This is an overview of introduction of heating and air conditioning condition sytem in the application of civil and architectural works.

1. Heating and Air-Conditioning
Fundamentals
A lecture series of Prof. Tomas Ucol-Ganiron Jr
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2. Objectives
• Describe the difference between the
high and low sides of the system
• List the major heating and air-
conditioning parts and describe
their operation
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3. Sources of Heat
• The system adds heat in the winter
• Removes it in the summer
• Sources of heat
• Passengers
• Outside air
• Road
• Engine
• Catalytic converter
• Sunlight
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4. Heating
• Engine coolant is routed to heater core
• Air passes over fins of the heater core
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5. Air Distribution System
• Moves heat between different locations
• Controls air volume, temperature,
quality, and location
• Plenum housing: case assembly
• Combined or split
• Air doors
• Open and close to control air flow
• Carbon air filter
• Often replaced with screens
• Control head: relays A/C system demands
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6. Air Conditioning
• Air in passenger compartment is cooled, dried,
and circulated
• Heat is removed from inside to outside
• Modern cars get better freeway fuel economy
with windows up and air-conditioning on
• Above 40 mph: more gas used with
windows down
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7. Air-Conditioning Principles
• Must be a transfer of heat for refrigerant to
change state
• Liquid absorbs heat as changes to gas
• Vapor releases heat as changes to liquid
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8. Heat Transfer
• Heat flows to anything with less heat
• Convection
• Heat rises
• Heat always flows from hot to cold
• Radiation
• Example: heat from the sun
• Evaporation
• Moisture absorbs heat as it is
vaporized
• Example: perspiration
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9. Humidity
• Low humidity
• Permits heat to be taken away
from the human body
• Evaporation and perspiration
• High humidity
• Makes evaporation difficult
• People feel as comfortable at 79°F
with 30% humidity as at 72°F at 90%
humidity
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10. States of Matter
• Common matter exists in three
states depending on temperature
• Solid
• Liquid
• Gas
• Solid heated above freezing melts
• Becomes a liquid
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11. Latent Heat
• Sensible heat
• Goes into matter
• Results in temperature increase
• Latent heat
• Extra heat required for matter to change
state
• Cannot be recorded on a thermometer
• Additional concepts
• Quantity of heat
• Vaporization
• Condensation
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12. CE 331-Environmental 12
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13. Air-Conditioning System
Operation
• Closed system
• Four major devices
• Compressor
• Condenser
• Evaporator
• Metering device
• Refrigerant circulates among devices
• Changing pressure and state of refrigerant
regulates cooling cycle operation
• Four stages: compression, condensation,
expansion, and vaporization
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14. Absorbing Heat
• Process
• Liquid refrigerant is circulated to the evaporator
• Loses pressure as it exits the metering
device
• Absorbs heat from inside of car
• Boils and vaporizes
• Pressurized again
• Gives off heat to outside air
• Each cycle through evaporator absorbs at
least 25° of heat from air blowing across it
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15. Reducing Humidity
• Sources
• Outside air
• Breathing of passengers
• Moisture in the air condenses on evaporator fins
• Drained off through the floor as water
• System does not cool air as much when humidity
is high
• Defroster operation
• Dried cool air moves through heater core
before it is blown onto the windshield
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16. Compressing the Refrigerant
• Vaporized refrigerant pulled from evaporator to
compressor
• Compressors are driven by a belt from
the crankshaft
• Pressurizes heated refrigerant,
increasing its temperature
• Compressor clutch
• Electromagnetic clutch connects and
disconnects from the crankshaft pulley
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17. CE 331-Environmental 17
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18. Home Cooling

19. Humidity in air
• Relative Humidity
• A measure of
much water is in
the air relative to
the maximum
amount of air can
heat at that
temperature.
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20. CE 331-Environmental 20
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http://www.ae.iastate.edu/Ast473/Lectures/%285%29Psychrometric_Chart/sld024.htm

21. Principle
A. Expansion Valve
B. Compressor
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22. Arrangement
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23. TYPES OF AIR
CONDITIONERS
• Room air conditioners
• Central air conditioning systems
• Heat pumps
• Evaporative coolers
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24. Air Conditioning
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25. Room air conditioner
• 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
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26. CE 331-Environmental 26
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27. Central Air conditioning
• 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
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28. Types of Central AC
• 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
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29. 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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30. Total Air Conditioning
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31. • 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.
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32. Sizing Air Conditioners
• 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
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33. Energy Consumption
• 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.
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34. Energy Efficiency
• 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
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35. Energy Efficiency
• 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
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36. Room Air Conditioners
• 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
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37. Central AC
• 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
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38. Energy Saving Methods
• 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.
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39. Numerical Problem
• A EER from 5.0 to 9 saving and pay
back period
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