Multiple Choice Questions on Refrigeration and Air-Conditioning - Set 08

Practice Test: Question Set - 08

1. The value of C.O.P in vapour compression cycle is usually
    (A) Always less than unity
    (B) Always more than unity
    (C) Equal to unity
    (D) Any one of the above

2. The C.O.P. of a refrigerator working on a reversed Carnot cycle is (where T₁ = Lowest absolute temperature, and T₂ = Highest absolute temperature)
    (A) T₁ / (T₂ - T₁)
    (B) (T₂ - T₁)/T₁
    (C) (T₁ - T₂)/T₁
    (D) T₂/ (T₂ - T₁)

3. Which of the following is not a desirable property of a refrigerant?
    (A) High risibility with oil
    (B) Low boiling point
    (C) Good electrical conductor
    (D) Large latent heat

4. The refrigerant after condensation process is cooled below the saturation temperature before throttling. Such a process is called
    (A) Sub-cooling or under-cooling
    (B) Super-cooling
    (C) Normal cooling
    (D) None of these

5. A certain refrigerating system has a normal operating suction pressure of 10 kg/cm gauge and condensing pressure of about 67 kg/cm. The refrigerant used is
    (A) Ammonia
    (B) Carbon dioxide
    (C) Freon
    (D) Brine

6. The capillary tube, as an expansion device, is used in
    (A) Domestic refrigerators
    (B) Water coolers
    (C) Room air conditioners
    (D) All of these

7. 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
    (A) 0.2
    (B) 1.2
    (C) 5
    (D) 6

8. Which of the following statement is correct?
    (A) The human body can lose heat even if its temperature is less than the atmospheric temperature.
    (B) The increase in air movement increases the evaporation from the human body.
    (C) The warm air increases the rate of radiation of heat from the human body.
    (D) Both (A) and (B)

9. In a flooded evaporator refrigerator, an accumulator at suction of compressor is used to
    (A) Collect liquid refrigerant and prevent it from going to compressor
    (B) Detect liquid in vapour
    (C) Superheat the vapour
    (D) Collect vapours

10. The minimum temperature to which water can be cooled in a cooling tower is
    (A) Dew point temperature of air
    (B) Wet bulb temperature of air
    (C) Dry bulb temperature of air
    (D) Ambient air temperature

11. Highest temperature encountered in refrigeration cycle should be
    (A) Near critical temperature of refrigerant
    (B) Above critical temperature
    (C) At critical Temperature
    (D) Much below critical temperature

12. The operating pressure for refrigerating units using R-12 as a refrigerant is
    (A) 2 bar
    (B) 8 bar
    (C) 15 bar
    (D) 30 bar

13. The domestic refrigerator uses following type of compressor
    (A) Centrifugal
    (B) Axial
    (C) Miniature sealed unit
    (D) Piston type reciprocating

14. A bootstrap air cooling system has
    (A) One heat exchanger
    (B) Two heat exchangers
    (C) Three heat exchangers
    (D) Four heat exchangers

15. Critical temperature is the temperature above which
    (A) A gas will never liquefy
    (B) A gas will immediately liquefy
    (C) Water will evaporate
    (D) Water will never evaporate

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