The document discusses the vapor compression refrigeration cycle. It contains sections on refrigeration, refrigerants, the four main components of the vapor compression cycle (compressor, condenser, expansion valve, evaporator), coefficient of performance calculations, effects of varying operating parameters, advantages/disadvantages, and applications. The vapor compression cycle uses a refrigerant that is compressed to a high pressure and temperature gas, condensed to a high pressure liquid, expanded to a low pressure liquid, and evaporated to absorb heat before repeating the cycle.

1. MAJOR ASSIGNMENT
VAPOUR COMPRESSION REFRIGERATION CYCLE

2. Table of Content
• Refrigeration
• Refrigerant
• Vapour compression cycle
• Effect
• Cop
• Merit
• Demerit
• Advantage
• Application
• References

3. Introduction
• It is a heat operated system.
• It is quite similar to Vapour Compression systems. Condensation and
evaporation takes place at two different pressure levels to achieve
refrigeration.
• The main motive is to raise the temperature of the refrigerant from
evaporator pressure to condenser pressure.
• Here refrigerant is dissolved in inert liquid in absorber and pumped to
condenser.
• After raising pressure of refrigerant it is separated from solution by heating.
• After condensation in condenser, refrigerant is throttled by expansion valve
and then it evaporates in evaporator providing the refrigeration effect.

4. Refrigeration
• Refrigeration is the process of producing of lower temperature
compare to the surrounding temperature to maintain the
lower temperature.
• For example : vapour compression cycle, vapour absorption
cycle, gas refrigeration cycle.

5. Refrigerant
• Refrigerant are the substance which are used for producing
lower temperature .for example ammonia,water,air,R-12,R-
22,R-134.
Refrigeration effect: It is the amount of heat which is to be
extracted from the storage space in order to maintain lower
temperature is called desire effect of refrigeration system.

6. Vapour compression Refrigeration System:
There are four component in Vapour compression cycle.
1. Compressor:- Compresses the refrigerant to high pressure and temperature
from low pressure and temperature.
2. Condenser:- The latent heat of refrigerant is removed by circulating water or
atmospheric air.
3. Expansion Valve:- In the throttle valve where the pressure is reduced at a
controlled rate.
4. Evaporator:- A liquid-Vapour mixture refrigerant then enters the evaporator
at low pressure where the latent heat of evaporation is converted into vapour and
the cycle repeats.

7. Fig:- The P-h diagram is another convenient
diagram often used to illustrate the refrigeration
cycle.

8. Determination of COP:
Assumptions made for drawing T-S and P-h Diagram:
1. The refrigerant leaving the evaporator is dry and saturated.
2. The compression of vapour in the evaporator is isentropic.
3. There is no sub cooling of the refrigerant in the condenser.
4. There is no pressure losses in the system.
Conditions of vapour at the end of compression:
There are three different conditions at which the refrigerant from the compressor.
a. Vapour is dry and saturated.
b. Vapour is wet condition.
c. Vapour is superheated condition.

9. COP Of V.C. Cycle
Apply Steady flow energy equation ( Neglect K.E & P.E changes)
1. Compressor:
Q1-2 + C1
2/2 + Z 1 + h1 = W1-2 + C2
2/2 + Z 2+ h2
W1-2 = - ( h2 – h1)
2. Condenser:
Q2-3 + C2
2/2 + Z 2 + h2 = W2-3 + C3
2/2 + Z 3+ h3
Q2-3 = - (h2 - h3)
3. Throttle Valve:
Q3-4 + C3
2/2 + Z 3 + h3 = W3-4 + C4
2/2 + Z 4+ h4
h3 = h4 (Isenthalpic process)
4. Evaporator:
Q4-1 + C4
2/2 + Z 4 + h4 = W4-1 + C1
2/2 + Z 1+ h1
Q4-1 + h4 = h1
Q4-1 = h1 – h4

10. Co-efficient of Performance: It is the ratio of net refrigerating effect to the work
required to produce that effect.
Co-efficient of performance = Refrigerating effect/ Work input
= ( h1 – h4 ) / (h2 – h1)

11. Effects of variation of properties on the performance
of Vapour compression cycle:
Case 1:- Decrease in Evaporator:
RE= h1-h4
Win=h2-h1
COP= RE/Win

12. Effect
Reduction in Refrigeration effects
Increase in work input
Decrease in COP
Decrease in volumetric efficiency due to increase in pressure
ratio.

13. RE= h1-h4
Win=h2-h1
COP= RE/Win
• Case 2:- Increase in condenser pressure

14. Effect
Reduction in Refrigeration effects
Increase in work input
Decrease in COP
Decrease in volumetric efficiency due to increase in pressure
ratio.

15. RE= h1-h4
Win=
COP= RE/Win
• Case 3:- Superheating

16. Effect
Increase in Refrigeration effect
Increase in work input due to temperature at the inlet to
compressor increase.
COP may increase or decrease depending on the refrigerant. In
case of R- 12 superheating result in increase in COP where as in
case of NH3 superheating results in decrease in COP.

17. MERIT
• Cop is high.
• Size of evaporator is small.
• Evaporator temperature adjustment is small.
• Easily available .
• It is used for small places like shops.

18. Demerit
• Initial cost is high.
• Inflammability
• Leakage
• Toxicity

19. Advantages
• Lot of heat can be removed (lot of thermal energy to change
liquid to vapors).
• heat transfer rate become high(temperature of working fluid
much lower than what is being cooled).

20. Application
• 1. Ice making.
• 2. Transportation of food items above and below freezing.
• 2. Industrial Air – Conditioning.
• 4. Comfort Air – Conditioning.
• 5. Chemical and related industries.
• 6. Medical and Surgical instruments.
• 7. Processing food products and beverages.
• 8. Oil Refining.
• 9. Synthetic Rubber Manufacturing.
• 10. Manufacture and treatment of metals.
• 11. Freezing food products.
• 12. Manufacturing Solid Carbon Dioxide.
• 13. Production of extremely low temperatures (Cryogenics)
• 14. Plumbing.
• 15. Building Construction.

21. References
• Er. R.K. Rajput.Vapour compression Refrigeration Systems. Feb
03, 2014, “A textbook of Refrigeration & Air-conditioning-
2013”.
• Prof. M. Ramgopal. Various energy transfers in VARS (image).
Feb 02, 2014, from http://nptel.ac.in/courses/Webcourse-
contents/IIT%20Kharagpur/
• Prof. R. C. Arora. Domestic Electrolux Refrigerator (image). Feb
02, 2014, from http://nptel.ac.in/courses/Webcourse-
contents/IIT%20Kharagpur/Ref%20and%20Air%20Cond/pdf.