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Home Mechanical Engineering Heat Transfer, Refrigeration and Air Conditioning Comments

  • Question
  • Thermal diffusivity of a substance is


  • Options
  • A. directly proportional to the thermal conductivity
  • B. inversely proportional to density of substance
  • C. inversely proportional to specific heat
  • D. all of the above

  • Correct Answer
  • all of the above 


  • Heat Transfer, Refrigeration and Air Conditioning problems


    Search Results


    • 1. The process of removing moisture from the air, without change in its dry bulb temperature, is called dehumidification.

    • Options
    • A. Correct
    • B. Incorrect
    • Discuss
    • 2. In a heat exchanger with one fluid evaporating or condensing, the surface area required is least in

    • Options
    • A. parallel flow
    • B. counter flow
    • C. cross flow
    • D. all of these
    • Discuss
    • 3. Thermal conductivity of air increases with rise in temperature.

    • Options
    • A. Correct
    • B. Incorrect
    • Discuss
    • 4. The emissivity for a black body is

    • Options
    • A. 0
    • B. 0.5
    • C. 0.75
    • D. 1
    • Discuss
    • 5. A heat pump working on a reversed Carnot cycle has a C.O.P. of 5. It works as a refrigerator taking 1 kW of work input. The refrigerating effect will be

    • Options
    • A. 1 kW
    • B. 2 kW
    • C. 3 kW
    • D. 4 kW
    • Discuss
    • 6. Fouling factor is used

    • Options
    • A. in heat exchanger design as a safety factor
    • B. in case of Newtonian fluids
    • C. when a liquid exchanges heat with a gas
    • D. none of the above
    • Discuss
    • 7. Which of the following refrigerant has the lowest freezing point?

    • Options
    • A. R-11
    • B. R-12
    • C. R-22
    • D. Ammonia
    • Discuss
    • 8. The critical pressure of a liquid is the pressure

    • Options
    • A. above which a liquid will remain a liquid
    • B. above which a liquid will explode
    • C. above which a liquid will always convert into a vapour
    • D. below which a liquid will always be in vapour form
    • Discuss
    • 9. Free convection flow depends on

    • Options
    • A. density
    • B. coefficient of viscosity
    • C. gravitational force
    • D. all of these
    • Discuss
    • 10. Air conditioning means

    • Options
    • A. cooling
    • B. heating
    • C. dehumidifying
    • D. all of these
    • Discuss


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