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

  • The formation of frost on cooling coils in a refrigerator


  • Options
  • A. increases heat transfer
  • B. improves C.O.P. of the system
  • C. increases power consumption
  • D. reduces power consumption

  • Correct Answer
  • increases power consumption 

    • Heat Transfer, Refrigeration and Air Conditioning problems

    Search Results

    • 1. The by-pass factor for a cooling coil

    • Options
    • A. increases with increase in velocity of air passing through it
    • B. decreases with increase in velocity of air passing through it
    • C. remains unchanged with increase in velocity of air passing through it
    • D. may increase or decrease with increase in velocity of air passing through it depending upon the condition of air entering
      • Discuss
    • 2. The process of heat transfer from a hot body to a cold body, in a straight line, without affecting the intervening medium, is called radiation.

    • Options
    • A. True
    • B. False
      • Discuss
    • 3. Fourier's law of heat conduction is (where Q = Amount of heat flow through the body in unit time, A = Surface area of heat flow, taken at right angles to the direction of heat flow, dT = Temperature difference on the two faces of the body, dx = Thickness of the body, through which the heat flows, taken along the direction of heat flow, and k = Thermal conductivity of the body)

    • Options
    • A.
    • B.
    • C.
    • D.
      • Discuss
    • 4. The subcooling in a refrigeration cycle

    • Options
    • A. does not alter C.O.P.
    • B. increases C.O.P.
    • C. decreases C.O.P.
    • D. none of these
      • Discuss
    • 5. Degree of saturation or percentage humidity is

    • Options
    • A. the mass of water vapour present in 1 m3 of dry air
    • B. the mass of water vapour present in 1 kg of dry air
    • C. the ratio of the actual mass of water vapour in a unit mass of dry air to the mass of water vapour in the same mass of dry air when it is saturated at the same temperature and pressure.
    • D. the ratio of actual mass of water vapour in a given volume of moist air to the mass of water vapour in the same volume of saturated air at the same temperature and pressure
      • Discuss
    • 6. The sensible heat factor during cooling and dehumidification process is given by (where h1 = Enthalpy of air entering the cooling coil, h2 = Enthalpy of air leaving the cooling coil, and hA = Enthalpy of air at the end of dehumidification process)

    • Options
    • A.
    • B.
    • C.
    • D.
      • Discuss
    • 7. The optimum effective temperature for human comfort is

    • Options
    • A. higher in winter than in summer
    • B. lower in winter than in summer
    • C. same in winter and summer
    • D. not dependent on season
      • Discuss
    • 8. Defrosting of a refrigerator may be done by stopping the compressor for a short period.

    • Options
    • A. Correct
    • B. Incorrect
      • Discuss
    • 9. A water cooled condenser operates at a __________ condensing temperature than an air-cooled condenser.

    • Options
    • A. higher
    • B. lower
      • Discuss
    • 10. For ammonia refrigerating systems, the tubes of a shell and tube condenser are made of

    • Options
    • A. copper
    • B. aluminium
    • C. steel
    • D. brass
      • Discuss

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