Heat Transfer, Refrigeration and Air Conditioning problems
- 1. The heat transfer takes place according to
Options- A. Zeroth law of thermodynamics
- B. First law of thermodynamics
- C. Second law of thermodynamics
- D. Kirchhoff's law Discuss
Correct Answer: Second law of thermodynamics
- 2. The amount of radiation mainly depends upon the
Options- A. nature of the body
- B. temperature of the body
- C. type of surface of the body
- D. all of these Discuss
Correct Answer: all of these
- 3. The temperature of ammonia after compression in a vapour compression system is
Options- A. 20 to 50° C
- B. 50 to 70° C
- C. 70 to 110° C
- D. none of these Discuss
Correct Answer: 70 to 110° C
- 4. The coefficient of performance of Heat Pump is always __________ one.
Options- A. equal to
- B. less than
- C. greater than Discuss
Correct Answer: greater than
- 5. Degree of saturation or percentage humidity is
Options- A. the mass of water vapour present in 1 m3 of dry air
- B. the mass of water vapour present in 1 kg of dry air
- C. 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.
- D. 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 Discuss
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.
- 6. The subcooling in a refrigeration cycle
Options- A. does not alter C.O.P.
- B. increases C.O.P.
- C. decreases C.O.P.
- D. none of these Discuss
Correct Answer: increases C.O.P.
- 7. Fourier's law of heat conduction is (where Q = Amount of heat flow through the body in unit time, A = Surface area of heat flow, taken at right angles to the direction of heat flow, dT = Temperature difference on the two faces of the body, dx = Thickness of the body, through which the heat flows, taken along the direction of heat flow, and k = Thermal conductivity of the body)
Options- A.
- B.
- C.
- D.
Discuss
Correct Answer:
- 8. The process of heat transfer from a hot body to a cold body, in a straight line, without affecting the intervening medium, is called radiation.
Options- A. True
- B. False Discuss
Correct Answer: True
- 9. The by-pass factor for a cooling coil
Options- A. increases with increase in velocity of air passing through it
- B. decreases with increase in velocity of air passing through it
- C. remains unchanged with increase in velocity of air passing through it
- D. may increase or decrease with increase in velocity of air passing through it depending upon the condition of air entering Discuss
Correct Answer: increases with increase in velocity of air passing through it
- 10. The formation of frost on cooling coils in a refrigerator
Options- A. increases heat transfer
- B. improves C.O.P. of the system
- C. increases power consumption
- D. reduces power consumption Discuss
Correct Answer: increases power consumption
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