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Chemical Engineering :: Heat Transfer

  1. Out of 100 kcal/second of incident radiant energy on the surface of a thermally transparent body, 300 kcal/second is reflected back. If the transmissivity of the body is 0.25, the emissivity of the surface will be

  2. A.
    0.35
    B.
    0.45
    C.
    0.55
    D.
    0.85

  3. The purpose of providing a 'catchall' in the vapor line of an evaporator is to

  4. A.
    create vacuum
    B.
    regulate the vapor flow
    C.
    vent the non-condensible gases
    D.
    arrest the entrained liquid

  5. What is the thermal conductivity of a perfect heat insulator ?

  6. A.
    zero
    B.
    one
    C.
    D.
    between 0 and ∞

  7. 'Fouling factor' used in the design of a multipass shell and tube heat exchanger is a

  8. A.
    non-dimensional factor.
    B.
    factor of safety.
    C.
    conversion factor for individual film heat transfer co-efficient to overall heat transfer co-efficient.
    D.
    none of these.

  9. A fluid is flowing inside the inner tube of a double pipe heat exchanger with diameter 'd'. For a fixed mass flow rate, the tube side heat transfer co-efficient for turbulent flow conditions is proportional to

  10. A.
    d0.8
    B.
    d-0.2
    C.
    d-1
    D.
    d-1.8

  11. Prandtl and Reynolds analogy are same, when Prandtl number is

  12. A.
    0.5
    B.
    1
    C.
    > 2
    D.
    1.5

  13. Heat transfer occurs by natural convection because change in temperature causes difference in

  14. A.
    viscosity
    B.
    density
    C.
    thermal conductivity
    D.
    heat capacity

  15. The ratio of kinematic viscosity to thermal diffusivity is called the __________ number.

  16. A.
    Peclet
    B.
    Prandtl
    C.
    Stanton
    D.
    Nusselt