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Home Mechanical Engineering Heat Transfer, Refrigeration and Air Conditioning Comments

  • Question
  • A refrigeration system


  • Options
  • A. removes heat from a low temperature body and delivers it to a high temperature body
  • B. removes heat from a high temperature body and delivers it to a low temperature body
  • C. rejects energy to a low temperature body
  • D. none of the above

  • Correct Answer
  • removes heat from a low temperature body and delivers it to a high temperature body 


  • Heat Transfer, Refrigeration and Air Conditioning problems


    Search Results


    • 1. Thermal conductivity of water __________ with rise in temperature.

    • Options
    • A. remains same
    • B. decreases
    • C. increases
    • D. may increase or decrease depending upon temperature
    • Discuss
    • 2. Reynolds number (RN) is given by (where h = Film coefficient, l = Linear dimension, V = Velocity of fluid, k = Thermal conductivity, t = Temperature, ? = Density of fluid, cp = Specific heat at constant pressure, and ? = Coefficient of absolute viscosity)

    • Options
    • A.
    • B.
    • C.
    • D.
    • Discuss
    • 3. Thermal diffusivity is a

    • Options
    • A. function of temperature
    • B. physical property of a substance
    • C. dimensionless parameter
    • D. all of these
    • Discuss
    • 4. The thickness of thermal and hydrodynamic boundary layer is equal if Prandtl number is

    • Options
    • A. equal to one
    • B. greater than one
    • C. less than one
    • D. equal to Nusselt number
    • Discuss
    • 5. The highest thermal diffusivity is of

    • Options
    • A. iron
    • B. lead
    • C. concrete
    • D. wood
    • Discuss
    • 6. A perfect black body is one which

    • Options
    • A. is black in colour
    • B. absorbs heat radiations of all wave lengths falling on it
    • C. reflects all the heat radiations
    • D. transmits the heat radiations
    • Discuss
    • 7. While designing the refrigeration system of an aircraft, the prime consideration is that the

    • Options
    • A. system has high C.O.P.
    • B. power per TR is low
    • C. mass of refrigerant circulated in the system is low
    • D. mass of the refrigeration equipment is low
    • Discuss
    • 8. The difference between dry bulb temperature and wet bulb temperature, is called

    • Options
    • A. dry bulb depression
    • B. wet bulb depression
    • C. dew point depression
    • D. degree of saturation
    • Discuss
    • 9. The wet bulb temperature lines, on the psychrometric chart, are curved lines.

    • Options
    • A. True
    • B. False
    • Discuss
    • 10. Nusselt number (NN) is given by

    • Options
    • A.
    • B.
    • C.
    • D.
    • Discuss


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