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Home Mechanical Engineering Heat Transfer, Refrigeration and Air Conditioning Comments

  • Question
  • The refrigerant used in small-tonnage commercial machines (hermetically sealed units) is


  • Options
  • A. ammonia
  • B. carbon dioxide
  • C. sulphur dioxide
  • D. R-12

  • Correct Answer
  • sulphur dioxide 


  • Heat Transfer, Refrigeration and Air Conditioning problems


    Search Results


    • 1. When the air is passed through an insulated chamber having sprays of water maintained at a temperature higher than the dew point temperature of entering air but lower than its dry bulb temperature, then the air is said to be

    • Options
    • A. cooled and humidified
    • B. cooled and dehumidified
    • C. heated and humidified
    • D. heated and dehumidified
    • Discuss
    • 2. The lowest temperature during the cycle in a vapour compression system occurs after

    • Options
    • A. compression
    • B. expansion
    • C. condensation
    • D. evaporation
    • Discuss
    • 3. The process of heat transfer from one particle of the body to another by the actual motion of the heated particles, is called

    • Options
    • A. conduction
    • B. convection
    • C. radiation
    • Discuss
    • 4. A steam pipe is to be lined with two layers of insulating materials of different thermal conductivities. For the minimum heat transfer,

    • Options
    • A. the better insulation must be put inside
    • B. the better insulation must be put outside
    • C. one could place either insulation on either side
    • D. one should take into account the steam temperature before deciding as to which insulation is put where
    • Discuss
    • 5. The material of pipe lines for a system using freon as a refrigerant should be

    • Options
    • A. brass
    • B. copper
    • C. steel
    • D. aluminium
    • Discuss
    • 6. In a vapour absorption refrigeration system, the compressor of the vapour compression system is replaced by

    • Options
    • A. liquid pump
    • B. generator
    • C. absorber and generator
    • D. absorber, generator and liquid pump
    • Discuss
    • 7. A refrigerant compressor is used to

    • Options
    • A. raise the pressure of the refrigerant
    • B. raise the temperature of the refrigerant
    • C. circulate the refrigerant through the refrigerating system
    • D. all of the above
    • Discuss
    • 8. In aircraft, air refrigeration Cycle is used because of

    • Options
    • A. low weight per tonne of refrigeration
    • B. high heat transfer rate
    • C. low temperature at high altitudes
    • D. higher coefficient of performance
    • Discuss
    • 9. The pressure at the inlet of a refrigerant compressor is called

    • Options
    • A. suction pressure
    • B. discharge pressure
    • C. critical pressure
    • D. back pressure
    • Discuss
    • 10. The power per tonne of refrigeration is

    • Options
    • A. 3.5/C.O.P.
    • B. C.O.P/3.5
    • C. 3.5 x C.O.P.
    • D. none of these
    • Discuss


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