Heat Transfer, Refrigeration and Air Conditioning problems
- 1. The overall coefficient of heat transfer is used in problems of
Options- A. conduction
- B. convection
- C. radiation
- D. conduction and convection Discuss
Correct Answer: conduction and convection
- 2. 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
Correct Answer: ammonia, water and hydrogen
- 3. 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
Correct Answer: sub-cooling or under-cooling
- 4. 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
Correct Answer: Yes
- 5. The boiling point of R-12 is about - 30°C.
Options- A. True
- B. False Discuss
Correct Answer: True
- 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
Correct Answer: cooling and dehumidification
- 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
Correct Answer: Newton's law of cooling
- 8. The absolute humidity is the mass of water vapour present in 1 m3 of dry air.
Options- A. Agree
- B. Disagree Discuss
Correct Answer: Agree
- 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
Correct Answer: water is used as a refrigerant and lithium bromide as an absorbent
- 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
Correct Answer: constant superheat valve
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