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Chemical Engineering :: Heat Transfer

  1. The type of liquor circulation system to be ' employed in evaporators (viz. natural or forced circulation) is determined mainly by the __________ of the liquid.

  2. A.
    viscosity
    B.
    density
    C.
    thermal conductivity
    D.
    corrosive nature

  3. In case of surface condensers, a straight line is obtained on plotting __________ on an ordinary graph paper.

  4. A.
    1/-0.8
    B.
    -0.8
    C.
    -2
    D.
    1/-2

  5. Thermal diffusivity is the most important in heat transfer by

  6. A.
    conduction
    B.
    radiation
    C.
    condensation
    D.
    natural convection

  7. (NGr x NPr) is called the __________ number.

  8. A.
    Graetz
    B.
    Reyleigh
    C.
    Nusselt
    D.
    Stanton

  9. A dephlegmator is a

  10. A.
    total condenser
    B.
    vacuum evaporator
    C.
    partial condenser
    D.
    double pipe heat exchanger

  11. A tank painted with which of the following coloured paints, would heat up maximum by radiation from sun ?

  12. A.
    Yellow paint
    B.
    White paint
    C.
    Black paint
    D.
    Grey paint

  13. The separation of liquid droplets from the vapor is done by a/an __________ , in the evaporators.

  14. A.
    steam ejector
    B.
    entrainment separator
    C.
    compressor
    D.
    vacuum pump

  15. Fouling factor for a heat exchanger is given by (where, U1 = heat transfer co-efficient of dirty surface U2 = heat transfer co-efficient of clean surface)

  16. A.
    U1 - U2
    B.
    C.
    D.
    U2 - U1

  17. If a single tube pass heat exchanger is converted to two pass, then for the same flow rate, the pressure drop per unit length in tube side will

  18. A.
    increase by 1.8 times
    B.
    decrease by 22
    C.
    increase by 216
    D.
    remain unchanged

  19. A steel sphere of radius 0.1 m at 400°K is immersed in an oil at 300°K. If the centre of the sphere reaches 350°K in 20 minutes, how long will it take for a 0.05 m radius steel sphere to reach the same temperature (at the centre) under identical conditions ? Assume that the conductive heat transfer co-efficient is infinitely large.

  20. A.
    5 minutes
    B.
    10 minutes
    C.
    20 minutes
    D.
    40 minutes