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Home Chemical Engineering Heat Transfer Comments

  • Question
  • For shell and tube heat exchanger, with increasing heat transfer area, the purchased cost per unit heat transfer area


  • Options
  • A. increases
  • B. decreases
  • C. remains constant
  • D. passes through a maxima

  • Correct Answer
  • passes through a maxima 


  • Heat Transfer problems


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    • 1. Economy of a multiple effect evaporator is not influenced much by the

    • Options
    • A. boiling point elevations
    • B. temperature of the feed
    • C. rate of heat transfer
    • D. ratio of the weight of the thin liquor to thick liquor
    • Discuss
    • 2. Thermal conductivity of a conducting solid material depends upon its

    • Options
    • A. temperature
    • B. porosity
    • C. both (a) & (b)
    • D. neither (a) nor (b)
    • Discuss
    • 3. Steam consumption in kg/hr in case of an evaporator is given by (where, C & E are capacity the economy of the evaporator respectively)

    • Options
    • A. C/E
    • B. E/C
    • C. CE
    • D.
    • Discuss
    • 4. The thermal efficiency of a reversible heat engine operating between two given thermal reservoirs is 0.4. The device is used either as a refrigerator or as a heat pump between the same reservoirs. Then the coefficient of performance as a refrigerator (COP)R and the co-efficient of performance as a heat pump (COP)HP are

    • Options
    • A. (COP)R = (COP)HP = 0.6
    • B. (COP)R = 2.5; (COP)HP = 1.5
    • C. (COP)R = 1.5; (COP)HP = 2.5
    • D. (COP)R = (COP)HP = 2.5
    • Discuss
    • 5. Pick out the wrong statement.

    • Options
    • A. In case of heat transfer by purely forced convection, GR/Re2 ? 1.
    • B. The equivalent diameter of heat transfer for a duct of square cross-section (having each side as 'x') is equal to 4x.
    • C. Distillation process is not the same as evaporation.
    • D. The effectiveness of nucleate boiling depends basically on the ease with which the bubbles are formed and detached from the heating surface.
    • Discuss
    • 6. Bulk of the convective heat transfer resistance from a hot tube surface to the fluid flowing in it, is

    • Options
    • A. in the central core of the fluid.
    • B. uniformly distributed throughout the fluid.
    • C. mainly confined to a thin film of fluid near the surface.
    • D. none of these.
    • Discuss
    • 7. Baffles in the shell side of a shell and tube heat exchanger

    • Options
    • A. increase the cross-section of the shell side liquid.
    • B. force the liquid to flow parallel to the bank.
    • C. increase the shell side heat transfer co-efficient.
    • D. decrease the shell side heat transfer co-efficient.
    • Discuss
    • 8. The actual temperature drop across the heating surface in an evaporator depends on the

    • Options
    • A. feed.
    • B. depth of liquid over heating surface.
    • C. pressure difference between steam chest and vapour space.
    • D. all (a), (b) and (c).
    • Discuss
    • 9. Air is to be heated by condensing steam. Two heat exchangers are available (i) a shell and tube heat exchanger and (ii) a finned tube heat exchanger. Tube side heat transfer area are equal in both the cases. The recommended arrangement is

    • Options
    • A. finned tube heat exchanger with air inside and steam outside.
    • B. finned tube heat exchanger with air outside and steam inside.
    • C. shell and tube heat exchanger with air inside tubes and steam on shell side.
    • D. shell and tube heat exchanger with air on shell side and steam inside tubes.
    • Discuss
    • 10. The unit of heat transfer co-efficient in SI unit is

    • Options
    • A. J/M2°K
    • B. W/m2°K
    • C. W/m°K
    • D. J/m°K
    • Discuss


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