BAZE UNVERSITY, ABUJA

DEPARTMENT OF MECHANICAL
ENGINEERING.

MCE315 DESIGN STUDIES 1

REPORT ON EXPERIMENT

AIR CONDITIONER

PREPARED BY
BUKOLA EMMANUEL
ID: BU/18C/ENG/3453
TABLE OF CONTENTS:
 Objectives
 Apparatus
 Theory
 Definitions
 Descriptions of apparatus
 Formula
 Specifications
 Table and calculations
 Images
Objective:
a) To determine the COP of air conditioning system.
Apparatus:
 Air heaters,
 Blower fan,
 Temperature scanners,
 Energy meters
 Rotameter
Theory:
Air conditioning plant consists of a number of components (e.g. fans, filters, hea
t exchangers, humidifiers, etc.) enclosed in a sheet metal casing. Intake to the pl
ant is usually from a clean external atmosphere (plus, in some cases, air recalcul
ated from the building) and delivery from the plant is via ducting to suitable dist
ribution points. Alternatively small self-contained packaged units may be used t
o air condition individual rooms or enclosures. In any air conditioning system, t
emperature and humidity are controlled by thermodynamic processes. Dependi
ng on the season, the air conditioning processes involve cooling, heating, humid
ification and dehumidification of air. Other aspects such as air movements, circ
ulation, purification etc. are obtained by installing suitable fans, blowers, ductin
g and filters.

This equipment is designed to demonstrate different air conditioning processes s

uch as cooling, heating, humidification, etc. required for different seasons of the
year.

It consists of following parts:

Compressor: The low pressure and temperature of refrigerant from the evaporat
or is drawn into the compressor through the inlet and suction valve as it is comp
ressed to high temperature and pressure. This high temperature and pressure vap
our refrigerant is discharged into the condenser through the delivery pipe.
Refrigerant: R22 is used as a medium to undergo vapour compression refrigerati
on cycle for air conditioning system.

Condenser: The condenser consists of pipe in which the high pressure and temp
erature refrigerant is cooled and condensed. As the refrigerant passes through th
e condenser it gives up heat to its surrounding which consists of condensing me
dium which is air or water.
Cooling Fan: To blow atmospheric air on the condenser to help cooling of refrig
erant in the condenser.

Receiver: The condenser liquid refrigerant from the condenser is stored in a ves
sel known as receiver from where it is supplied to evaporator through expansion
valve or refrigeration control valve.

Expansion valve: Also called as throttle valve and its use is to allow the refriger
ant under high temperature and pressure to pass at controlled rate after reducing
its high temperature and pressure some of the refrigerant evaporates as it passes
through the expansion valve and the graded portion is vaporized in the evaporat
or at low temperature and pressure.

Capillary Tube: Performs the same function as the throttle valve. It is a fixed le
ngth small bore transparent tubing installed between condenser and evaporator-
used to demonstrate the working of the Throttle Valve. During the refrigeration
experiment. Switching can be realized by suitable connecting/valve system.

Evaporator: Consisting of coils of pipe in which the liquid vapour refrigerant at

low pressure and temperature is evaporated and changed to the vapour refrigera
nt at low temperature and pressure. In evaporating the liquid vapour refrigerant
absorbs the latent heat of vaporization from the medium which is to be cooled.

Definition:
a. Dry Air: Mechanical mixture of oxygen, Nitrogen, Carbon dioxide etc.
 b. Moist Air: Mixture of dry air and water vapour.

c. Saturated Air: Is such a mixture of dry air and water vapour when the air
has diffused the maximum amount of water vapour onto it.

d. Degree of Saturation: Is the ratio of actual mass of water vapour in a unit

of dry air to the mass of water vapour in the same mass of dry air when it
is saturated at the same temperature.

e. Humidity: Is the mass of water vapour present in one kg of dry air expres
sed in gm per Kg of dry air.

f. Absolute Humidity: Is the mass of water vapour present in 1m3of dry air,
expressed in gm per cubic meter of dry air.

g. Relative Humidity: Is the ratio of actual mass of water vapour in a given

volume of moist air to the mass of water vapour in the same volume of sa
turated air at the same temperature and pressure.

h. Dry Bulb Temperature: Is the temperature of air recorded by a thermomet

er when it is not affected by the moisture present in the air.

i. Wet Bulb Temperature: Is the temperature of air recorded by a thermomet

er when its bulb is surrounded by a wet cloth exposed to the air.

