2. Refrigeration
• It can be defined as the process of transferring heat
from a low temperature region to a high temperature
region.
• In other words it is the process of cooling a
substance.
• This can be achieved only if the heat is removed from
that substance.
3. Principle of refrigeration
The principle of refrigeration is based on second law of
thermodynamics. It states that heat does not flow from a low
temperature body to a high temperature body without
the help of an external work.
4. Principle
Since the heat has to be
transferred from a low
temperature body to a
high temperature body
some external work has
to be done according to
the second law of
thermodynamics. This
external work is done
by means of
compressor, condenser
etc.
This external work is
done by means of
compressor, condenser
etc.
5. Terms in refrigeration
1. Refrigerator:
It is a machine used to extract heat from a body at low
temperature and reject this heat to a body at high temperature.
Thus it cools the body.
2. Refrigerant:
It is substance, which is used as a working fluid in refrigerators.
The refrigerant has low boiling point, which means that it
vaporizes at low temperature and takes away the heat from a
substance.
6. 3. Capacity of Refrigerator:
It is defined as the rate at which heat can be removed from the
cold body.
4. Refrigeration Effect:
It is defined as the ratio of the quantity of heat removed to the
time taken.
Refrigeration Effect = Heat removed / Time taken
5. Coefficient of Performance (COP):
It is defined as the ratio of heat absorbed in a given time
(Refrigeration Effect) to the work done
COP = Refrigeration Effect / Work done
8. Working Principle
• During evaporation, the refrigerant absorbs its latent heat of
vaporization from the material that is to be cooled. Thus the
body is cooled in the evaporator .
Then the low pressure vapor refrigerant enters the
compressor and the cycle is repeated. Thus a material is cooled
in vapor compression system
9.
10. Air Condtioning
• Air conditioning is the process of altering the properties
of air (primarily temperature and humidity) to more
favorable conditions.
• The control of these conditions may be desirable to maintain
the health and comfort of the occupants, or to meet the
requirements of industrial processes irrespective of the
external climatic conditions
12. TYPE OF AIR-CONDITIONING
1) Window air-conditioning system
To install one of these units, you need the space to make a
slot in the wall, and there should also be some open space
behind the wall.
when the summer heat dies down, these units can be easily
removed for storage, and you can use the window sill for
other purpose
13.
14. 2) Split Air-Conditioning System :
• 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.
15.
16. 3) Centralized Air-Conditioning System :
The central air conditioning plants or the systems are used when
large buildings, hotels, theaters, airports, shopping malls etc. are
to be air conditioned completely.
17.
18. 4) Packaged Air-Conditioning System :
The packaged air conditioners are used for the cooling
capacities in between split air conditioners and centralised air
conditioners.
