QUESTION
Objective Question
The process of under-cooling is generally brought about by
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Answer
( Option D)
any one of the above
Solution
Process of VCRS:
Process 1-2: lsentropic compression of saturated vapour in compressor
Process 2-3': Isobaric heat rejection in condenser
Process 3'-3: Sub-cooling (Under cooling)
- Sometimes, the refrigerant,after the condensation process 2-3', is cooled below the saturation temperature (T3') before expansion by throttling.
- Such a process is called under-cooling or sub-cooling of the refrigerant.
- The refrigeration effect ls Increased due to sub-cooling.
- The ultimate effect of the under-cooling is to increase the value of the coefficient of performance under the same set of conditions.
- The process of under-cooling is generally brought about by circulating more quantity of cooling water through the condenser or by using water colder than the main circulating water.
- Sometimes, this process is also brought about by employing a heat exchanger.
- The magnitude of sub-cooling is usually kept between 5 to 10 K.
Process 3-4: lsenthalpic expansion of saturated liquid in throttling device
Process 4-1: Isobaric heat extraction in the evaporator.
