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Mechanical Engineering :: Refrigeration and Air Conditioning

  1. Choose the wrong statement

  2. A.

     Temperature of medium being cooled must be below that of the evaporator

    B.

     Refrigerant leaves the condenser as liquid

    C.

     All solar thermally operated absorption systems are capable only of intermittent operation

    D.

     Frost on evaporator reduces heat transfer

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  3. In a refrigeration system, the expansion device is connected between the

  4. A.

     Compressor and condenser

    B.

     Condenser and receiver

    C.

     Receiver and evaporator

    D.

     Evaporator and compressor

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  5. The human body feels comfortable when the heat stored in the body is

  6. A.

     Positive

    B.

     Negative

    C.

     Zero

    D.

     None of these

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  7. The emissivity of a polished silver body is _________ as compared to black body.

  8. A.

     Same

    B.

     Low

    C.

     Very low

    D.

     High

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  9. Relative humidity is given by (where pv = Partial pressure of water vapour, pb = Barometric pressure, ps = Pressure of saturated air, pd = Pressure at dry bulb temperature, pw = Saturation pressure corresponding to wet bulb temperature, and μ = Degree of saturation)

  10. A.

     0.622 Pv / (Pb - Pv)

    B.

     μ/[1 - (1 - μ) (Ps/Pb)]

    C.

     [Pv (Pb - Pd)]/ [Pd (Pb - Pv)]

    D.

     None of these

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  11. In which of the following refrigeration system, waste heat can be effectively used?

  12. A.

     Vapour compression cycle

    B.

     Vapour absorption cycle

    C.

     Air refrigeration cycle

    D.

     None of these

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  13. Environmental protection agencies advice against the use of chlorofluorocarbon refrigerants since

  14. A.

     These react with water vapour and cause acid rain

    B.

     These react with plants and cause greenhouse effect

    C.

     These react with oxygen and cause its depletion

    D.

     These react with ozone layer

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  15. The comfort conditions in air conditioning are at (where DBT = Dry bulb temperature, and RH = Relative humidity)

  16. A.

     25°C DBT and 100% RH

    B.

     20°C DBT and 80% RH

    C.

     22°C DBT and 60% RH

    D.

     25°C DBT and 40% RH

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  17. In a vapour absorption refrigeration system, the compressor of the vapour compression system is replaced by

  18. A.

     Liquid pump

    B.

     Generator

    C.

     Absorber and generator

    D.

     Absorber, generator and liquid pump

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  19. Which of the following statement is correct?

  20. A.

     The constant enthalpy lines are also constant wet bulb temperature lines

    B.

     The wet bulb and dry bulb temperature are equal at saturation condition

    C.

     The wet bulb temperature is a measure of enthalpy of moist air

    D.

     All of the above

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