify it and say ‘Every X number of times the door cycles, we should schedule
maintenance,’” he adds.

3) Remote Diagnostics and Troubleshooting

The constant stream of data from the monitoring devices also enables manufacturers and other
elevator service professionals to diagnose problems at least partially before they even reach your
building, saving valuable on-site time that would otherwise have been wasted on testing and
troubleshooting.

BUILDINGS Checklist

Preventative Maintenance

Use this checklist to keep major building systems—HVAC, roofing, plumbing and lighting—in good
working order.
The technician can receive a complete diagnosis with corroborating information and suggested
actions ahead of time so that when they reach your building, they can spend all of their time
actually fixing the problem, Elez says.

“Without IoT, if it’s noticed that an elevator is out of service, a maintenance company would be
contacted to request a service call,” says Slater. “The elevator maintenance company would need
to dispatch a mechanic to visit the unit and hopefully diagnose the issue correctly. They may have
to order parts and have a return visit to perform the repair. If the diagnosis was incorrect, they
would have to start over again. With IoT, the elevator maintenance company knows immediately
and probably before the building does that the elevator is out of service.”

AR8622 |BUILDING SERVICE III |2017 REGULATION|A.SIVARAMAN M.ARCH|PRIME CAP-KILVELUR 64

4) Real-Time Notifications
IoT devices in elevators may even be able to catch problems before facilities managers or building
occupants notice anything is amiss. Remote monitoring and diagnostics can catch budding
problems when they start instead of waiting until the elevator is noticeably noisier or drawing a
spike in power.
“For example, Schindler can see that an elevator is on the third floor of a building with a switch in
the wrong position and can proactively contact the customer to resolve the issue, vs. the customer
having to call for service, get in the queue for a technician and have the technician arrive just to
find out that a switch needed to be turned,” Rainwater says. “This level of proactive service will
help us deliver even better performance and reliability by using data to identify and act on
potential issues even before our customers are aware of an issue.”

5) Behavioral Insights
Future elevator IoT devices should be able to gather data on the behavior of users and use that to
inform the unit’s behavior, Elez notes: “For example, instead of an unexpected influx of lobby
visitors, data can help inform systems when trains arrive nearby or large meetings or conferences
are ending, all to be prepared for lots of people arriving or departing a building.”

6) Avoided Downtime
There’s significant value in not having to drop everything to deal with an unexpected elevator or
escalator breakdown. Downtime for your vertical transportation should be rare, planned and
during off-peak hours.“Failure prediction is a big goal,” Smith says. “We want elevators to be
running a higher percentage of the time, but we also want to have planned downtime. You can’t
have 100 percent uptime because you’ll have to take it out of service to provide maintenance, so
we want to make sure that the right amount of maintenance is being provided.”

AR8622 |BUILDING SERVICE III |2017 REGULATION|A.SIVARAMAN M.ARCH|PRIME CAP-KILVELUR 65

 UNIT- 3

AIR CONDITIONING:

DESIGN ISSUES& HORIZONTAL

DISTRIBUTION OF SYSTEMS
Design criteria for selecting the Air conditioning system
for large building
 CHILLER SYSTEM DESIGN CONFIGURATION

1. Centralised Ducted “All Air Systems” Classified In To 3 Types:

1. Constant Air Volume Systems (CAV)

2. Dual Duct Systems,
3. Variable Air Volume Systems (VAV)

2. Central Fluid Based Hydronic Systems "all Air Systems” Classified

In To 3 Types:

A) Hydronic System ( All Water System)

B) Fan Coil System
C) Induction System
D) Variable Refrigerant Volume Systems (VRV)
E) Hybrid System

3. Decentralized Systems Classified in To 3 Types:

A) split systems
B) window
C) heat pumps
 CENTRALISED DUCTED “ALL AIR SYSTEMS”
CONSTANT AIR VOLUME SYSTEMS (CAV)
CONSTANT AIR VOLUME
(CAV) is a type of heating,
ventilating, and air-
conditioning (HVAC)
system.
In a simple CAV system,
THE SUPPLY AIR FLOW
RATE IS CONSTANT, BUT
THE SUPPLY AIR
TEMPERATURE IS VARIED
TO MEET THE THERMAL
LOADS OF A SPACE.
MOST CAV SYSTEMS ARE SMALL AND SERVE A SINGLE THERMAL ZONE, AND
CAV PRIMARY-SECONDARY SYSTEMS CAN SERVE MULTIPLE ZONES AND LARGER
BUILDINGS.

