Test: Heat Pump & Refrigeration Cycles & Systems - 2 - Mechanical Engineering MCQ

In a refrigeration plant, if the condenser temperature increases, the power input to the compressor will  

The COP of a Carnot heat pump used for heating a room at 20°C by exchanging heat with river water at 10°C is:

A refrigerating machine working on reversed Carnot cycle consumes 6kW to produce a refrigerating effect of 1000kJ/min for maintaining a region at – 40oC.The higher temperature (in degree centigrade) of the cycle will be: 

A Carnot refrigerator works between the temperatures of 200 K and 300 K. If the refrigerator receives 1 kW of heat the work requirement will be: 

Operating temperature of a cold storage is –2°C From the surrounding at ambient temperature of 40°C heat leaked into the cold storage is 30 kW. If the actual COP of the plant is 1/10th of the maximum possible COP, then what will be the power required to pump out the heat to maintain the cold storage temperature at –2°C?

One ton refrigeration is equivalent to:

When the lower temperature is fixed, COP of a refrigerating machine can be improved by:

A refrigerating machine working on reversed Carnot cycle takes out 2 kW of heat from the system at 200 K while working between temperature limits of 300 K and 200 K. COP and power consumed by the cycle will, respectively, be:

In the system given above, the temperature T = 300 K. When is the thermodynamic efficiency σE of engine E equal to the reciprocal of the COP of R? 

The COP of a Carnot heat pump used for heating a room at 20°C by exchanging heat with river water at 10°C is:

A refrigeration system operates on the reversed Carnot cycle. The temperature for the system is: Higher temperature = 40°C and Lower temperature = 20°C.

The capacity of the refrigeration system is 10 TR. What is the heat rejected from the system per hour if all the losses are neglected? 

Assertion (A ): T he COP of an air-conditioning plant is lower than that of an ice plant. 

Reason (R): The  tem peratures required in the ice plant are lower than those required for an air-conditioning plant. 

For a given value of T_H (Source temperature) for a reversed Carnot cycle, the variation of T_L (Sink temperature) for different values of COP is represented by which one of the following graphs?

Efficiency of a Carnot engine is 75%. If the cycle direction is reversed, COP of the reversed Carnot cycle is  

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

A refrigerator works on reversed Carnot cycle producing a temperature of – 40°C. Work done per TR is 700 kJ per ten minutes. What is the value of its COP? 

In the above figure, E is a heat engine with efficiency of 0.4 and R is a refrigerator. Given that Q₂ + Q₄ = 3Q₁ the COP of the refrigerator is:

The coefficient of performance (COP) of a refrigerator working as a heat pump is given by:

A refrigerator operates between the temperatures of –23ºC and 27ºC. If one TR = 3.5 kW, the minimum power required per TR to operate the refrigerator is 

Which one of the following statements is correct?

In a domestic refrigerator periodic defrosting is required because frosting 

Consider the following statements:  In the thermoelectric refrigeration, the coefficient of performance is a function of: 

1. Electrical conductivity of materials  

2. Pelti er coefficie nt  

3. Seeb eck coefficie nt  

4. Temperature at cold and hot junctions  

5. Thermal conductivity of materials. 

Of these statements: 

[IES-1997]

In a reversible cycle, the source temperature is 227°C and the sink temperature is 27°C. The maximum available work for a heat input of 100 kJ will be:

In a 0.5 TR capacity water cooler, water enters at 30°C and leaves at 15°C.What is the actual water flow rate?

It is proposed to build refrigeration plant for a cold storage to be maintained at – 3°C. The ambient temperature is 27°C. If 5 × 106 kJ/h of energy is to be continuously removed from the cold storage, the MINIMUM power required to run the refrigerator will be:

Assertion (A ): When solid CO₂ (dry ice) is exposed to the atmosphere, it gets transformed directly into vapour absorbing the latent heat of sublimation from the surroundings

Reason (R): The triple  point of CO₂ is at about 5 atmospheric pressure and at 216 K. 

In a one ton capacity water cooler, water enters at 30°C at the rate of 200 litres per hour. The outlet temperature of water will be (sp. heat of water = 4.18 kJ/kg K)

A heat pump is shown schematically as