Refrigeration and Air Conditioning

31. If a heat pump cycle operates between the condenser temperature of +27°C and evaporator temperature of - 23°C, then the Carnot COP will be

  1. 0.2
  2. 1.2
  3. 5
  4. 6
  5. 10

Correct answer: (D)
6

32. If the evaporator temperature of a plant is lowered, keeping the condenser temperature constant, the h.p. of compressor required will be

  1. same
  2. more
  3. less
  4. more/less depending on rating
  5. unpredictable.

Correct answer: (B)
more

33. In a flooded evaporator refrigerator, an accumulator at suction of compressor is used to

  1. collect liquid refrigerant and prevent it from going to compressor
  2. detect liquid in vapour
  3. superheat the vapour
  4. collect vapours
  5. increase refrigeration effect.

Correct answer: (A)
collect liquid refrigerant and prevent it from going to compressor

34. In a refrigeration cycle, the flow of refrigerant is controlled by

  1. compressor
  2. condenser
  3. evaporator
  4. expansion valve
  5. all of the above.

Correct answer: (D)
expansion valve

35. In a refrigeration system, heat absorbed in comparison to heat rejected is

  1. more
  2. less
  3. same
  4. more for small capacity and less for high capacity
  5. less for small capacity and more for high capacity.

Correct answer: (B)
less

36. In a vapour compression cycle, the refrigerant immediately after expansion valve is

  1. liquid
  2. sub-cooled liquid
  3. saturated liquid
  4. wet vapour
  5. dry vapour.

Correct answer: (D)
wet vapour

37. In refrigerator, liquid receiver is required between condenser and flow controlling device, if quantity of refrigerant for system is

  1. less than 2 kg
  2. more than or equal to 3.65 kg
  3. more than 10 kg
  4. there is no such consideration
  5. pone of the above.

Correct answer: (B)
more than or equal to 3.65 kg

38. In refrigerators, the temperature difference between the evaporating refrigerant and the medium being cooled should be

  1. high, of the order of 25°
  2. as low as possible (3 to 11°C)
  3. zero
  4. any value
  5. none of the above.

Correct answer: (B)
as low as possible (3 to 11°C)

39. In S.J. unit, one ton of refrigeration is equal to

  1. 210 kJ/min
  2. 21 kJ/min
  3. 420 kJ/min
  4. 840 kJ/min
  5. 105 kJ/min.

Correct answer: (A)
210 kJ/min

40. In vapour compression cycle the condition of refrigerant is superheated vapour

  1. after passing through the condenser
  2. before passing through the condenser
  3. after passing through the expansion or throttle valve
  4. before [entering the expansion valve
  5. before entering the compressor.

Correct answer: (B)
before passing through the condenser

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