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

  • The highest thermal diffusivity is of


  • Options
  • A. iron
  • B. lead
  • C. concrete
  • D. wood

  • Correct Answer
  • lead 

    • Heat Transfer, Refrigeration and Air Conditioning problems

    Search Results

    • 1. The C.O.P. of an absorption type refrigerator is given by (where T1 = Temperature at which the working substance receives heat, T2 = Temperature of cooling water, and T3 = Evaporator temperature)

    • Options
    • A.
    • B.
    • C.
    • D.
      • Discuss
    • 2. The heat transfer by radiation __________ a medium.

    • Options
    • A. requires
    • B. does not require
      • Discuss
    • 3. An electrolux refrigerator is called a __________ absorption system.

    • Options
    • A. single fluid
    • B. two fluids
    • C. three fluids
      • Discuss
    • 4. The relative humidity decreases as air gets wet.

    • Options
    • A. True
    • B. False
      • Discuss
    • 5. During sensible cooling of air __________ decreases.

    • Options
    • A. wet bulb temperature
    • B. relative humidity
    • C. dry bulb temperature
    • D. specific humidity
      • Discuss
    • 6. 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
    • 7. Thermal diffusivity is a

    • Options
    • A. function of temperature
    • B. physical property of a substance
    • C. dimensionless parameter
    • D. all of these
      • Discuss
    • 8. 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
    • 9. 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
    • 10. 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
      • Discuss

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