Heat Transfer, Refrigeration and Air Conditioning problems
- 1. Reynolds number (RN) is given by (where h = Film coefficient, l = Linear dimension, V = Velocity of fluid, k = Thermal conductivity, t = Temperature, ? = Density of fluid, cp = Specific heat at constant pressure, and ? = Coefficient of absolute viscosity)
Options- A.
- B.
- C.
- D.
Discuss
Correct Answer:
- 2. Thermal conductivity of water __________ with rise in temperature.
Options- A. remains same
- B. decreases
- C. increases
- D. may increase or decrease depending upon temperature Discuss
Correct Answer: may increase or decrease depending upon temperature
- 3. A refrigeration system
Options- A. removes heat from a low temperature body and delivers it to a high temperature body
- B. removes heat from a high temperature body and delivers it to a low temperature body
- C. rejects energy to a low temperature body
- D. none of the above Discuss
Correct Answer: removes heat from a low temperature body and delivers it to a high temperature body
- 4. A perfect black body is one which
Options- A. is black in colour
- B. absorbs heat radiations of all wave lengths falling on it
- C. reflects all the heat radiations
- D. transmits the heat radiations Discuss
Correct Answer: absorbs heat radiations of all wave lengths falling on it
- 5. While designing the refrigeration system of an aircraft, the prime consideration is that the
Options- A. system has high C.O.P.
- B. power per TR is low
- C. mass of refrigerant circulated in the system is low
- D. mass of the refrigeration equipment is low Discuss
Correct Answer: mass of the refrigeration equipment is low
- 6. The difference between dry bulb temperature and wet bulb temperature, is called
Options- A. dry bulb depression
- B. wet bulb depression
- C. dew point depression
- D. degree of saturation Discuss
Correct Answer: wet bulb depression
- 7. The wet bulb temperature lines, on the psychrometric chart, are curved lines.
Options- A. True
- B. False Discuss
Correct Answer: False
- 8. Nusselt number (NN) is given by
Options- A.
- B.
- C.
- D.
Discuss
Correct Answer:
- 9. The relative humidity is defined as
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 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
- 10. In a refrigerating machine, heat rejected is __________ heat absorbed.
Options- A. equal to
- B. less than
- C. greater than Discuss
Correct Answer: greater than
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