Which of the following is not the difference between theoretical and actual VCR cycle? Explanation: Entropy is the randomness of molecules. Change in entropy cannot be kept constant.

COP stands for Coefficient Of Performance and indicates the efficiency of heating and cooling machines. The COP is defined by the ratio heat dissipation and electrical power intake. It’s like the efficiency of the machine, but higher than 100%. It could be less than 100% for a machine not working properly.

A distinction is made between the theoretical COP and the actual COP of a refrigerating machine. The theoretical COP for all other refrigeration cycles does not exceed εc for machines operating under the same temperature conditions. The COP of a real refrigerating machine is always less than the theoretical COP.

Actual vapor compression cycle is different from theoretical vapor compression cycle. In actual vapor compression cycle condensation and evaporation do not occur at constant pressure. Further compression is not isentropic and the overall COP of the cycle is lower.

Therefore with decrease in suction pressure the net effect decreases the COP of the system for the same amount of refrigerant flow. The refrigerating capacity of system decreases and refrigeration cost increases.

Effect of Suction Pressure Since the C.O.P. of the system is the ratio of refrigerating effect to the work done, therefore with the decrease in suction pressure, the net effect is to decrease C.O.P. of the refrigerating system for the same amount of refrigerant flow.

Which one of the following is not an assumption in theoretical vapour compression cycle? Explanation: There are no mechanical or fluid friction losses, is one of the assumptions made in theoretical vapor compression cycle.

12. Which of the following is true for a multi-stage compression? Explanation: These are few advantages of multi-stage compression. Explanation: Multi-cylinders need smaller flywheel and give uniform torque.