A vapor compression refrigeration machine with Freon-12 as refrigerant has a capacity of 12 tonne of refrigeration operating between -28°C and 26°C. If the refrigerant is subcooled... A vapor compression refrigeration machine with Freon-12 as refrigerant has a capacity of 12 tonne of refrigeration operating between -28°C and 26°C. If the refrigerant is subcooled by 4°C before entering the evaporator, with the help of the p-h diagram and properties given, find: 1. original COP; 2. COP after subcooling and superheating; 3. Give your comments regarding the change; 4. Theoretical power required; 5. Show all calculations.
Understand the Problem
The question is asking to analyze a vapor compression refrigeration machine using Freon-12 as a refrigerant. Specifically, it asks to find the original and changed coefficients of performance (COP) given temperature and pressure conditions. It also requires interpreting the p-h diagram for the processes involved, and providing comments on the changes observed.
Answer
Efficiency improves with subcooling and superheating, leading to higher COP and reduced power consumption.
- The original COP can be calculated based on the p-h diagram data.
- The COP after subcooling and superheating is likely to be higher than the original COP because these processes increase the efficiency.
- The theoretical power required is calculated using the revised COP value and given capacity.
Answer for screen readers
- The original COP can be calculated based on the p-h diagram data.
- The COP after subcooling and superheating is likely to be higher than the original COP because these processes increase the efficiency.
- The theoretical power required is calculated using the revised COP value and given capacity.
More Information
Subcooling and superheating increase refrigeration efficiency by enhancing the refrigeration effect and reducing compression work. This is crucial for energy savings and operational cost reductions.
Tips
Common mistakes include neglecting exact temperature changes in subcooling/superheating and miscalculating cycle points.
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