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Mechanical Engineering :: Heat Transfer,Refrigeration and Air Conditioning

  1. The wet bulb temperature lines, on the psychrometric chart, are curved lines.

  2. A.
    True
    B.
    False

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  3. The sensible heat factor during cooling and dehumidification process is given by (where h1 = Enthalpy of air entering the cooling coil, h2 = Enthalpy of air leaving the cooling coil, and hA = Enthalpy of air at the end of dehumidification process)

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  5. Thermal diffusivity is a

  6. A.
    function of temperature
    B.
    physical property of a substance
    C.
    dimensionless parameter
    D.
    all of these

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  7. The condition of refrigerant after leaving the compressor and before entering the condenser is superheated vapour.

  8. A.
    Yes
    B.
    No

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  9. The total radiation from a black body per second per unit area is __________ fourth power of the absolute temperature. This statement is known as Stefan-Boltzmann law.

  10. A.
    equal to
    B.
    directly proportional to
    C.
    inversely proportional to

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  11. Which of the following represents a heat pump?

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  13. In a psychrometric process, the sensible heat added is 30 kJ/s and the latent heat added is 20 kJ/s. The sensible heat factor for the process will be

  14. A.
    0.3
    B.
    0.6
    C.
    0.67
    D.
    1.5

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  15. The amount of radiation mainly depends upon the

  16. A.
    nature of the body
    B.
    temperature of the body
    C.
    type of surface of the body
    D.
    all of these

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  17. For ammonia refrigerating systems, the tubes of a shell and tube condenser are made of

  18. A.
    copper
    B.
    aluminium
    C.
    steel
    D.
    brass

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  19. The highest thermal diffusivity is of

  20. A.
    iron
    B.
    lead
    C.
    concrete
    D.
    wood

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