Test: Heat Pump & Refrigeration Cycles & Systems - 1 - Mechanical Engineering MCQ

In the case of a refrigeration system undergoing an irreversible cycle,  is:

A heat pump is used to heat a house in the winter and then reversed to cool the house in the summer. The inside temperature of the house is to be maintained at 20°C. The heat transfer through the house walls is 7·9 kJ/s and the outside temperature in winter is 5°C. What is the minimum power (approximate) required driving the heat pump?

Assertion (A): If a domestic refrigerator works inside an adiabatic room with its door open, the room temperature gradually decreases.  

Reason (R): Vapour compression refrigeration cycles have high COP compared to air refrigeration cycles.

A building in a cold climate is to be heated by a Carnot heat pump. The minimum outside temperature is –23°C. If the building is to be kept at 27°C and heat requirement is at the rate of 30 kW, what is the minimum power required for heat pump?

A refrigerator working on a reversed Carnot cycle has a C.O.P. of 4. If it works as a heat pump and consumes 1 kW, the heating effect will be:

Round the clock cooling of an apartment having a load of 300 MJ/day requires an air-conditioning plant of capacity about

A refrigerator based on reversed Carnot cycle works between two such temperatures that the ratio between the low and high temperature is 0.8. If a heat pump is operated between same temperature range, then what would be its COP?

A heat pump operating on Carnot cycle pumps heat from a reservoir at 300 K to a reservoir at 600 K. The coefficient of performance is:  

The refrigerating efficiency that is the ratio of actual COP to reversible COP of a refrigeration cycle is 0.8, the condenser and evaporator temperatures are 50°C and –30°C respectively. If cooling capacity of the plant is 2.4 kW then what is the work requirement?

A Carnot heat pump works between temperature limits of 277º C and 27º C. Its COP is

Assertion (A ):Power input per TR of a refrigeration system increases with decrease in evaporator temperature.   

Reason (R): COP  of  refrigeration system decreases with decrease in evaporator temperature. 

A Carnot refrigerator requires 1.5 kW/ton of refrigeration to maintain a region at a temperature of – 30°C. The COP of the Carnot refrigerator is: 

The COP of a Carnot refrigeration cycle decreases on

The coefficient of performance of a refrigerator working on a reversed Carnot cycle is 4. The ratio of the highest absolute temperature to the lowest absolute temperature is:

Assertion (A): The coefficient of performance of a heat pump is greater than that for the refrigerating machine operating between the same temperature limits

Reason (R): The refrigerating machine requires more energy for working where as a heat pump requires less.

The power (kW) required per ton of refrigeration is  where COP is the coefficient of performance, then N is equal to:

The COP of refrigeration cycle is given by

(A) : none of the mentioned below ​
(B) : 1 / {(p1/p2)^ɣ/(ɣ-1)]} – 1
(C) : 1 / {(p1/p2)^(ɣ-1)/ɣ]} + 1
(D) : 1 / {(p1/p2)^(ɣ-1)/ɣ]} – 1 (A)