rac k10998 ppt

CAREER POINT UNIVE

SUBMITTED BY-Wasique AhmadUID –K10998B.TECH 3RD YEARBRANCH-MECHANICAL

SUBMITTED TO-MR. ADITYA MISHRA

ASS.PROF.OF ME DEPT.

MAJOR ASSIGNMENTVapours Compression Refrigeration Cycle

Table of Content

• Refrigeration• Refrigerant• Vapour compression cycle• Effect • Cop• Merit • Demerit• Advantage• By studying of research paper

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.

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.

V c cycle

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.

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

cycle.

COP Of V.C. CycleApply Steady flow energy equation ( Neglect K.E & P.E changes)1. Compressor: Q1-2 + C1

2/2 + Z 1 + h1 = W1-2 + C22/2 + Z 2+ h2

W1-2 = - ( h2 – h1)2. Condenser:Q2-3 + C2

2/2 + Z 2 + h2 = W2-3 + C32/2 + Z 3+ h3

Q2-3 = - (h2 - h3)3. Throttle Valve:Q3-4 + C3

2/2 + Z 3 + h3 = W3-4 + C42/2 + Z 4+ h4

h3 = h4 (Isenthalpic process)

4. Evaporator:Q4-1 + C4

2/2 + Z 4 + h4 = W4-1 + C12/2 + Z 1+ h1

Q4-1 + h4 = h1

Q4-1 = h1 – h4

COP

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)

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

EffectReduction in Refrigeration effectsIncrease in work inputDecrease in COPDecrease in volumetric efficiency due to increase in pressure

ratio.

RE= h1-h4

Win=h2-h1

COP= RE/Win

• Case 2:- Increase in condenser pressure

Effect Reduction in Refrigeration effectsIncrease in work inputDecrease in COPDecrease in volumetric efficiency due to increase in pressure

ratio.

RE= h1-h4

Win=COP= RE/Win

• Case 3:- Superheating

Effect Increase in Refrigeration effectIncrease 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.

MERIT

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

Demerit

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

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).

Studying by research paper

• By getting result of R134a is a best refrigerant among all refrigerant.

• Because COP is lower as compare to other refrigerant• That’s why R-134 is a eco-friendly in nature .

Conclusion

• At finally we conclude that v c cycle is work on high grade energy and it is where used there is small space

• It is used for making environment cool