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Mechanical Engineering :: Refrigeration and Air Conditioning

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

  2. A.

     (hA - h2)/ (h1 - h2)

    B.

     (h2 - hA)/ (h1 - h2)

    C.

     (h1 - h2)/ (hA - h2)

    D.

     (hA - h1)/ (h2 - h1)


  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)

  4. A.

     (hA - h2)/ (h1 - h2)

    B.

     (h2 - hA)/ (h1 - h2)

    C.

     (h1 - h2)/ (hA - h2)

    D.

     (hA - h1)/ (h2 - h1)


  5. In chemical dehumidification process,

  6. A.

     Dew point temperature decreases

    B.

     Wet bulb temperature decreases

    C.

     Dry bulb temperature increases

    D.

     All of these


  7. The specific humidity during heating and humidification process.

  8. A.

     Remains constant

    B.

     Increases

    C.

     Decreases

    D.

     None of these


  9. For evaporators and condensers, for the given conditions, the logarithmic mean temperature difference (tm) for parallel flow is ________ that for counter flow.

  10. A.

     Equal to

    B.

     Less than

    C.

     Greater than

    D.

     None of these


  11. 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

  12. A.

     Ammonia

    B.

     Carbon dioxide

    C.

     Freon

    D.

     Brine


  13. Reducing suction pressure in refrigeration cycle

  14. A.

     Lowers evaporation temperature

    B.

     Increases power required per ton of refrigeration

    C.

     Lowers compressor capacity because vapour is lighter

    D.

     All of the above


  15. The sub-cooling in a refrigeration cycle

  16. A.

     Does not alter C.O.P.

    B.

     Increases C.O.P.

    C.

     Decreases C.O.P.

    D.

     None of these


  17. The superheating in a refrigeration cycle

  18. A.

     Does not alter C.O.P.

    B.

     Increases C.O.P.

    C.

     Decreases C.O.P.

    D.

     None of these


  19. Under cooling in a refrigeration cycle

  20. A.

     Increases C.O.P

    B.

     Decreases C.O.P

    C.

     C.O.P remains unaltered

    D.

     Other factors decide C.O.P