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Home Mechanical Engineering Heat Transfer, Refrigeration and Air Conditioning Comments

  • Question
  • The transfer of heat by molecular collision is known as


  • Options
  • A. conduction
  • B. convection
  • C. radiation
  • D. none of these

  • Correct Answer
  • conduction 


  • Heat Transfer, Refrigeration and Air Conditioning problems


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    • 1. The dehumidification process, on the psychrometric chart, is shown by

    • Options
    • A. horizontal Sine
    • B. vertical line
    • C. inclined line
    • D. curved line
    • Discuss
    • 2. The rate of heat flow through a body is . The term is known as temperature gradient.

    • Options
    • A. Yes
    • B. No
    • Discuss
    • 3. The coefficient of performance of a domestic refrigerator is __________ as compared to a domestic air-conditioner.

    • Options
    • A. same
    • B. less
    • C. more
    • Discuss
    • 4. A furnace is made of a red brick wall of thickness 0.5 m and conductivity 0.7 W/mK. For the same heat loss and temperature drop, this can be replaced by a layer of diatomite earth of conductivity 0.14 W/mK and thickness

    • Options
    • A. 0.5 m
    • B. 0.1 m
    • C. 0.2 m
    • D. 0.5 m
    • Discuss
    • 5. The vertical and uniformly spaced lines on a psychrometric chart indicates

    • Options
    • A. dry bulb temperature
    • B. wet bulb temperature
    • C. dew point temperature
    • D. specific humidity
    • Discuss
    • 6. A cube at high temperature is immersed in a constant temperature bath. It loses heat from its top, bottom and side surfaces with heat transfer coefficients of h1, h2 and h3 respectively. The average heat transfer coefficient for the cube is

    • Options
    • A. h1 + h2 + h3
    • B. (h1h2h3)1/3
    • C.
    • D. none of these
    • Discuss
    • 7. During sensible cooling of air, the relative humidity increases.

    • Options
    • A. Yes
    • B. No
    • Discuss
    • 8. Wein's law states that the wave length corresponding to __________ is proportional to the absolute temperature.

    • Options
    • A. minimum energy
    • B. maximum energy
    • Discuss
    • 9. The coefficient of performance of vapour compression refrigeration system is quite __________ as compared to air refrigeration system.

    • Options
    • A. low
    • B. high
    • Discuss
    • 10. In case of sensible heating of air, the coil efficiency is given by (where B.P.F. = By-pass factor)

    • Options
    • A. B.P.F. - 1
    • B. 1 - B.P.F.
    • C.
    • D. 1 + B.RF.
    • Discuss


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