Home Cooling
EGEE 102
Function of an Air 2
conditioner
Humidity in air 3
Relative Humidity
A measure of of
much water is in
the air relative to
the maximum
amount air can
hol at that
tmperature
4
http://www.ae.iastate.edu/Ast473/Lectures/%285%29Psychrometric_Chart/sld024.htm
Principle
A. Expansion Valve
B. Compressor
5
Arrangement 6
TYPES OF AIR 7
CONDITIONERS
Room air conditioners
Central air conditioning systems
Heat pumps
Evaporative coolers
Air Conditioning
8
Room air conditioner 9
Room air conditioners cool rooms
rather than the entire home.
Less expensive to operate than
central units
Their efficiency is generally lower than
that of central air conditioners.
Can be plugged into any 15- or 20-
amp, 115-volt household circuit that is
not shared with any other major
appliances
10
1
Central Air conditioning 1
Circulate cool air through a system
of supply and return ducts. Supply
ducts and registers (i.e., openings in
the walls, floors, or ceilings covered
by grills) carry cooled air from the
air conditioner to the home.
This cooled air becomes warmer as
it circulates through the home; then
it flows back to the central air
conditioner through return ducts
and registers
1
Types of Central AC 2
split-system
an outdoor metal cabinet contains the condenser
and compressor, and an indoor cabinet contains
the evaporator
Packaged
the evaporator, condenser, and compressor are all
located in one cabinet
Large air conditioning
systems
Outside air is drawn in,
filtered and heated
before it passes through
the main air conditioning
devices. The colored lines
in the lower part of the
diagram show the
changes of temperature
and of water vapor
concentration (not RH) as
the air flows through the
system.
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1
Total Air Conditioning 4
1
5
Variable fresh air mixer and dust and pollutant
filtration.
Supplementary heating with radiators in the outer
rooms and individual mini heater and
Humidifier in the air stream to each room.
1
Sizing Air Conditioners 6
how large your home is and how
many windows it has;
how much shade is on your home's
windows, walls, and roof;
how much insulation is in your
home's ceiling and walls;
how much air leaks into your home
from the outside; and
how much heat the occupants
and appliances in your home
generate
1
Energy Consumption 7
Air conditioners are rated by the
number of British Thermal Units (Btu)
of heat they can remove per hour.
Another common rating term for air
conditioning size is the "ton," which
is 12,000 Btu per hour.
Room air conditioners range from
5,500 Btu per hour to 14,000 Btu per
hour.
1
Energy Efficiency 8
Today's best air conditioners use 30% to 50% less
energy than 1970s
Even if your air conditioner is only 10 years old, you
may save 20% to 40% of your cooling energy costs
by replacing it with a newer, more efficient model
1
Energy Efficiency 9
Rating is based on how many Btu
per hour are removed for each
watt of power it draws
For room air conditioners, this
efficiency rating is the Energy
Efficiency Ratio, or EER
For central air conditioners, it is the
Seasonal Energy Efficiency Ratio, or
SEER
2
Room Air Conditioners 0
Built after January 1, 1990, need have an EER of
8.0 or greater
EER of at least 9.0 if you live in a mild climate
EER over 10 for warmer climates
2
Central AC 1
National minimum standards for central air
conditioners require a SEER of
9.7 for single-package and
10.0 for split-systems
Units are available with SEERs reaching nearly 17
2
Energy Saving Methods 2
Locate the air conditioner in a window or wall
area near the center of the room and on the
shadiest side of the house.
Minimize air leakage by fitting the room air
conditioner snugly into its opening and sealing
gaps with a foam weather stripping material.
2
Numerical Problem 3
A EER from 5.0 to 9 saving and pay back period
