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Mechanical Engineering :: Heat Transfer,Refrigeration and Air Conditioning

  1. The ratio of actual mass of water vapour in a given volume of moist air to the mass of water vapour in the same volume of saturated air at the same temperature and pressure, is called

  2. A.
    humidity ratio
    B.
    relative humidity
    C.
    absolute humidity
    D.
    degree of saturation

  3. The transfer of heat by molecular collision is smallest in

  4. A.
    solids
    B.
    liquids
    C.
    gases
    D.
    none of these

  5. During dehumidification process, the relative humidity

  6. A.
    remains constant
    B.
    increases
    C.
    decreases

  7. The space between the two walls of a thermos flask is evacuated because vacuum is a __________ conductor of heat.

  8. A.
    good
    B.
    bad

  9. The ratio of actual heat transfer to the maximum possible heat transfer is known as heat exchanger effectiveness.

  10. A.
    Agree
    B.
    Disagree

  11. When the discharge pressure is too high in a refrigeration system, high pressure control is installed to stop the compressor.

  12. A.
    Correct
    B.
    Incorrect

  13. A grey body is one whose absorptivity does not vary with temperature and wave length of the incident ray.

  14. A.
    True
    B.
    False

  15. The wet bulb temperature during sensible cooling of air

  16. A.
    remains constant
    B.
    increases
    C.
    decreases

  17. In absorption vapour systems, the refrigerant widely used is R-12.

  18. A.
    Correct
    B.
    Incorrect

  19. Hydrogen is used in electrolux refrigeration system so as to __________ the rate of evaporation of the liquid ammonia passing through the evaporator.

  20. A.
    equalise
    B.
    reduce
    C.
    increase