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Chemical Engineering :: Heat Transfer

  1. Shell side pressure drop in a shell and tube heat exchanger does not depend upon the

  2. A.
    baffle spacing & shell diameter.
    B.
    tube diameter & pitch.
    C.
    viscosity, density & mass velocity of shell side fluid.
    D.
    none of these.

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  3. In the equation Q = UAΔt; Δt is

  4. A.
    geometric mean temperature difference.
    B.
    arithmetic mean temperature difference.
    C.
    logarithmic mean temperature difference.
    D.
    the difference of average bulk temperatures of hot and cold fluids.

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  5. With increase in porosity, the thermal conductivity of a solid substance

  6. A.
    increases
    B.
    decreases
    C.
    remains unchanged
    D.
    may increase or decrease; depends on the solid

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  7. For an ideal black body

  8. A.
    absorptivity = 1
    B.
    reflectivity = 1
    C.
    emissivity = 0
    D.
    transmissivity = 1

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  9. In Joule's experiment, an insulated container contains 20 kg of water initially at 25°C. It is stirred by an agitator, which is made to turn by a slowly falling body weighing 40 kg through a height of 4 m. The process is repeated 500 times. The acceleration due to gravity is 9.8 ms-2. Neglecting the heat capacity of agitator, the temperature of water (in °C) is

  10. A.
    40.5
    B.
    34.4
    C.
    26.8
    D.
    25

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  11. Fouling factor

  12. A.
    is a dimensionless quantity.
    B.
    does not provide a safety factor for design.
    C.
    accounts for additional resistances to heat flow.
    D.
    none of these.

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  13. In case of vertical tube evaporator, with increase in liquor level, the overall heat transfer co-efficient

  14. A.
    increases
    B.
    decreases
    C.
    is not affected
    D.
    may increase or decrease; depends on the feed

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  15. The steam ejector is used to

  16. A.
    remove condensate from the steam pipelines.
    B.
    create vacuum.
    C.
    superheat the steam.
    D.
    none of these.

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  17. For shell and tube heat exchanger, with increasing heat transfer area, the purchased cost per unit heat transfer area

  18. A.
    increases
    B.
    decreases
    C.
    remains constant
    D.
    passes through a maxima

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  19. The thermal efficiency of a reversible heat engine operating between two given thermal reservoirs is 0.4. The device is used either as a refrigerator or as a heat pump between the same reservoirs. Then the coefficient of performance as a refrigerator (COP)R and the co-efficient of performance as a heat pump (COP)HP are

  20. A.
    (COP)R = (COP)HP = 0.6
    B.
    (COP)R = 2.5; (COP)HP = 1.5
    C.
    (COP)R = 1.5; (COP)HP = 2.5
    D.
    (COP)R = (COP)HP = 2.5

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