In SOME LARGE SIZE BUILDINGS, NEW CENTRAL CAV SYSTEMS ARE SOMEWHAT
RARE. DUE TO FAN ENERGY SAVINGS POTENTIAL, VARIABLE AIR VOLUME
SYSTEMS ARE MORE COMMON.
 CENTRALISED DUCTED “ALL AIR SYSTEMS”
CONSTANT AIR VOLUME SYSTEMS (CAV)

However, in small buildings

and residences, CAV SYSTEMS
ARE OFTEN THE SYSTEM OF
CHOICE DUE TO SIMPLICITY,
LOW COST, AND RELIABILITY.

Such small CAV systems

often have on/off control,
rather than supply air
temperature modulation, to
vary their heating or cooling
capacities.
There are two types of CAV systems that are commonly in use to modify the
supply air temperature:1. the TERMINAL REHEAT SYSTEM 2. THE MIXED AIR SYSTEM.
THE TERMINAL REHEAT SYSTEM COOLS THE AIR IN THE AIR HANDLING UNIT DOWN
TO THE LOWEST POSSIBLE NEEDED TEMPERATURE WITHIN ITS ZONE OF SPACES.
THE MIXED AIR SYSTEM HAS TWO AIR STREAMS, TYPICALLY ONE FOR THE COLDEST
AND ONE FOR THE HOTTEST NEEDED AIR TEMPERATURE IN THE ZONE.
 CENTRALISED DUCTED “ALL AIR SYSTEMS”
VARIABLE AIR VOLUME SYSTEMS (VAV)

Variable air volume (VAV) is a type of heating, ventilating, and/or air-

conditioning (HVAC) system.
The simplest VAV system incorporates one supply duct that, when in cooling
mode, distributes approximately 55 °f (13 °c) supply air.
Because the supply air temperature, in this simplest of VAV systems, is
constant, the air flow rate must vary to meet the rising and falling heat gains or
losses within the thermal zone served.
 VARIABLE AIR VOLUME (VAV)
A VAV terminal unit, often called a VAV box, is the zone-level flow control device.
It is basically a quality, calibrated air damper with an automatic actuator.

FEATURES
❑ Sophisticated solution
BENEFITS ❑ Insensitive to duct pressure
❑ Localize control & data backup ❑ Factory calibration possible
❑ Reduction in cabling ❑ No site calibration required (self
❑ Easy maintenance, fault traceability balancing system)
❑ System to work as Standalone / ❑ Duct design less critical
Networkable ❑ Modulating controls
❑ there by free from central system for ❑ Accurate pressure and air volume
local operation control
 CENTRALISED DUCTED “ALL AIR SYSTEMS”
DOUBLE DUCT SYSTEMS

Dual-duct systems generally vary the supply air temperature by mixing

two airstreams of different temperatures, but can also vary the volume of
supply air in some applications.
Dual-duct systems, contain the main heating and cooling coils in
parallel flow or series-parallel flow air paths with either:
(1)a separate cold and warm air duct distribution system that blends the air at
the terminal apparatus (dual-duct systems), or
(2) a separate supply air duct to each zone with the supply air blended to the
required temperature at the main unit mixing dampers (multizone).
 CENTRALISED DUCTED “ALL AIR SYSTEMS”

DOUBLE DUCT SYSTEMS

 CENTRAL FLUID BASED HYDRONIC SYSTEMS“ALL AIR SYSTEMS”
HYDRONIC SYSTEM S ( ALL WATER SYSTEMS)

TWO PIPE SYSTEMS

A two pipe system consists of fan coil units with single coils which are connected to
two pipes.

These two pipes, one supply and one return, are connected to supply lines in our
mechanical room.
Supply lines can either supply hot water or chilled water.

A building with a two pipe system is either entirely in the cooling mode or entirely
in the heating mode. It is not possible to cool some rooms while heating others.
 CENTRAL FLUID BASED HYDRONIC SYSTEMS“ALL AIR SYSTEMS”
HYDRONIC SYSTEM S ( ALL WATER SYSTEMS)

TWO PIPE SYSTEMS

Two-pipe system is usually operated in the heating mode in the Winter and the
cooling mode in the Summer.

Two pipe systems cannot handle simultaneous heating and cooling, and are not
acceptable where there are internal rooms with high internal gains, such as
computer rooms.

