Heat Transfer, Refrigeration and Air Conditioning MCQ
Heat Transfer, Refrigeration and Air Conditioning MCQ
1. The process of ________ involves the movement or circulation of a mass or substance.
Answer
Correct Answer:
Convection
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2. A heat pump working on a reversed Carnot cycle has a C.O.P. of 5. It works as a refrigerator taking 1 kW of work input. The refrigerating effect will be
Answer
Correct Answer:
4 kW
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3. During humidification process, __________ increases.
Answer
Correct Answer:
Relative humidity
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4. The relative humidity is defined as
Answer
Correct Answer:
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
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5. The difference between dry bulb temperature and wet bulb temperature, is called
Answer
Correct Answer:
Wet bulb depression
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6. A pressure gauge on the discharge side of a refrigerant compressor reads too high. The reasons will be
Answer
Correct Answer:
All of these
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7. Thermal diffusivity is a
Answer
Correct Answer:
Physical property of a substance
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8. The centrifugal compressors are generally used for refrigerants that require
Answer
Correct Answer:
Large displacements and low condensing pressures
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9. In aqua-ammonia and Lithium-bromide water absorption refrigeration systems, the refrigerants are respectively
Answer
Correct Answer:
Ammonia and water
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10. According to Dalton's law of partial pressures, (where pb = Barometric pressure, pa = Partial pressure of dry air, and pv = Partial pressure of water vapour)
Answer
Correct Answer:
Pb = pa + pv
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11. During sensible cooling of air __________ decreases.
Answer
Correct Answer:
Dry bulb temperature
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12. The water, alcohol and ammonia have same refrigerating effect at different altitudes.
Answer
Correct Answer:
No
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13. In a refrigerating machine, heat rejected is __________ heat absorbed.
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Correct Answer:
Greater than
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14. The subcooling in a refrigeration cycle
Answer
Correct Answer:
Increases C.O.P.
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15. In case of solids, the heat transfer takes place according to radiation.
Answer
Correct Answer:
Incorrect
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16. Degree of saturation or percentage humidity is
Answer
Correct Answer:
The ratio of the actual mass of water vapour in a unit mass of dry air to the mass of water vapour in the same mass of dry air when it is saturated at the same temperature and pressure.
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17. An electrolux refrigerator is called a __________ absorption system.
Answer
Correct Answer:
Three fluids
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18. The wet bulb temperature during sensible heating of air
Answer
Correct Answer:
Increases
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19. The temperature of ammonia after compression in a vapour compression system is
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Correct Answer:
70 to 110° C
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20. The highest thermal diffusivity is of
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Correct Answer:
Lead
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21. The optimum effective temperature for human comfort is
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Correct Answer:
Lower in winter than in summer
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