Discussion
Home ‣ Mechanical Engineering ‣ Heat Transfer, Refrigeration and Air Conditioning Comments
- Question
In mechanical refrigeration system, the refrigerant has the maximum temperature
Options- A. in evaporator
- B. before expansion valve
- C. between compressor and condenser
- D. between condenser and evaporator
- Correct Answer
- between compressor and condenser
- 1. In a reversed Brayton cycle, the heat is absorbed by the air during
Options- A. isentropic compression process
- B. constant pressure cooling process
- C. isentropic expansion process
- D. constant pressure expansion process Discuss
- 2. The coefficient of performance (C.O.P.) of a refrigerator working as a heat pump is given by
Options- A. (C.O.P.)P = (C.O.P.)R + 2
- B. (C.O.P.)P = (C.O.P.)R + 1
- C. (C.O.P)P = (C.O.P)R - 1
- D. (C.O.P)P = (C.O.P)R Discuss
- 3. Film coefficient is defined as the ratio of
Options- A. thermal conductivity to the equivalent thickness of the film of fluid
- B. temperature drop through the films of fluids to the thickness of film of fluids
- C. thickness of film of fluid to the thermal conductivity
- D. thickness of film of fluid to the temperature drop through the films of fluids Discuss
- 4. Kirchhoff's law states that
Options- A. the total radiation from a black body per second per unit area is directly proportional to the fourth power of the absolute temperature
- B. the wave length corresponding to the maximum energy is proportional to the absolute temperature
- C. the ratio of the emissive power and absorptive power of all bodies is the same and is equal to the emissive power of a perfectly black body
- D. none of the above Discuss
- 5. Which of the following statement is wrong?
Options- A. The value of C.O.P. is always greater than one.
- B. In a vapour compression system, the condition of refrigerant before entering the compressor is dry saturated vapour.
- C. The space between the saturated liquid line and saturated vapour line, in a pressure enthalpy chart, is wet vapour region.
- D. none of the above Discuss
- 6. Moisture should be removed from refrigerants to avoid
Options- A. freezing at the expansion valve
- B. restriction to refrigerant flow
- C. corrosion of steel plates
- D. all of these Discuss
- 7. In air-conditioning of aeroplanes, using air as a refrigerant, the cycle used is
Options- A. reversed Carnot cycle
- B. reversed Joule cycle
- C. reversed Brayton cycle
- D. reversed Otto cycle Discuss
- 8. The critical thickness of insulation for a sphere is
Options- A. k/h0
- B. 2k/h0
- C. h0/k
- D. h0/2k Discuss
- 9. The ratio of surface convection resistance to the internal conduction resistance is known as
Options- A. Grashoff number
- B. Biot number
- C. Stanton number
- D. Prandtl number Discuss
- 10. Wet bulb temperature is the temperature of air recorded by a thermometer, when
Options- A. it is not effected by the moisture present in the air
- B. its bulb is surrounded by a wet cloth exposed to the air
- C. the moisture present in it begins to condense
- D. none of the above Discuss
Heat Transfer, Refrigeration and Air Conditioning problems
Search Results
Correct Answer: constant pressure expansion process
Correct Answer: (C.O.P.)P = (C.O.P.)R + 1
Correct Answer: thermal conductivity to the equivalent thickness of the film of fluid
Correct Answer: the ratio of the emissive power and absorptive power of all bodies is the same and is equal to the emissive power of a perfectly black body
Correct Answer: none of the above
Correct Answer: all of these
Correct Answer: reversed Brayton cycle
Correct Answer: 2k/h0
Correct Answer: Biot number
Correct Answer: its bulb is surrounded by a wet cloth exposed to the air
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