Refrigeration and Air Conditioning

51. One of the purposes of sub-cooling the liquid refrigerant is to

  1. reduce compressor overheating
  2. reduce compressor discharge temperature
  3. increase cooling effect
  4. ensure that only liquid and not the vapour enters the expansion (throttling) valve
  5. none of the above.

Correct answer: (D)
ensure that only liquid and not the vapour enters the expansion (throttling) valve

52. One ton of refrigeration is equal to the refrigeration effect corresponding to melting of 1000 kg of ice

  1. in 1 hour
  2. in 1 minute
  3. in 24 hours
  4. in 12 hours
  5. in 10 hours.

Correct answer: (C)
in 24 hours

53. One ton of the refrigeration is

  1. the standard unit used in refrigeration problems
  2. the cooling effect produced by melting 1 ton of ice
  3. the refrigeration effect to freeze 1 ton of water at 0°C into ice at 0°C in 24 hours
  4. the refrigeration effect to produce 1 ton of ice at NTP conditions
  5. the refrigeration effect to produce 1 ton of ice in 1 hour time.

Correct answer: (C)
the refrigeration effect to freeze 1 ton of water at 0°C into ice at 0°C in 24 hours

54. One ton refrigeratiqn corresponds to

  1. 50 kcal/min
  2. 50 kcal/kr
  3. 80 kcal/min
  4. 80 kcal/hr
  5. 1000 kcal/day.

Correct answer: (A)
50 kcal/min

55. Pick up the correct statement about giving up of heat from one medium to other in ammonia absorption system

  1. strong solution to weak solution
  2. weak solution to strong solution
  3. strong solution to ammonia vapour
  4. ammonia vapour to weak solution
  5. ammonia vapour to strong solution.

Correct answer: (B)
weak solution to strong solution

56. Pick up the wrong statement. A refrigerant should have

  1. Tow specific heat of liquid
  2. high boiling point
  3. high latent heat of vaporisation
  4. higher critical temperature
  5. low specific volume of vapour.

Correct answer: (B)
high boiling point

57. Presence of moisture in a refrigerant affects the working of

  1. compressor
  2. condenser
  3. evaparator
  4. expansion valve.
  5. heat transfer.

Correct answer: (D)
expansion valve.

58. Rating of a domestic refrigerator is of the order of

  1. 0.1 ton
  2. 5 tons
  3. 10 tons
  4. 40 tons
  5. 100 tons.

Correct answer: (A)
0.1 ton

59. Reducing suction pressure in refrigeration cycle

  1. lowers evaporation temperature
  2. increases power required per ton of refrigeration
  3. lowers compressor capacity because vapour is lighter
  4. reduces weight displaced by piston
  5. all of the above.

Correct answer: (E)
all of the above.

60. Refrigeration in aeroplanes usually employs the following refrigerant

  1. Co2
  2. Freon-11
  3. Freon-22
  4. Air
  5. none of the above.

Correct answer: (D)
Air

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