rac k10998 ppt
TRANSCRIPT
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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
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Table of Content
• Refrigeration• Refrigerant• Vapour compression cycle• Effect • Cop• Merit • Demerit• Advantage• By studying of research paper
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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.
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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.
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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.
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Fig:- The P-h diagram is another convenient diagram often used to illustrate the refrigeration
cycle.
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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
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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)
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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
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EffectReduction in Refrigeration effectsIncrease in work inputDecrease in COPDecrease in volumetric efficiency due to increase in pressure
ratio.
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RE= h1-h4
Win=h2-h1
COP= RE/Win
• Case 2:- Increase in condenser pressure
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Effect Reduction in Refrigeration effectsIncrease in work inputDecrease in COPDecrease in volumetric efficiency due to increase in pressure
ratio.
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RE= h1-h4
Win=COP= RE/Win
• Case 3:- Superheating
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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.
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MERIT
• Cop is high.• Size of evaporator is small.• Evaporator temperature adjustment is small.• Easily available .• It is used for small places like shops.
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Demerit
• Initial cost is high.• Inflammability• Leakage• Toxicity
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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).
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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 .
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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
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