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Mechanical Engineering :: Refrigeration and Air Conditioning

  1. During cooling and dehumidification, dry bulb temperature

  2. A.

     Remains constant

    B.

     Increases

    C.

     Decreases

    D.

     None of these

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  3. In a domestic vapour compression refrigerator, the refrigerant commonly used is

  4. A.

     CO?

    B.

     Ammonia

    C.

     R-12

    D.

     All of these

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

  6. A.

     High, of the order of 25°

    B.

     As low as possible (3 to 11°C)

    C.

     Zero

    D.

     Any value

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  7. The minimum temperature to which water can be cooled in a cooling tower is

  8. A.

     Dew point temperature of air

    B.

     Wet bulb temperature of air

    C.

     Dry bulb temperature of air

    D.

     Ambient air temperature

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  9. Air refrigeration cycle is used in

  10. A.

     Domestic refrigerators

    B.

     Commercial refrigerators

    C.

     Air conditioning

    D.

     Gas liquefaction

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  11. The value of C.O.P in vapour compression cycle is usually

  12. A.

     Always less than unity

    B.

     Always more than unity

    C.

     Equal to unity

    D.

     Any one of the above

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  13. The specific humidity during cooling and dehumidification

  14. A.

     Remains constant

    B.

     Increases

    C.

     Decreases

    D.

     None of these

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  15. The suction pipe diameter of refrigerating unit compressor in comparison to delivery side is

  16. A.

     Bigger

    B.

     Smaller

    C.

     Equal

    D.

     Smaller/bigger depending on capacity

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  17. In a vapour compression refrigeration system, a throttle valve is used in place of an expander because

  18. A.

     It considerably reduces mass of the system

    B.

     It improves the C.O.P., as the condenser is small

    C.

     The positive work in isentropic expansion of liquid is very small

    D.

     It leads to significant cost reduction

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

  20. A.

     More

    B.

     Less

    C.

     Same

    D.

     More for small capacity and less for high capacity

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