Two pipe systems are less complicated in the sense that there are fewer pipes,
coils, valves and controls.
 CENTRAL FLUID BASED HYDRONIC SYSTEMS“ALL AIR SYSTEMS”
HYDRONIC SYSTEM S ( ALL WATER SYSTEMS)

THREE PIPE SYSTEMS

In the three pipe system, hot water and chilled water are fed to each fan coil,
with a common return. This is somewhat more expensive than 2-pipe system,
since a third pipe must be run to each unit. Since the hot water and cold
water are mixed in the return, these inefficient systems are seldom installed
today
 CENTRAL FLUID BASED HYDRONIC SYSTEMS“ALL AIR SYSTEMS”
HYDRONIC SYSTEM S ( ALL WATER SYSTEMS)
FOUR PIPE SYSTEMS
A four pipe system has fan coil units with separate heating and cooling coils, as well
as separate pairs of heating and cooling pipes.
Hot water or chilled water is always available. The system is able to instantly switch
from the heating mode to the cooling mode, or vice versa, and can provide heating
to some rooms while simultaneously providing cooling to other rooms. It is very
flexible.
Disadvantages are that it is more complicated, with ultimately twice as many
control valves to maintain, and twice as much congestion due to piping. Four pipe
systems are more expensive.
 CENTRAL FLUID BASED HYDRONIC SYSTEMS“ALL AIR SYSTEMS”
FAN COIL SYSTEM

Fan coil systems consist of multiple

fan coil units, a piping system, chiller,
and boiler.

The fan coil units themselves are

comprised of a finned-tube coil, an
insulated drain pan under the coil to
collect condensate, a fan to move air
through the coil, filters, and a cabinet
to house these components.

Typically fan coils are either located

above ceilings and ducted to ceiling
diffusers, or under windows using
console units. Console units are
sometimes ducted through the wall
for ventilation air.

The chiller may be air-cooled

 CENTRAL FLUID BASED HYDRONIC SYSTEMS“ALL AIR SYSTEMS”
FAN COIL SYSTEM

The chiller may be air-cooled

(available in either a single packaged
unit, or in various split
configurations), or water-cooled in a
split configuration utilizing a cooling
tower.

Water-cooled chillers are more

efficient because they reject heat to
the wet bulb temperature of the
outside air, while air cooled chillers
reject heat to the normal dry bulb
temperature of the outside air.

Water-cooled chillers require

maintenance of the cooling tower.
For this reason we do not usually
recommends water-cooled chillers
for smaller systems.
CENTRAL FLUID BASED HYDRONIC SYSTEMS“ALL AIR SYSTEMS”

HYBRIDSYSTEM
CENTRAL FLUID BASED HYDRONIC SYSTEMS“ALL AIR SYSTEMS”

VARIABLE REFRIGRANT VOLUME SYSTEMS (VRV)

The system offers large outdoor capacities, greater energy

savings, easier installation, longer actual and total piping,
and more.

Individual control

Conventional systems air-condition a building as a whole,

whereas the VRV system air conditions each room
individually. Hence it is ideal for the constantly changing
occupancy of a typical building. Even further, precise level
control is possible that reacts to the exact conditions in
each room. Individual control promotes a far more
economical and efficient system.

Saves energy
Using the VRV for ventilation dramatically boosts energy efficiency.

Conserves space

Space efficiency is enhanced by the compact size of the individual units, the long maximum piping length, and the ability to
realize a large-scale air conditioning system with a single piping circuit.

Offers a wide selection of models

Lineup of heat pump types are 5 to 54 HP, and both in 2 HP increments*. Indoor units consist of 14 types with a total of 79
models. This wide selection of models makes it possible to build a system that perfectly suits the customer’s requirements
* Except for 5 HP (HEAT PUMP SYSTEM)
CENTRAL FLUID BASED HYDRONIC SYSTEMS“ALL AIR SYSTEMS”

VARIABLE REFRIGRANT VOLUME SYSTEMS (VRV)

Operates over a broad temperature range

The lower end of the operating temperature range in heating has been extended from –15°C to – 20°C.
CENTRAL FLUID BASED HYDRONIC SYSTEMS“ALL AIR SYSTEMS”

VARIABLE REFRIGRANT VOLUME SYSTEMS (VRV)

Provides superior design flexibility

•The extended maximum piping length gives more flexibility when designing the system.
•Layout changes can be made easily because the capacity of the indoor units can be up to 200% that of the outdoor units.
•New compressor technology eliminates the need for piping calculations, which shortens the time needed for design.
•Outdoor units can be placed on the roof where they have no effect on the design of the building interior.

Enhances ease of use

•Units are designed to operate quietly, and are also equipped with a function for silent operation especially at night.
•The controller is easy to operate and has many useful functions. Units can be controlled in each individual room.

