Air Conditioning System
3rd year 2nd sem b.tech (agril. Engg.) Student
The air conditioning is that branch of
engineering science which deals with
the study of conditioning of air i.e.
supplying & maintaining desirable
internal atmospheric condition for
human comfort, irrespective of
Air Conditioner Work
Air conditioners use chemicals that easily
convert from a gas to a liquid and back again.
This chemical is used to transfer heat from
the air inside of a home to the outside air.
The machine has three main parts. They are
a compressor, a condenser and an
evaporator. The compressor and condenser
are usually located on the outside air portion
of the air conditioner. The evaporator is
located on the inside the house, sometimes
as part of a furnace. That's the part that heats
The working fluid arrives at the
compressor as a cool, low-pressure gas.
The compressor squeezes the fluid. This
packs the molecule of the fluid closer
together. The closer the molecules are
together, the higher its energy and its
The working fluid leaves the compressor
as a hot, high pressure gas and flows
into the condenser. If you looked at the
air conditioner part outside a house, look
for the part that has metal fins all around.
The fins act just like a radiator in a car
and helps the heat go away, or dissipate,
Classification of Air Conditioning Systems
Air conditioning systems are divided into
three types as followed:
Unitary Packaged Systems.
Central (Hydronic) Systems.
use a self-contained ,
factory-made air conditioner
to serve one or two rooms
(e.g. room/ window air
conditioner and split-type
It uses vapor compression
cycle directly to cool the
indoor air for small loads.
Unitary Packaged Systems
similar in nature to
individual systems but
serve more rooms or
even more than one
floor, have an air system
consisting of fans,
coils, filters, ductwork
and outlets (e.g. in small
restaurants, small shops
and small cold storage
Central (Hydronic) Systems
Basically consists of three major
◦ Air system – air handling units (AHU), air
distribution (air duct) system and
◦ Water system – chilled water system, hot
water system, condenser water system.
◦ Central plant – refrigeration (chiller) plant,
Air Handling Units (AHU)
Air Distribution System (Air Duct)
An air-handling unit (AHU) is the basic
piece of equipment used in an air system.
It can be either a field-assembled built-up
system or a factory-made unit.
Ducts are used in heating, ventilation, and air
conditioning (HVAC) to deliver and remove air.
These needed airflows include, for example,
supply air, return air, and exhaust air
Click on the picture to review the animation.
Chiller Central plant )
Chillers are a key component of air
conditioning systems for large
buildings. They produce cold water to
remove heat from the air in the
Common Types of Chillers
◦ Mechanical Compression.
◦ Absorption Chillers.
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
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
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
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
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
Minimize air leakage by fitting the
room air conditioner snugly into its
opening and sealing gaps with a foam
weather stripping material.
The Goal Of A.C System Design
The goal of an air conditioning system design is to
achieve a highly quality system that functions effectively
and is energy-efficient and cost-effective.
The following are essential for a system to function
All design criteria are fulfilled, and the
requirements of the owner and the user are
A good indoor air quality is provided.
The system is reliable and has adequate fire
protection level (e.g. smoke management).
Air Conditioning System Selection
When considering and selecting an air conditioning
system, the designer must understand the building
and the client’s requirements and try to study and
evaluate the following factors:
Building location, surrounding environment
and external climate
Uses and functional requirements of the
Client’s budget, investment policy and
expected quality of service
Air Conditioning System Selection
The designer should consider various system options and
recommend one or several that will be likely to perform as
desired. Some of the selection criteria include
Performance requirements – on comfort, noise, control options,
flexibility and meeting requirements of local regulations/codes.
Capacity requirements – range of capacity, multiple units, zoning, etc.
Spatial requirement – plant room space, space for ducting and piping
(vertical shafts),space for terminal equipment.
Costs – initial cost, operating cost and maintenance cost.
Energy consumption – for both economic and environment reasons.
System qualities – e.g. aesthetics, life, reliability and maintainability.
THANK YOU FOR YOUR
For any comments.