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

  • The rato of energy transferred by convection to that by conduction is called


  • Options
  • A. Stanton number
  • B. Nusselt number
  • C. Biot number
  • D. Peclet number

  • Correct Answer
  • Nusselt number 

    • Heat Transfer, Refrigeration and Air Conditioning problems

    Search Results

    • 1. The heat transfer by conduction through a thick cylinder(Q) is given by (where T1 = Higher temperature, T2 = Lower temperature, r1 = Inside radius, r2 = Outside radius, l = Length of cylinder, and k = Thermal conductivity)

    • Options
    • A.
    • B.
    • C.
    • D.
      • Discuss
    • 2. If the evaporator temperature is kept constant, the coefficient of performance of a refrigeration cycle __________ with the increase in condenser temperature.

    • Options
    • A. increases
    • B. decreases
      • Discuss
    • 3. Dehydration is the process of removing water vapour from the surrounding air.

    • Options
    • A. True
    • B. False
      • Discuss
    • 4. The capacity of the cooling tower and spray ponds __________ as the wet bulb temperature of air decreases.

    • Options
    • A. increases
    • B. decreases
      • Discuss
    • 5. The evaporator used in house-hold refrigerators is

    • Options
    • A. frosting evaporator
    • B. non-frosting evaporator
    • C. defrosting evaporator
    • D. none of these
      • Discuss
    • 6. Upto the critical radius of insulation,

    • Options
    • A. added insulation will increase heat loss
    • B. added insulation will decrease heat loss
    • C. convective heat loss will be less than conductive heat loss
    • D. heat flux will decrease
      • Discuss
    • 7. The critical thickness of insulation is the ratio of thermal conductivity of the insulating material (k) to the heat transfer coefficient at the outer surface of the insulation (h0).

    • Options
    • A. True
    • B. False
      • Discuss
    • 8. Pressure of water vapour is given by

    • Options
    • A.
    • B.
    • C.
    • D. none of these
      • Discuss
    • 9. In counter-current flow heat exchanger, the logarithmic temperature difference between the fluids is __________ as compared to parallel flow heat exchanger.

    • Options
    • A. same
    • B. less
    • C. greater
      • Discuss
    • 10. For a given dry bulb temperature, as the relative humidity __________ the wet bulb temperature will increase.

    • Options
    • A. increases
    • B. decreases
      • Discuss

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