Refrigeration and air conditioning objective type questions and answers - Set 16 - ObjectiveBooks

# Practice Test: Question Set - 16

1. For evaporators and condensers, for the given conditions, the logarithmic mean temperature difference (tm) for parallel flow is ________ that for counter flow.
(A) Equal to
(B) Less than
(C) Greater than
(D) None of these

2. A vapour absorption refrigerator uses _________ as a refrigerant.
(A) Water
(B) Ammonia
(C) Freon
(D) Aqua-ammonia

3. Bell Coleman cycle is a
(A) Reversed Carnot cycle
(B) Reversed Otto cycle
(C) Reversed Joule cycle
(D) Reversed Rankine cycle

4. The coefficient of performance of Electrolux refrigerator is the ratio of
(A) Heat supplied by the gas burner to the heat absorbed by the evaporator
(B) Heat absorbed by the evaporator to the heat supplied by the gas burner
(C) Heat supplied by the gas burner minus the heat absorbed by the evaporator to the heat supplied by the gas burner
(D) Heat absorbed by the evaporator minus the heat supplied by the gas burner to the heat absorbed by the evaporator

5. Which of the following refrigerant has the lowest freezing point?
(A) R-11
(B) R-12
(C) R-22
(D) Ammonia

6. In Electrolux refrigerator
(A) Ammonia is absorbed in hydrogen
(B) Ammonia is absorbed in water
(C) Ammonia evaporates in hydrogen
(D) Hydrogen evaporates in ammonia

7. One tonne of refrigeration (1TR) means that the heat removing capacity is
(A) 21 kJ/min
(B) 210 kJ/min
(C) 420 kJ/min
(D) 620 kJ/min

8. The superheated vapour region, in a pressure enthalpy chart, is represented by the space
(A) To the left of saturated liquid line
(B) To the right of saturated liquid line
(C) Between the saturated liquid line and saturated vapour line
(D) None of the above

9. A good refrigerant should have
(A) High latent heat of vaporisation and low freezing point
(B) High operating pressures and low freezing point
(C) High specific volume and high latent heat of vaporisation
(D) Low C.O.P. and low freezing point

10. Air refrigeration cycle is used in
(A) Commercial refrigerators
(B) Domestic refrigerators
(C) Air-conditioning
(D) Gas liquefaction

11. In a saturated air-water vapour mixture, the
(A) Dry bulb temperature is higher than wet bulb temperature
(B) Dew point temperature is lower than wet bulb temperature
(C) Dry bulb, wet bulb and dew point temperature are same
(D) Dry bulb temperature is higher than dew point temperature

12. The capillary tube is not used in large capacity refrigeration systems because
(A) Cost is too high
(B) Capacity control is not possible
(C) It is made of copper
(D) Required pressure drop cannot be achieved

13. The thermostatic expansion valve operates on the changes in the
(A) Degree of superheat at exit from the evaporator
(B) Temperature of the evaporator
(C) Pressure in the evaporator
(D) None of the above

14. In a vapour compression system, the condition of refrigerant before entering the expansion or throttle valve is
(A) High pressure saturated liquid
(B) Wet vapour
(C) Very wet vapour
(D) Dry vapour

15. The freezing point of R-12 is
(A) -86.6°C
(B) -95.2°C
(C) -107.7°C
(D) -135.8°C

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