Heat Transfer, Refrigeration and Air Conditioning problems
- 1. The comfort conditions in air conditioning are at (where DBT = Dry bulb temperature, and RH = Relative humidity)
Options- A. 25°C DBT and 100% RH
- B. 20°C DBT and 80% RH
- C. 22°C DBT and 60% RH
- D. 25°C DBT and 40% RH Discuss
Correct Answer: 22°C DBT and 60% RH
- 2. A low wet bulb temperature indicates very __________ humidity.
Options- A. low
- B. high Discuss
Correct Answer: low
- 3. A refrigerating system operating on reversed Brayton refrigeration cycle is used for maintaining 250 K. If the temperature at the end of constant pressure cooling is 300 K and rise in the temperature of air in the refrigerator is 50 K, then the net work of compression will be (assume air as working substance with cp = 1 kJ/kg)
Options- A. 25 kJ/kg
- B. 50 kJ/kg
- C. l00 kJ/kg
- D. 125 kJ/kg Discuss
Correct Answer: 50 kJ/kg
- 4. In chemical dehumidification process,
Options- A. dew point temperature decreases
- B. wet bulb temperature decreases
- C. dry bulb temperature increases
- D. all of these Discuss
Correct Answer: all of these
- 5. The highest temperature during the cycle in a vapour compression system occurs after evaporation.
Options- A. True
- B. False Discuss
Correct Answer: False
- 6. During dehumidification process, __________ remains constant.
Options- A. wet bulb temperature
- B. relative humidity
- C. dry bulb temperature
- D. specific humidity Discuss
Correct Answer: dry bulb temperature
- 7. In a psychrometric chart, dew point temperature lines are horizontal and non-uniformly spaced.
Options- A. Correct
- B. Incorrect Discuss
Correct Answer: Correct
- 8. A simple air cooling system is good for __________ flight speeds.
Options- A. low
- B. high Discuss
Correct Answer: low
- 9. Sulphur dioxide has the lowest boiling point.
Options- A. Yes
- B. No Discuss
Correct Answer: No
- 10. The lowest thermal diffusivity is of
Options- A. iron
- B. lead
- C. aluminium
- D. rubber Discuss
Correct Answer: rubber
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