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Home Mechanical Engineering Heat Transfer, Refrigeration and Air Conditioning Comments

  • Question
  • 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

  • Correct Answer
  • convection 


  • Heat Transfer, Refrigeration and Air Conditioning problems


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    • 1. 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
    • 2. 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
    • 3. The process of heat transfer from one particle of the fluid to another by the actual movement of the fluid particles due to difference of density caused by temperature of the particle is known as

    • Options
    • A. conduction
    • B. free convection
    • C. forced convection
    • D. radiation
    • Discuss
    • 4. During sensible heating of air __________ decreases.

    • Options
    • A. wet bulb temperature
    • B. relative humidity
    • C. dry bulb temperature
    • D. specific humidity
    • Discuss
    • 5. The thermostatic expansion valve is also called

    • Options
    • A. constant pressure valve
    • B. constant temperature valve
    • C. constant superheat valve
    • D. none of these
    • Discuss
    • 6. The lowest temperature during the cycle in a vapour compression system occurs after

    • Options
    • A. compression
    • B. expansion
    • C. condensation
    • D. evaporation
    • Discuss
    • 7. 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
    • 8. The refrigerant used in small-tonnage commercial machines (hermetically sealed units) is

    • Options
    • A. ammonia
    • B. carbon dioxide
    • C. sulphur dioxide
    • D. R-12
    • Discuss
    • 9. 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
    • 10. 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


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