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Home Mechanical Engineering Heat Transfer, Refrigeration and Air Conditioning Comments

  • Question
  • For a white body, absorptivity (? ) = 0, reflectivity (?) = 1 and transmittivity (?) = 0.


  • Options
  • A. Correct
  • B. Incorrect

  • Correct Answer
  • Correct 


  • Heat Transfer, Refrigeration and Air Conditioning problems


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    • 1. For evaporators and condensers, for the given conditions, the logarithmic mean temperature difference (tm) for parallel flow is __________ that for counter flow.

    • Options
    • A. equal to
    • B. less than
    • C. greater than
    • Discuss
    • 2. The automobile radiator is a heat exchanger of

    • Options
    • A. parallel flow type
    • B. counter flow type
    • C. cross flow type
    • D. regenerator type
    • Discuss
    • 3. The wave length corresponding to the maximum energy is inversely proportional to the absolute temperature. This statement is called Planck's law.

    • Options
    • A. Yes
    • B. No
    • Discuss
    • 4. A vapour absorption refrigerator uses __________ as a refrigerant.

    • Options
    • A. water
    • B. ammonia
    • C. freon
    • D. aqua-ammonia
    • Discuss
    • 5. The material of pipe lines for a system using ammonia as a refrigerant should be copper.

    • Options
    • A. Yes
    • B. No
    • Discuss
    • 6. The use of heat exchangers is made in

    • Options
    • A. radiators in automobile
    • B. condensers and boilers in steam plants
    • C. condensers and evaporators in refrigeration and air conditioning units
    • D. all of the above
    • Discuss
    • 7. The ratio of the thickness of thermal boundary layer to the thickness of hydrodynamic boundary layer is equal to (Prandtl number)n, where n is equal to

    • Options
    • A. -1/3
    • B. -2/3
    • C. 1
    • D. -1
    • Discuss
    • 8. The sensible heat factor during the heating and humidification process is given by (where h1 = Enthalpy of air entering the heating coil, h2 = Enthalpy of air leaving the heating coil, and hA = Enthalpy of air at the end of humidification process)

    • Options
    • A.
    • B.
    • C.
    • D.
    • Discuss
    • 9. The horizontal and uniformly spaced lines on a psychrometric chart indicates relative humidity.

    • Options
    • A. Correct
    • B. Incorrect
    • Discuss
    • 10. Bell-Coleman cycle is a

    • Options
    • A. reversed Carnot cycle
    • B. reversed Otto cycle
    • C. reversed Joule cycle
    • D. reversed Rankine cycle
    • Discuss


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