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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.

Answer

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

Answer

Correct Answer: 70 to 110° C

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20. The highest thermal diffusivity is of

Answer

Correct Answer: Lead

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21. The optimum effective temperature for human comfort is

Answer

Correct Answer: Lower in winter than in summer

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