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Home ‣ Mechanical Engineering ‣ Heat Transfer, Refrigeration and Air Conditioning Comments
  • Question

  • Which of the following statement is correct?


  • Options
  • A. A grey body is one which absorbs all radiations incident on it.
  • B. At thermal equilibrium, the emissivity and absorptivity are same.
  • C. The energy absorbed by a body to the total energy falling on it, is called emissivity.
  • D. A perfect body is one which is black in colour.

  • Correct Answer
  • At thermal equilibrium, the emissivity and absorptivity are same. 

    • Heat Transfer, Refrigeration and Air Conditioning problems

    Search Results

    • 1. Bell-Coleman cycle is a

    • Options
    • A. reversed Carnot cycle
    • B. reversed Otto cycle
    • C. reversed Joule cycle
    • D. reversed Rankine cycle
      • Discuss
    • 2. The horizontal and uniformly spaced lines on a psychrometric chart indicates relative humidity.

    • Options
    • A. Correct
    • B. Incorrect
      • Discuss
    • 3. 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
    • 4. 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
    • 5. 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
    • 6. The sulphur sticks, in case of leakage of ammonia refrigerant, gives white smoke.

    • Options
    • A. True
    • B. False
      • Discuss
    • 7. The transfer of heat from one body to another takes place only when there is a temperature difference between the bodies.

    • Options
    • A. Yes
    • B. No
      • Discuss
    • 8. During gas charging in an ammonia vapour compression system, the connection is made at the compressor outlet.

    • Options
    • A. Agree
    • B. Disagree
      • Discuss
    • 9. The water, alcohol and ammonia have same refrigerating effect at different altitudes.

    • Options
    • A. Yes
    • B. No
      • Discuss
    • 10. The wet bulb temperature at 100% relative humidity is __________ dew point temperature.

    • Options
    • A. same as
    • B. lower than
    • C. higher than
      • Discuss

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