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Home Mechanical Engineering Heat Transfer, Refrigeration and Air Conditioning Comments

  • Question
  • The boiling point of R-12 is about - 30°C.


  • Options
  • A. True
  • B. False

  • Correct Answer
  • True 


  • Heat Transfer, Refrigeration and Air Conditioning problems


    Search Results


    • 1. In a parallel flow heat exchanger, the rate of flow of heat and the rate of decrease of temperature are maximum.

    • Options
    • A. Yes
    • B. No
    • Discuss
    • 2. The refrigerant after condensation process is cooled below the saturation temperature before throttling. Such a process is called

    • Options
    • A. sub-cooling or under-cooling
    • B. super-cooling
    • C. normal cooling
    • D. none of these
    • Discuss
    • 3. The fluids used in electrolux refrigerator are

    • Options
    • A. water and hydrogen
    • B. ammonia and hydrogen
    • C. ammonia, water and hydrogen
    • D. none of these
    • Discuss
    • 4. The overall coefficient of heat transfer is used in problems of

    • Options
    • A. conduction
    • B. convection
    • C. radiation
    • D. conduction and convection
    • Discuss
    • 5. During heating and humidification, the final relative humidity of air

    • Options
    • A. is higher than that of the entering air
    • B. is lower than that of the entering air
    • C. can be lower or higher than that of the entering air
    • D. none of the above
    • Discuss
    • 6. It is desired to condition the outside air from 70% relative humidity and 45° C dry bulb temperature to 50% relative humidity and 25° C dry bulb temperature (room condition). The practical arrangement will be

    • Options
    • A. dehumidification
    • B. cooling and humidification
    • C. cooling and dehumidification
    • D. dehumidification and pure sensible cooling
    • Discuss
    • 7. The heat transfer from a hot body to a cold body is directly proportional to the surface area and difference of temperatures between the two bodies. This statement is called

    • Options
    • A. First law of thermodynamics
    • B. Newton's law of cooling
    • C. Newton's law of heating
    • D. Stefan's law
    • Discuss
    • 8. The absolute humidity is the mass of water vapour present in 1 m3 of dry air.

    • Options
    • A. Agree
    • B. Disagree
    • Discuss
    • 9. In a lithium bromide absorption refrigeration system

    • Options
    • A. lithium bromide is used as a refrigerant and water as an absorbent
    • B. water is used as a refrigerant and lithium bromide as an absorbent
    • C. ammonia is used as a refrigerant and lithium bromide as an absorbent
    • D. none of the above
    • Discuss
    • 10. 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


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