HEAT AND MASS TRANSFER MCQ

 

SECTION-3

Q41. The coefficient of performance of a vapour compression refrigerating cycle using expansion cylinder instead of throttle valve is

(a) higher 
(b) lower 
(c) same 
(d) none of the above.

Ans:(a) higher
 

 

Q42. Undercooling is the process of cooling the refrigerant

(a) after compression 
(b) before compression 
(c) after condensation before throttling 
(d) none of the above.

Ans:(c) after condensation before throttling
 

 

Q43. The C.O.P. of a refrigerating machine, when higher temperature is fixed, can be improved by

(a) raising the lower temperature 
(b) lowering the lower temperature 
(c) keeping the lower temperature constant 
(d) none of the above. 

Ans:(a) raising the lower temperature
 

 

Q44. The refrigerating effect means

(a) the heat rejected from the system per hour 
(b) the work done on the system 
(c) heat absorbed in the cycle from the body or space to be cooled 
(d) none of the above. 

Ans:(c) heat absorbed in the cycle from the body or space to be cooled
 

 

Q45. One tonne refrigeration in S.I. units is equivalent to

(a) 50 kJ/min 
(b) 3.5 kW 
(c) 3000 J/min 
(d) 200 kJ/min.

Ans:(b) 3.5 kW
  

 

Q46. The C.O.P. of a refrigerator working on a reversed Carnot cycle using perfect gas is equal to

(a) (1 – rγ−1
(b) 1/(rγ−11 −1)
(c) 1/ rγ−1
(d) 1/1+rγ−1
where r = Volume ratio for isentropic compression or expansion.

Ans:(c) 1/ rγ−1
 

 

Q47. The capacity of a refrigerator is one tonne. This means that the heat removing capacity (or refrigeration effect) of the refrigerator is

(a) 1000 kcal/hr 
(b) 2000 kcal/hr 
(c) 3000 kcal/hr 
(d) 4000 kcal/hr. 

Ans:(c) 3000 kcal/hr
 

 

Q48. The highest and lowest temperatures of the refrigerant in a refrigeration system which operates on the reversed Carnot cycle, at 27°C and –33°C respectively. The C.O.P. of the cycle is equal to

(a) 3.0 
(b) 2.0 
(c) 6.0 
(d) 1.5.

Ans:(c) 6.0
 

 

Q49. A refrigerating machine

(a) removes heat from a high temperature region to transfer it to a low temperature region 
(b) rejects energy to a low temperature region 
(c) removes heat from a low temperature region to transfer it to a high temperature region 
(d) none of the above. 

Ans:(c) removes heat from a low temperature region to transfer it to a high temperature region
 

 

Q50. The coefficient of performance (C.O.P.) is defined as

(a) (Work done on the system)/(Heat absorbed from the system) 
(b) (Heat absorbed from system)/(Work done on the system) 
(c) (Heat absorbed—Work done)/(Work done on the system) 
(d) (Work done on the system)/(Heat absorbed—-Work done).

Ans:(b) (Heat absorbed from system)/(Work done on the system)
 

 

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Read More Sections of Heat Transfer and Mass Transfer

Each section contains maximum 80 Questions. To practice more questions visit other sections.
 

Heat and Mass Transfer, RAC  MCQ – Section-1

 
Heat and Mass Transfer, RAC  MCQ – Section-2

 
Heat and Mass Transfer, RAC  MCQ – Section-3

 

Heat and Mass Transfer, RAC  MCQ – Section-4

 


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