Discussion
Home ‣ Mechanical Engineering ‣ Heat Transfer, Refrigeration and Air Conditioning Comments
- Question
The total radiation from a black body per second per unit area is __________ fourth power of the absolute temperature. This statement is known as Stefan-Boltzmann law.
Options- A. equal to
- B. directly proportional to
- C. inversely proportional to
- Correct Answer
- directly proportional to
- 1. In aqua-ammonia and Lithium-bromide water absorption refrigeration systems, the refrigerants are respectively
Options- A. water and water
- B. water and lithium bromide
- C. ammonia and lithium bromide
- D. ammonia and water Discuss
- 2. In a refrigerating machine, heat rejected is __________ heat absorbed.
Options- A. equal to
- B. less than
- C. greater than Discuss
- 3. 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
- 4. Nusselt number (NN) is given by
Options- A.
- B.
- C.
- D.
Discuss
- 5. The wet bulb temperature lines, on the psychrometric chart, are curved lines.
Options- A. True
- B. False Discuss
- 6. 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)
Options- A. Pb = pa - pv
- B. Pb = pa + pv
- C. Pb = pa x pv
- D. Pb = pa/pv Discuss
- 7. During a refrigeration cycle, heat is rejected by the refrigerant in a
Options- A. compressor
- B. condenser
- C. evaporator
- D. expansion valve Discuss
- 8. The critical radius is the insulation radius at which the resistance to heat flow is
Options- A. maximum
- B. minimum
- C. zero
- D. none of these Discuss
- 9. In free convection heat transfer transition from laminar to turbulent flow is governed by the critical value of the
Options- A. Reynold's number
- B. Grashoff's number
- C. Reynold's number, Grashoff's number
- D. Prandtl number, Grashoff's number Discuss
- 10. The humidity ratio or specific humidity is the mass of water vapour present in
Options- A. 1 m3 of wet air
- B. 1 m3 of dry air
- C. 1 kg of wet air
- D. 1 kg of dry air Discuss
Heat Transfer, Refrigeration and Air Conditioning problems
Search Results
Correct Answer: ammonia and water
Correct Answer: greater than
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
Correct Answer:
Correct Answer: False
Correct Answer: Pb = pa + pv
Correct Answer: condenser
Correct Answer: minimum
Correct Answer: Prandtl number, Grashoff's number
Correct Answer: 1 kg of dry air
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