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Mechanical Engineering :: Refrigeration and Air Conditioning

  1. The optimum effective temperature for human comfort is

  2. A.

     Higher in winter than in summer

    B.

     Lower in winter than in summer

    C.

     Same in winter and summer

    D.

     Not dependent on season


  3. An evaporator is also known as

  4. A.

     Freezing coil

    B.

     Cooling coil

    C.

     Chilling coil

    D.

     All of these


  5. In a refrigeration cycle, the flow of refrigerant is controlled by

  6. A.

     Compressor

    B.

     Condenser

    C.

     Evaporator

    D.

     Expansion valve


  7. Vapour compression refrigeration is somewhat like

  8. A.

     Carnot cycle

    B.

     Reversed Carnot cycle

    C.

     None of the above

    D.


  9. At lower temperatures and pressures, the latent heat of vaporisation of a refrigerant

  10. A.

     decreases

    B.

     increases

    C.

     remains same

    D.

     depends on other factors


  11. A refrigeration cycle operates between condenser temperature of + 27°C and evaporator temperature of -23°C. The Carnot coefficient of performance of cycle will be

  12. A.

     0.2

    B.

     1.2

    C.

     5

    D.

     6


  13. The bypass factor (B. P. F.) in case of sensible heating of air is (Where td₁ = Dry bulb temperature of air entering the heating coil, td₂ = Dry bulb temperature of air leaving the heating coil, and td₃ = Dry bulb temperature of heating coil)

  14. A.

     (td₂ - td₃)/(td₃ - td₁)

    B.

     (td₃ - td₂)/(td₃ - td₁)

    C.

     (td₃ - td₁)/(td₂ - td₃)

    D.

     (td₃ - td₁)/(td₃ - td₂)


  15. The general rule for rating refrigeration systems (excepting for CO₂ system) is to approximate following h.p. per ton of refrigeration

  16. A.

     0.1 to 0.5 h.p. per ton of refrigeration

    B.

     0.5 to 0.8 h.p. per ton of refrigeration

    C.

     1 to 2 h.p. per ton of refrigeration

    D.

     2 to 5 h.p. per ton of refrigeration


  17. The freezing point of R-12 is

  18. A.

     -86.6°C

    B.

     -95.2°C

    C.

     -107.7°C

    D.

     -135.8°C


  19. The coefficient of performance (C.O.P.) of a refrigerator working as a heat pump is given by

  20. A.

     (C.O.P.)P = (C.O.P.)R + 2

    B.

     (C.O.P.)P = (C.O.P.)R + 1

    C.

     (C.O.P)P = (C.O.P)R - 1

    D.

     (C.O.P)P = (C.O.P)R