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Chemical Engineering :: Heat Transfer

  1. In a gas-liquid shell and tube heat exchanger, the

  2. A.
    presence of a non-condensible gas decreases the condensing film co-efficient.
    B.
    gases under high pressure are routed through the tube side, because high pressure gases are corrosive in nature.
    C.
    gases to be heated/cooled is normally routed through the shell side, because the corrosion caused by the cooling water or steam condensate remain localised to the tubes.
    D.
    all 'a', 'b' & 'c'

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  3. Which is the most suitable for the concentration of foamy & frothy liquors ?

  4. A.
    Agitated film evaporator
    B.
    Long tube vertical evaporator
    C.
    Open pan evaporator
    D.
    None of these

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  5. Boiling point elevation of an ideal solution

  6. A.
    increases rapidly with temperature rise.
    B.
    decreases rapidly with temperature rise
    C.
    in independent of pressure.
    D.
    both (b) and (c).

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  7. The rate of heat transfer is a product of overall heat transfer co-efficient, the difference in temperature and the

  8. A.
    heating volume
    B.
    heat transfer area
    C.
    Nusselt number
    D.
    none of these

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  9. Which of the following has the lowest overall heat transfer co-efficient ?

  10. A.
    Dowtherm
    B.
    Molten sodium
    C.
    Water
    D.
    Air

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  11. Which of the following has the minimum absorptivity ?

  12. A.
    Aluminium foil
    B.
    Coal dust
    C.
    Refractory bricks
    D.
    Iron plates

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  13. A black body when hot, emits heat radiation of __________ wavelengths.

  14. A.
    small
    B.
    large
    C.
    all
    D.
    one fixed

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  15. A composite wall consists of two plates A and B placed in series normal to the flow of heat. The thermal conductivities are kA and kB and the specific heat capacities are CPA and CPB for plates A and B respectively. Plate B has twice the thickness of plate A. At steady state, the temperature difference across plate A is greater than that across plate B, when

  16. A.
    CPA > CPB
    B.
    CPA < CPB
    C.
    kA < 0.5kB
    D.
    kA>2 kB

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  17. Vibrations in the tubes of a shell and tube heat exchanger is induced due to the

  18. A.
    flow of fluid on the tube and shell sides.
    B.
    oscillations in the flow of shell/tube sides fluid.
    C.
    vibrations transmitted through piping and/or supports due to external reasons.
    D.
    all (a), (b) and (c)

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  19. Heat transfer by conduction in the turbulent core of a fluid flowing through a heated pipe is negligible, if the value of Prandtl number is

  20. A.
    0.2
    B.
    0.4
    C.
    0.6
    D.
    0.8

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