Heat Transfer, Refrigeration and Air Conditioning problems
- 1. During sensible heating of air __________ decreases.
Options- A. wet bulb temperature
- B. relative humidity
- C. dry bulb temperature
- D. specific humidity Discuss
Correct Answer: relative humidity
- 2. 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
Correct Answer: free convection
- 3. 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
Correct Answer: copper
- 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
Correct Answer: the better insulation must be put inside
- 5. 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
Correct Answer: convection
- 6. The lowest temperature during the cycle in a vapour compression system occurs after
Options- A. compression
- B. expansion
- C. condensation
- D. evaporation Discuss
Correct Answer: evaporation
- 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
Correct Answer: cooled and humidified
- 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
Correct Answer: sulphur dioxide
- 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
Correct Answer: absorber, generator and liquid pump
- 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
Correct Answer: all of the above
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