deep details about the Refrigiration and air conditioning made by abhishek singh for the new comers engineers

1. Refrigeration and Air
Conditioning
Prepared By :
MR. ABHISHEK SINGH

2. Heat Pump and Refrigerator
Principle
 Heat Pump: Device that absorbs heat
from cold body and delivers it to hot
body
 Refrigerator: Device that absorbs heat
from cold body and delivers it to
surroundings.

3. Refrigerator Definition
 Device used to maintain low
temperature below atmospheric
temperature within required space.
 ‘Method of reducing the temperature
of a system below surrounding
temperature and maintains it at lower
temperature by continuously
abstracting heat from it.’

4. Applications
 Storage and transportation of food.
 Preservation of medicine and syrups.
 Manufacturing of ice, photographic
films.
 Liquefaction of gases like N, O, H
 Comfort

5. Properties of Refrigerant
 High latent heat of evaporation and
low specific volume.
 Good thermal conductivity for rapid
heat transfer.
 Non-toxic, non-flammable, non-
corrosive.
 Low saturation pressure.
 High COP.
 Economical

6. Refrigerants
 Medium to absorb and reject heat
from required space and to the
surrounding respectively.
 A kind of working fluid for refrigeration
cycle.

7. Refrigerants Used
NH3: Highly toxic flammable, good
thermal properties, highest
refrigerating effect. Used for industrial
and commercial refrigeration system
like in ice plants, cold storage units.
Co2: Color-less, non-toxic, non-
flammable and non-corrosive. Used in
marine refrigeration.
Air: Economical, non-toxic, low COP.
Used in air craft refrigeration.

8. Refrigerants Used
 R11/Trichloro-monofluro methane/Freon-
11: non-toxic, non-flammable. Used in office
building air conditioning.
 R12/Dichloro-difluro methane/Freon-12:
non-toxic, non-flammable, non-corrosive,
high COP. Used in domestic refrigeration.
(VCRS)
 R22/Monochloro-Trifluro methane/Freon-
13: non-toxic, non-flammable, non-explosive,
less compressor displacement. Used in
commercial and industrial applications.

9. Unit of refrigeration
 One ton of refrigeration is defined as
“Refrigerating effect produced by
melting of 1 ton of ice from and at zero
degree C in 24 hours”
 “Amount of heat required to removed
in order to form one ton of ice in 24
hours from water at Zero degree C”

10. Coefficient of Performance
(COP)
 It is defined as Ratio of refrigerating
effect to the work done by compressor
to compress the refrigerant in the
compressor.
 Inverse of efficiency of heat engine.
 Its value is always greater than unity.

11. Types of Refrigerators
Natural Refrigeration: In natural
refrigeration, cooling effect produced by
evaporation of liquid or sublimation of
solids.
Mechanical Refrigeration: Refrigeration
effect is produced by external
mechanical energy or heat energy
source.
Types of Mechanical Refrigators:
Air Refrigerator
Vapour Absorption Refrigerator (VAR)
Vapour Compression Refrigerator (VCR)

12. Vapour Compression Refrigerator
(VCR)
•It Uses vapour as
a refrigerant which
condenses and
evaporates
alternatively.
•In evaporation it
absorbs latent heat
from the space to
be cooled while in
condensation, it
rejects heat to
atmosphere.

13. P-V and T-S Diagram for VCR

14. Functions of Various
components of VCR
 Compressor: To remove vapour from
evaporator and increase the pressure and
temperature, to be condensed in condenser.
 Condenser: Surface for heat transfer from
hot refrigerant vapour to condensing medium.
 Expansion valve: To provide the proper
amount of liquid refrigerant and reduces
pressure of liquid refrigerant entering the
evaporator.
 Evaporator: To provide a heat transfer
medium through which low temperature liquid
refrigerant can absorb heat from the space to
be cooled.

15. Domestic vapour Compression
refrigerator:
•Consists of and
evaporator installed in
freezing compartment.
•One end of evaporator is
connected to suction side
of the compressor and
other to the condenser
through the throttle valve.
•Delivery side is connected
to condenser.
•It is usually specified in
terms of liters.

16. Vapour Absorption Refrigeration
• In VAR refrigerant from evaporator is
absorbed in absorber.
• Ammonia is generally used as
refrigerant due to its property of being
absorbed easily by water at low
pressure and temperature, and at high
temperature its solubility in water is
reduced.
• So when heated it gets separated
from water.
• Water acts as an absorbent.

17. Vapour Absorption
refrigerationLow pressure T and P
vapour ammonia from
evaporator enters
absorber where it is
absorbed by weak
solution coming from
generator through
throttle valve.
During absorption
process, heat is
released and rejected to
cooling water. This
solution is pumped back
into generator, where it
is heated and h3
separates from water
and this water flows
back into absorber

18. Air refrigeration (Bell Coleman
Cycle)
 Process 1-2: Air from
cold storage enters air
compressor, due to
which its pressure and temperature
increases.
 Process 2–3: Hot air
is cooled and temp. is
reduced.

19. Air refrigeration (Bell Coleman
Cycle)
 Process 3-4: Air is
expanded isentropically,
as a result T and P
reduces and work is
obtained.
 Process 4-1: From
expander air passes
through cold storage
where heat is remove
and again cycle is
repeated.

20. P-V & T-S Diagrams

21. Advantages of Air
refrigeration
1. Free availability of air
2. Weight of air refrigerator per ton is
low, so this can be used in air crafts
and missiles cooling.

22. Disadvantages of Air
refrigeration
1. Very low COP
2. Large power requirement
3. More space
4. Volume of air to be circulated is more
compared to other refrigerators. This
sets the limitation of its usage to
small capacity plants.

23. Characteristic Comparison

24. Air Conditioning
 Air conditioning is simultaneous
control of temperature, air humidity, air
movement and air cleanliness.
Major Applications of AC:
A) For human comfort
B) For commercial use (industrial air
conditioning)

25. Comforting
 Temperature and humidity that is
soothing for human life is called
comforting of humans, and as listed
below:
1. DBT 17 to 25 degrees
2. RH 30 to 70%
3. 0.1 to 0.25m/s air velocity

26. Principle
 Air conditioning device draws air from
the space to be cooled, cools it down
and rejects back into the same cooling
space.
 Continuous circulation of air maintains
the required low temperature in the
room.

27. Components and functions of AC
unit
1. Fan: air circulation
2. Filters: cleanliness
3. Heating system: heat of air (Winter
AC)
4. Control System: automatic
temperature control
5. Grille: Direction of flow air
6. Tray: storage of condensed water.
7. Refrigerating plant: Cooling effect.

28. Classification
Arrangement Purpose
Unitary Central Comfort Industry
Arrangement
Winter
AC
Summer
AC

29. Window AC
 Two major units
1. Refrigeration Unit: evaporator,
condenser, compressor, expansion
valve
2. Air circulation fan

30. Window AC Working

31. SPLIT AC
 Window AC is split into two halves
1. Placed inside the room (Usually wall
mounted), includes evaporator, filter,
grille.
2. Placed outside the room and
includes condenser fan, compressor
and condenser.

32. SPLIT AC

33. Advantages of SPLIT AC over
Window AC
 No noise.
 No window space required.
 Aesthetic view.