k10998 (wasique ahmad )rac

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 RefrigerationRefrigerantVapour compression cycleEffect CopMerit DemeritAdvantageBy 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.

RefrigerantRefrigerant 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.InflammabilityLeakageToxicity

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 refrigerantThat’s why R-134 is a eco-friendly in nature .

ConclusionAt finally we conclude that v c cycle is work on high grade

energy and it is where used there is small spaceIt is used for making environment cool