Delivers ultimate reliability

•The self-diagnostic system identifies problems within the system quickly and accurately.
•The Auto Restart function ensures that operation is restored with the previous settings even if the power has been shut
off.
•Units are controlled in each individual room, so local malfunctions does not cause the entire system to shut down.

Simplifies installation
•The lightweight, compact units can be transported using a regular lift.
•Units can be installed on each floor.
•The pipes are few in number, making layout simpler.
•Inspection after installation is straightforward.
CENTRAL FLUID BASED HYDRONIC SYSTEMS“ALL AIR SYSTEMS”

VARIABLE REFRIGRANT VOLUME SYSTEMS (VRV)

Outdoor Units

Specifications

➢Range minimum (5HP) 4.15 TR to maximum

(54HP) 42 TR
➢Compact -space saving
➢Efficient & high performance inverter type &
constant speed type scroll compressors

➢High Coefficient of Performance (COP)

➢Operates on environment friendly refrigerant
R-410A
➢Design flexibility- suitable for large sized
buildings

➢Long piping length up to 165 meters

➢Higher external static pressure condenser fan
➢Automatic test operation function

➢Memory function –Eliminate malfunctions

➢Nighttime quite operation function
➢High combination ratio (Indoor unit vs.
Outdoor unit)

➢Can be Configured with building management

control system –optional
➢Equipped with EPD (Electrical Protection
Device)
ENERGY EFFICIENCY IN AIR
CONDITIONING SYSTEM
 IBMS CONTROL ROOM
 The IBMS Control room is designed to monitor & control all of the
subsystems & provide the following functionality.

 SAFETY FUNCTIONS ,
 SECURITY FUNCTIONS,
 AUTOMATION OF ALL GENERAL FUNCTIONS,
 MANAGING AVAILABILITY & DISTRIBUTION OF RESOURCES SUCH AS
COOLING, WATER & ELECTRICITY,
 ENERGY OPTIMIZATION,
 TENANT BILLING
 CENTRAL MONITORING OF ALL THE PLANTS & EQUIPMENTS ,
 FACILITATE CONTROL FROM REMOTE LOCATION USING INTERNET /
INTRANET

 All the systems is designed with ‘open connectivity’ in mind in order to cater
to all the future building connectivity with various third party systems.
 WEB ACCESS used as the common
interface for multiple systems:

 HVAC (LON) local operating

network

 Lighting (LON)

 Infrastructure (Modbus)

 Energy management system

(EMS)

 Facility management system(FMS)

 WEB ACCESS collects and records

real time data for:
 Energy Usage

 Equipment Status

 Controls
 WEB ACCESS records data to RDBMS database for use by the ENERGY
MANAGEMENT SYSTEM (EMS).

 WEB ACCESS CLIENT provides interface to the EMS.

 Advanced Charting of Energy Usage.

 Trend Analysis
 INTEGRATED BUILDING MANAGEMENT SYSTEM (IBMS)
IN HEATING VENTILATION AIR CONDITIONING (HVAC)
CHILLER PLANT MANAGEMENT
Chiller/pumps sequencing.
Chilled Water Return Header Temperature
Optimization of chiller use.
Integration with chiller microprocessor panel
BMS Integration for monitoring
Facility manager for Chillers to view the data remotely and in graphical format
Includes field accessories such as sensors, valves Etc (Depends on project specification)
 chilled water is often used to cool a building's air and equipment, especially in situations
where many individual rooms must be controlled separately, such as a hotel.
 A chiller lowers water temperature to between 40° and 45°F before the water is pumped
to the location to be cooled.
Cooling tower valve open Chilled water supply & condenser water return
motorized butterfly valve open

Condenser pump open

Chilled water supply condenser water return

flow switch confirm
Switch on cooling tower pan

Primary pump on chiller on

 WEB ACCESS records data to RDBMS
database for use by the ENERGY
MANAGEMENT SYSTEM (EMS).
 AIR COOLED CHILLERS

 A heat exchanger using air, refrigerant, water & evaporation to transfer

heat (BTUs) to produce air conditioning ( measured in tons).

 Chiller is comprised of an evaporator, compressor, condenser & expansion

valve system

 There are 3 primary pumps, two working & one stand by on a common
pipe line, Any pump should be workable with any chiller,

 There are motorized isolating valves which should be activated across the
working chiller.

 primary should be started & then command should be given to the

motorized isolating valve to open.

 After open position of the valve is identified, then the command to start
the chiller will be issued,

 chiller must have a water flow switch which will finally determine to allow
the chiller to run or not.
 AIR COOLED CHILLERS

 plant manager is planned for the chillers & will be integrated with BMS to
monitor the chiller parameters.