Description of Apparatus:
The apparatus consist of a cooling coil which is a part of the AC System Coolin
g Coil of the vapour compression refrigeration system consisting of Compressor
Condenser, Throttle/Capillary Tube, the system works on R-22.
 The air conditioning duct is made up of MS sheet which is thermally insu
lated and acrylic sheet is provided at the front for visualization purpose an
d is fixed on a rigid frame.
 Two different types of throttling processes are there such as thermostatic
expansion and capillary.
 Either one of the throttling method need to be compulsory operated.
 Air heaters are provided at the inlet and outlet of air which are placed on
either sides of the evaporator.
 Two fans are provided at the inlet and delivery of air.
 At different points temperatures are measured by using the RTD sensors
which are connected to the temperature scanner which in detail are explai
ned.
  Doors are there at the bypass line to change the system to perform in both
closes cycle and open cycle modes.
 Pressure gauges are connected which reads the upstream high pressure an
d downstream low pressure of the compressor.
 Energy meter will read the power consuming point of air conditioning un
it.
Formulae
i. Theoretical COP
h 1−h 4
COPtheo =
h 2−h 1
ii. Ton of refrigeration
Compressor wattage (W):
n x 1000 x 60 x 60
W= KW
3200 x t
Where,
n= Number of blinks of energy meter disc.
t = The time taken by the Energy meter for n blinks, in seconds.
Tonof Refrigeration=COP theo ×Compresser wattage∈KW

iii. Carnot COP

T 2+273
COPcarnot =
(T 3+273)−(T 5+273)

Specifications:
Compressor : 1ton Rotary type.
Evaporator : 9”x13”x3rows.
Condenser : 23”x16”x2rows. (Air Cooled)
Heater : Air heater (300W) (4 nos.)
Heater controller : Controller Knobs.
Temperature sensors : K-type thermocouples
Temperature scanner : 8Channel (2nos.) (0-199.9C)
Energy meter : 32oo IMP/KW-Hr
Fan : Suction type (2nos.)
Fan controller : Controller Knobs.

Temperature Points:

T1=Compressor inlet/Evaporator outlet

T2=Compressor outlet/Condenser Inlet
T3=Condenser outlet/throttling inlet
 T4=Throttling outlet/Evaporator inlet
T5=Air inlet
T6=Air outlet
Energy meters:

W1: Power of compressor.

W2: Power of heaters
Pressure points
HP=High pressure
LP=low pressure

Observation
Table

Compresso Time
Time E r Wattage per
lapsed W blinks
SN Flow ra
o. ( sec ) T1 T2 T3 T4 T5 T6 te (R22)
1 3000 26.9 26.9 26.9 26.9 -
14.6 25.5 34.0 03.2 26.2 17.7 10 675 5s

Type of Th Theoretica
rottle h1 h2 h3 h4 l COP Carnot COP Ton of Ref.
Thermosta 2468.3 141.4
t 5 2441.7 2 141.42 −87.31 38.27 k −5.89 ×10 4

Expansion

Calculations
 i. Theoretical COP
2468.35−141.42
COPtheo =
2441.7−2468.35
¿−87.31

ii. Ton of refrigeration

Compressor wattage (W):

N=3
T= 5s
3 x 1000 x 60 x 60
W= =675 KW
3200 x 5

TR=−87.31× 675=−5.89× 104

iii. Carnot COP
25.5+ 273
COPcarnot = =38.27 κ
(34.0+273)−( 26.2+273)

IMAGES:
PRECATIONS
1. Make sure you switch off the air conditioner before you leave
2. Allow the air conditioner to run for a while before you start taking
readings
3. Do not put for hand on the fan or tamper with the compressor
4. Disconnect all power sources when tuning the AC
5. Make sure the power cord of the AC is long enough, do not use an en
extension cord to power the AC.