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Chemical Engineering :: Heat Transfer

  1. The equivalent diameter for pressure drop is __________ that for heat transfer.

  2. A.
    smaller than
    B.
    greater than
    C.
    equal to
    D.
    not related with

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  3. Controlling heat transfer film co-efficient is the one, which offers __________ resistance to heat transfer.

  4. A.
    no
    B.
    the least
    C.
    the largest
    D.
    lower

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  5. The heat flux (from outside to inside) across an insulating wall with thermal conductivity, K= 0.04 W/m.°K and thickness 0.16m is 10 W/m2. The temperature of the inside wall is - 5°C. The outside wall temperature is

  6. A.
    25°C
    B.
    30°C
    C.
    35°C
    D.
    40°C

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  7. Thermal conductivity of a conducting solid material depends upon its

  8. A.
    temperature
    B.
    porosity
    C.
    both (a) & (b)
    D.
    neither (a) nor (b)

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  9. Pick out the wrong statement.

  10. A.
    The controlling resistance in case of heating of air by condensing steam is in the air film.
    B.
    The log mean temperature difference (LMTD) for counter flow and parallel flow can be theoretically same when any one of the fluids (hot or cold fluid) passes through the heat exchanger at constant temperature.
    C.
    In case of a 1 - 2 shell and tube heat exchanger, the LMTD correction factor value increases sharply, when a temperature cross occurs.
    D.
    Phase change in case of a pure fluid at a given pressure from liquid to vapor or vice-versa occurs at saturation temperature.

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  11. The average heat transfer co-efficient for laminar film condensation on vertical surface is inversely proportional to (where, ΔT = Temperature drop across condensate film )

  12. A.
    (ΔT)2
    B.
    ΔT
    C.
    (ΔT)1/4
    D.
    (ΔT)3/2

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  13. Bulk of the convective heat transfer resistance from a hot tube surface to the fluid flowing in it, is

  14. A.
    in the central core of the fluid.
    B.
    uniformly distributed throughout the fluid.
    C.
    mainly confined to a thin film of fluid near the surface.
    D.
    none of these.

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  15. Which of the following is concerned with both heat and mass transfer ?

  16. A.
    Lewis relationship
    B.
    Nusselt number
    C.
    Kutateladze number
    D.
    Froude number

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  17. A backward feed multiple effect evaporator is better than forward feed for concentrating cold feed, because it provides

  18. A.
    higher economy
    B.
    lower capacity
    C.
    both (a) & (b)
    D.
    lower economy

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  19. A 10 cm dia steam pipe, carrying steam at 180°C, is covered with an insulation (conductivity = 0.6 W/m.°C). It losses heat to the surroundings at 30°C. Assume a heat transfer co-efficient of 0.8 W/m2.°C for heat transfer from surface to the surroundings. Neglect wall resistance of the pipe and film resistance of steam. If the insulation thickness is 2 cms, the rate of heat loss from this insulated pipe will be

  20. A.
    greater than that for uninsulated steam pipe.
    B.
    less than that of the uninsulated steam pipe.
    C.
    equal to that of the uninsulated steam pipe.
    D.
    less than the steam pipe with 5 cms insulation.

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