 Through BMS, chiller will be switched ON/OFF & will be hardwired.

 chiller sequencing through differential temperatures on the supply &

return header.

 the above data log will be used for BTU meter to be installed in return
water header after the de-coupler line from the chiller.

 outside air temperature & humidity sensor will be installed as a global

reference for all HVAC measurements.

 secondary pumps are run by VFDs,

 pressure transducers & the VFDs are packaged & supplied by the HVAC
contractors.
AIR HANDLER, OR AIR HANDLING UNIT (AHU),

 An air handler, or air handling unit (often abbreviated to AHU),is a

device used to condition and circulate air as part of a heating,
ventilating, and air-conditioning (HVAC) system.

 controls temperature,
 controls humidity,
 controls pressure & air exchange
 FIELD DEVICE THAT HAS IBMS SCOPE
1. TEMPERATURE SENSORS
2. CO2 SENSORS,
3. DIFFERENTIAL PRESSURE SWITCH.

1. TEMPERATURE SENSORS
 RESISTANCE TEMPERATURE DETECTORS (RTDS), are sensors
used to measure temperature by correlating the resistance of the rtd
element with temperature.
 FEATURES & BENEFITS
 Monitors temperature, humidity, pressure, air quality and air velocity
 Available in a wide range of sensing values,
 Supports all popular control signals,
 Provides high accuracy for best energy savings,
 Installs easily with flexible mounting accessories.
 Quick-sensing response time,
 Requires no maintenance.
B. CO2 SENSORS
 A carbon dioxide sensor or CO2 sensor is an instrument for the
measurement of carbon dioxide gas.
 The most common principles for CO2 sensors are infrared gas sensors
(NDIR) and chemical gas sensors.
 Measuring carbon dioxide is important in monitoring
indoor air quality and many industrial processes.
 APPLICATIONS
 Excellent performance CO2 Sensor, for use in a wide range of
applications, including air quality monitoring, smoke alarms, mine and
tunnel warning systems, greenhouses, etc.
 The sensor is easy to use and can be easily incorporated in a small
portable unit.
 FEATURES
 High Sensitivity
 Detection Range: 0 - 10,000 ppm (parts per million) CO2
 Response Time: <60s
 Heater Voltage: 6.0V
 Dimensions: 16mm Diameter, 15mm High excluding pins, Pins - 6mm High
C) DIFFERENTIAL PRESSURE SWITCH

 FILTER MONITOR OR FLOW SWITCH for air, non-combustible, non aggressive

gases in air conditioning and ventilating installations.

 APPLICATIONS
 Monitoring air filters and ventilators
 Monitoring industrial cooling-air circuits
 Overheating protection for fan heaters
 Monitoring flows in ventilation ducts
 Controlling air and fire-protection dampers
 Frost protection for heat exchanges
Kind of pressure overpressure, relative
Pressure connection plastic connection piece for 5 mm (internal) hose

Electrical connection AMP connector 6,3x0,8 (DIN 46244) or screw terminals

Protection class IP54

Sensing element material ABS + Silicon
Media temp. -20 ... 85 oC
Ambient temperature -20 ... 85 oC
Switch function/capacity SPDT switch 240 Vac; 1,5 A (0.4)A

Certificates CE0085AR0013 according EC Gas Appliance Directive EU/2009/142/EG and DIN EN 1854

Max. pressure 10000 Pa

 VARIABLE FREQUENCY DRIVE (VFD)
 This device uses power electronics to vary the frequency of input power to the
motor, thereby controlling motor speed.
 BENEFITS OF VFD
As VFD usage in HVAC applications has increased, fans, pumps, air handlers,
and chillers can benefit from speed control. Variable frequency drives provide
the following advantages:
 reduction of thermal and mechanical stresses on motors and belts during
starts,
 low motor starting current,
 Energy savings,
 simple installation,
 high power factor,
 lower KVA.
 BTU METERING
 Air conditioner capacity is measured by "BTU". BTU stands for British Thermal
Units.
 BTU Metering

 Measurement is carried by placement matched pair temperature sensors in

the supply and return water lines of the AHU and flow is monitored.
 The flow and temperature readings are used to evaluate the BTU
consumed on a continuous basis.
 All the parameters are transferred to the central system through the M-
BUS to monitor the AHU’s efficiency / BTU Consumed.
 BTU METERING CONSISTS OF

 Flow meter inline turbined impellers / Jet type/Electro magnetic/ultrasonic types

 Heat Integrators
 Matched pair temperature sensor with pocket for insertion
 Local data logging
 Local digit LCD display
 M BUS O/P

•M-BUS Automation Gatway