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Chemical Engineering :: Heat Transfer

  1. Heat transfer rate described by Fourier's law will decrease, if the __________ increases.

  2. A.
    thermal conductivity
    B.
    thickness
    C.
    temperature difference
    D.
    heat transfer area

  3. A black body does not __________ radiation.

  4. A.
    absorb or emit
    B.
    refract
    C.
    reflect
    D.
    both(b) & (c)

  5. The capacity of double-effect evaporator is less than half of the capacity of two single effects, each of which is operating over same terminal temperature difference, when the

  6. A.
    solution has an elevation of boiling point.
    B.
    evaporators operate under vacuum.
    C.
    evaporators opreate at atmospheric pressure.
    D.
    none of these.

  7. Peclet number (Pe) is given by

  8. A.
    Pe = Re.Pr
    B.
    Pe = Re/Pr
    C.
    Pe = Pr/Re
    D.
    Pe = Nu.Re

  9. Nusselt number is the ratio of the

  10. A.
    temperature gradient of the wall to that across the entire pipe.
    B.
    temperature difference to the temperature gradient at the wall.
    C.
    heat flux at the wall to that across the entire pipe.
    D.
    none of these

  11. Prandtl number is the ratio of

  12. A.
    momentum diffusivity to mass diffusivity.
    B.
    momentum diffusivity to thermal diffusivity.
    C.
    thermal diffusivity to mass diffusivity.
    D.
    thermal diffusivity to momentum diffusivity.

  13. Which of the following parameters is increased by use of finned tube in a multipass shell and tube heat exchanger ?

  14. A.
    Tube side pressure drop and the heat transfer rate.
    B.
    Convective heat transfer co-efficient.
    C.
    Effective tube surface area for convective heat transfer.
    D.
    All (a) (b) and (c).

  15. Forced circulation evaporators are useful for the concentration of viscous, salting and scale forming liquors. Which of the following is a forced circulation evaporator?

  16. A.
    Long vertical evaporator
    B.
    Horizontal tube evaporator
    C.
    Agitated film evaporator
    D.
    Calenderia vertical tube evaporator

  17. "The ratio of the total emissive power to the absorptivity for all bodies is same at ther-mal equilibrium". This is __________ law.

  18. A.
    Kirchoffs
    B.
    Planck's
    C.
    Wien's displacement
    D.
    Stefan-Boltzman

  19. View factor is important in heat transfer by

  20. A.
    steady state conduction
    B.
    natural convection
    C.
    forced convection
    D.
    radiation