Discussion
Home ‣ Mechanical Engineering ‣ Heat Transfer, Refrigeration and Air Conditioning Comments
- Question
An infinite parallel planes with emissivities e1 and e2, the interchange factor for radiation from surface 1 to surface 2 is given by
Options- A.
- B.
- C. e1 + e2
- D. e1e2
- Correct Answer
-
- 1. R-12 is generally preferred over R-22 in deep freezers since
Options- A. it has low operating pressures
- B. it gives higher coefficient of performance
- C. it is miscible with oil over large range of temperatures
- D. all of the above Discuss
- 2. The refrigerant widely used in domestic refrigerators is
Options- A. ammonia
- B. carbon dioxide
- C. sulphur dioxide
- D. R-12 Discuss
- 3. The mass of water vapour present in 1 kg of dry air, is called humidity ratio.
Options- A. True
- B. False Discuss
- 4. The unit of overall coefficient of heat transfer is
Options- A. W/m2K
- B. W/m2
- C. W/mK
- D. W/m Discuss
- 5. The ratio of actual heat transfer to the maximum possible heat transfer is known as heat exchanger effectiveness.
Options- A. Agree
- B. Disagree Discuss
- 6. Hydrogen is used in electrolux refrigeration system so as to __________ the rate of evaporation of the liquid ammonia passing through the evaporator.
Options- A. equalise
- B. reduce
- C. increase Discuss
- 7. Which of the following statement is correct?
Options- A. In vapour absorption refrigerator, the compression of refrigerent is avoided.
- B. Sub-cooling can be achieved by circulating more quantity of cooling water through the condenser.
- C. In vapour compression refrigeration, the vapour is drawn in the compressor cylinder during its suction stroke and is compressed adiabatically during the compression stroke.
- D. all of the above Discuss
- 8. The cooling system used for supersonic aircrafts and rockets is
Options- A. simple air cooling system
- B. boot-strap air cooling system
- C. reduced ambient air cooling system
- D. regenerative air cooling system Discuss
- 9. The ratio of actual mass of water vapour in a given volume of moist air to the mass of water vapour in the same volume of saturated air at the same temperature and pressure, is called
Options- A. humidity ratio
- B. relative humidity
- C. absolute humidity
- D. degree of saturation Discuss
- 10. The space between the two walls of a thermos flask is evacuated because vacuum is a __________ conductor of heat.
Options- A. good
- B. bad Discuss
Heat Transfer, Refrigeration and Air Conditioning problems
Search Results
Correct Answer: it is miscible with oil over large range of temperatures
Correct Answer: R-12
Correct Answer: True
Correct Answer: W/m2K
Correct Answer: Agree
Correct Answer: increase
Correct Answer: all of the above
Correct Answer: regenerative air cooling system
Correct Answer: relative humidity
Correct Answer: bad
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