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Chemical Engineering :: Heat Transfer

  1. Low thermal conductivity of heat insulating materials is due to its

  2. A.
    dense structure.
    B.
    high proportion of air space.
    C.
    high specific heat.
    D.
    none of these.

  3. The most conducive surface for dropwise condensation to occur is the __________ surface.

  4. A.
    coated
    B.
    oily
    C.
    glazed & polished
    D.
    smooth

  5. In an interphase heat transfer process, the equilibrium state corresponds to equality of temperature in the two phases, while the condition for equilibrium in an interphase mass transfer process is equality of

  6. A.
    concentrations
    B.
    chemical potentials
    C.
    activity co-efficients
    D.
    mass transfer co-efficients

  7. Calburn analogy is applicable for the value of Prandtl number from

  8. A.
    0.001 to 1
    B.
    0.6 to 120
    C.
    0.5 to 5
    D.
    120 to 400

  9. Pick out the correct equation.

  10. A.
    jH = (St)(Pr)2/3 = f/2
    B.
    jH = (St)(Pr)1/3 = f/2
    C.
    jH = (St)2/3(Pr) = f/2
    D.
    jH = (St)1/3(Pr) = f/2

  11. Multiple effect evaporators ar used to

  12. A.
    increase the steam economy & decrease the capacity.
    B.
    increase the steam economy & the capacity.
    C.
    decrease the steam economy & the capacity.
    D.
    decrease the steam economy & increase the capacity.

  13. Prandtl number is given by


  14. Small scale evaporation is done in a

  15. A.
    heat exchanger
    B.
    condenser
    C.
    multiple effect evaporator
    D.
    steam jacketed kettle

  16. Heat exchanger tubes are never made of

  17. A.
    plain carbon steel
    B.
    stainless steel
    C.
    lead
    D.
    copper

  18. At constant temperature, the thermal conductivities of gases __________ with rise in pressure.

  19. A.
    decrease
    B.
    increase
    C.
    remain unchanged
    D.
    may increase or decrease; depends on the pressure