Answer Happy

04 (a) 30 kW of heat is to be transferred from the cold compartment of an industrial refrigerator with the temperature of -10°C. The fridge is inside a room at 20°C and consumes 5.5 kW of electrical power. Answer the following questions: i Briefly explain the similarities and differences between the refrigeration and steam cycle for power generation. [4) ii. iii. If a fridge is put inside a room while the door of the fridge is kept fully open, what happens to the air temperature inside the room? Briefly, explain the heat transfer process in this case. [2] Calculate the coefficient of performance of this refrigerator? [3] Calculate the rate of heat transfer from the refrigerator to the room? [2] On a winter day, the temperature of the room reaches 3°C, while other quantities remain unchanged. Without showing any calculations, predict whether the coefficient of performance goes up, comes down or remains the same. Briefly explain your reasons. iv. vi. Briefly explain why it is impossible to run a refrigerator without any work (electricity) input [2] (b) A refrigeration unit is cooling a space to -5°C by rejecting energy to the atmosphere at 20°C. It is desired to reduce the temperature in the refrigerated space to -25°C. Calculate the minimum percentage increase in work required, by assuming a Carnot refrigerator, for the same amount of energy removed. [8]