Discussion
Home ‣ Mechanical Engineering ‣ Heat Transfer, Refrigeration and Air Conditioning Comments
- Question
The ratio of the thickness of thermal boundary layer to the thickness of hydrodynamic boundary layer is equal to (Prandtl number)n, where n is equal to
Options- A. -1/3
- B. -2/3
- C. 1
- D. -1
- Correct Answer
- -1/3
- 1. The use of heat exchangers is made in
Options- A. radiators in automobile
- B. condensers and boilers in steam plants
- C. condensers and evaporators in refrigeration and air conditioning units
- D. all of the above Discuss
- 2. For a white body, absorptivity (? ) = 0, reflectivity (?) = 1 and transmittivity (?) = 0.
Options- A. Correct
- B. Incorrect Discuss
- 3. For evaporators and condensers, for the given conditions, the logarithmic mean temperature difference (tm) for parallel flow is __________ that for counter flow.
Options- A. equal to
- B. less than
- C. greater than Discuss
- 4. The automobile radiator is a heat exchanger of
Options- A. parallel flow type
- B. counter flow type
- C. cross flow type
- D. regenerator type Discuss
- 5. The wave length corresponding to the maximum energy is inversely proportional to the absolute temperature. This statement is called Planck's law.
Options- A. Yes
- B. No Discuss
- 6. The sensible heat factor during the heating and humidification process is given by (where h1 = Enthalpy of air entering the heating coil, h2 = Enthalpy of air leaving the heating coil, and hA = Enthalpy of air at the end of humidification process)
Options- A.
- B.
- C.
- D.
Discuss
- 7. The horizontal and uniformly spaced lines on a psychrometric chart indicates relative humidity.
Options- A. Correct
- B. Incorrect Discuss
- 8. Bell-Coleman cycle is a
Options- A. reversed Carnot cycle
- B. reversed Otto cycle
- C. reversed Joule cycle
- D. reversed Rankine cycle Discuss
- 9. Which of the following statement is correct?
Options- A. A grey body is one which absorbs all radiations incident on it.
- B. At thermal equilibrium, the emissivity and absorptivity are same.
- C. The energy absorbed by a body to the total energy falling on it, is called emissivity.
- D. A perfect body is one which is black in colour. Discuss
- 10. The sulphur sticks, in case of leakage of ammonia refrigerant, gives white smoke.
Options- A. True
- B. False Discuss
Heat Transfer, Refrigeration and Air Conditioning problems
Search Results
Correct Answer: all of the above
Correct Answer: Correct
Correct Answer: equal to
Correct Answer: cross flow type
Correct Answer: No
Correct Answer:
Correct Answer: Incorrect
Correct Answer: reversed Joule cycle
Correct Answer: At thermal equilibrium, the emissivity and absorptivity are same.
Correct Answer: True
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