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Mechanical Engineering :: Heat Transfer,Refrigeration and Air Conditioning

  1. In a shell and coil condenser, water flows in the shell and the refrigerant in the coil.

  2. A.
    True
    B.
    False

  3. In a saturated air-water vapour mixture, the

  4. 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

  5. Dew point temperature corresponds to the saturation temperature of vapour at its partial pressure.

  6. A.
    True
    B.
    False

  7. The capillary tube is not used in large capacity refrigeration systems because

  8. A.
    cost is too high
    B.
    capacity control is not possible
    C.
    it is made of copper
    D.
    required pressure drop can not be achieved

  9. The ratio of emissive power of a body to the emissive power of a perfectly black body is called emissivity.

  10. A.
    Agree
    B.
    Disagree

  11. The thermostatic expansion valve operates on the changes in the

  12. A.
    degree of superheat at exit from the evaporator
    B.
    temperature of the evaporator
    C.
    pressure in the evaporator
    D.
    none of the above

  13. In a vapour compression system, the condition of refrigerant before entering the expansion or throttle valve is

  14. A.
    high pressure saturated liquid
    B.
    wet vapour
    C.
    very wet vapour
    D.
    dry vapour

  15. The freezing point of R-12 is

  16. A.
    -86.6°C
    B.
    -95.2°C
    C.
    -107.7°C
    D.
    -135.8°C

  17. The refrigerant supplied to a compressor must be

  18. A.
    superheated vapour refrigerant
    B.
    dry saturated liquid refrigerant
    C.
    a mixture of liquid and vapour refrigerant
    D.
    none of these

  19. The unit of thermal diffusivity is

  20. A.
    m/hK
    B.
    m/h
    C.
    m2/h
    D.
    m2/hK