HEAT AND MASS TRANSFER MCQ

 

SECTION-3

 
Q31. Choose the correct statement

(a) The co-efficient of performance is always less than one. 
(b) The horse power per ton of refrigeration is 4.75 × (C.O.P.). 
(c) In S.I. units, one tonne of refrigeration is equal to 210 kJ/min. 
(d) In a refrigerating machine heat rejected is less than heat absorbed. 

Ans:(c) In S.I. units, one tonne of refrigeration is equal to 210 kJ/min.
 

 

Q32 The cycle, on which air refrigerator works, is

(a) Rankine cycle 
(b) Bell-Coleman cycle 
(C) Reversed Carnot cycle 
(D) both (b) and (C).

Ans:(D) both (b) and (C).
 

 

Q33. Which of the following is used as working fluid vapour in vapour compression refrigerator?

(a) carbon dioxide 
(b) ammonia 
(c) Freon-12 
(d) all of the above 

Ans:(d) all of the above
 

 

Q34. The function of oil separator in vapour compression refrigerator is to

(a) lubricate the compressor 
(b) reduce the heat transfer efficiency 
(c) prevent the oil being carried to condenser 
(d) none of the above.

Ans:(c) prevent the oil being carried to condenser
 

 

Q35. The coefficient of performance in wet compression as compared to dry compression is

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

Ans:(b) higher
 

 

Q36. In actual practice, dry compression is preferred as in dry compression

(a) there is higher volumetric efficiency 
(b) there is higher mechanical efficiency 
(c) there is less chances of damage of the compressor 
(D) all of the above 

Ans:(D) all of the above
 

 

Q37. Undercooling in a refrigeration cycle

(a) decreases the net refrigerating effect 
(b) increases the net refrigerating effect 
(c) has no effect on net refrigerating effect 
(d) first increases then decreases the net refrigerating effect.

Ans:(b) increases the net refrigerating effect
 

 

Q38. The refrigerant number R-744 means

(a) carbon dioxide 
(b) ammonia 
(c) sulphur dioxide 
(d) methyl chloride.

Ans:(a) carbon dioxide
 

 

Q39. If in question 107, the capacity of the refrigerator is 8 tons, the work done on the refrigerant per hour will be

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

Ans:(b) 4000 kcal/hr
 

 

Q40. The C.O.P. of a refrigerating machine, when lower temperature is fixed, can be improved by

(a) raising the higher temperature 
(b) lowering the higher temperature 
(c) keeping higher temperature constant 
(d) first increasing then decreasing.

Ans:(b) lowering the higher temperature
 
 
 

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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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