Discussion
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- Question
An electric cable of aluminium conductor (k = 240 W/mK) is to be insulated with rubber (k = 0.15 W/mK). The cable is to be located in air (h = 6 W/m2). The critical thickness of insulation will be
Options- A. 25 mm
- B. 40 mm
- C. 160 mm
- D. 800 mm
- Correct Answer
- 25 mm
- 1. The heat rejection factor (HRF) is given by
Options- A. 1 + C.O.P
- B. 1 - C.O.P.
- C.
- D.
Discuss
- 2. Dew point temperature is the temperature of air recorded by a thermometer, when the moisture present in it begins to condense.
Options- A. Correct
- B. Incorrect Discuss
- 3. In a shell and tube heat exchanger, baffles are provided on the shell side to
Options- A. improve heat transfer
- B. provide support for tubes
- C. prevent stagnation of shell side fluid
- D. all of these Discuss
- 4. Fourier's law of heat conduction gives the heat flow for
Options- A. irregular surfaces
- B. non-uniform temperature surfaces
- C. one dimensional cases only
- D. two dimensional cases only Discuss
- 5. The condition of refrigerant after passing through the condenser in a vapour compression system is
Options- A. saturated liquid
- B. wet vapour
- C. dry saturated vapour
- D. superheated vapour Discuss
- 6. The amount of heat flow through a body by conduction is
Options- A. directly proportional to the surface area of the body
- B. directly proportional to the temperature difference on the two faces of the body
- C. inversely proportional to the thickness of the body
- D. all of the above Discuss
- 7. In order to collect liquid refrigerant and to prevent it from going to a __________ , a device known as accumulator is used at the suction of compressor.
Options- A. compressor
- B. condenser
- C. expansion valve
- D. evaporator Discuss
- 8. The dry bulb temperature during sensible heating of air
Options- A. remains constant
- B. increases
- C. decreases Discuss
- 9. A reversible engine has ideal thermal efficiency of 30%. When it is used as a refrigerating machine with all other conditions unchanged, the coefficient of performance will be
Options- A. 1.33
- B. 2.33
- C. 3.33
- D. 4.33 Discuss
- 10. In a vapour compression system, the condition of refrigerant is dry saturated vapour
Options- A. before entering the compressor
- B. after leaving the compressor
- C. before entering the condenser
- D. after leaving the condenser Discuss
Heat Transfer, Refrigeration and Air Conditioning problems
Search Results
Correct Answer:
Correct Answer: Correct
Correct Answer: all of these
Correct Answer: one dimensional cases only
Correct Answer: saturated liquid
Correct Answer: all of the above
Correct Answer: compressor
Correct Answer: increases
Correct Answer: 2.33
Correct Answer: before entering the compressor
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