Discussion
Home ‣ Mechanical Engineering ‣ Heat Transfer, Refrigeration and Air Conditioning Comments
- Question
According to Prevost's theory of exchanges, every body irrespective of its temperature continuously emit heat radiations to the surrounding bodies and at the same time receives heat radiations from the surrounding bodies.
Options- A. True
- B. False
- Correct Answer
- True
- 1. The thermostatic expansion valve operates on the changes in the
Options- A. degree of superheat at exit from the evaporator
- B. temperature of the evaporator
- C. pressure in the evaporator
- D. none of the above Discuss
- 2. The C.O.P. of a Carnot refrigerator in winter will be __________ as compared to C.O.P. in summer.
Options- A. same
- B. lower
- C. higher Discuss
- 3. The super-heating in a refrigeration cycle
Options- A. does not alter C.O.P.
- B. increases C.O.P.
- C. decreases C.O.P.
- D. none of these Discuss
- 4. The operating pressure for refrigerating units using R-12 as a refrigerant is
Options- A. 2 bar
- B. 8 bar
- C. 15 bar
- D. 30 bar Discuss
- 5. The boiling point of __________ is -10.5°C.
Options- A. ammonia
- B. R-12
- C. sulphur dioxide
- D. carbon dioxide Discuss
- 6. The superheated vapour region, in a pressure enthalpy chart, is represented by the space
Options- A. to the left of saturated liquid line
- B. to the right of saturated liquid line
- C. between the saturated liquid line and saturated vapour line
- D. none of the above Discuss
- 7. In a saturated air-water vapour mixture, the
Options- A. dry bulb temperature is higher than wet bulb temperature
- B. dew point temperature is lower than wet bulb temperature
- C. dry bulb, wet bulb and dew point temperature are same
- D. dry bulb temperature is higher than dew point temperature Discuss
- 8. The freezing point of R-12 is
Options- A. -86.6°C
- B. -95.2°C
- C. -107.7°C
- D. -135.8°C Discuss
- 9. The capillary tube is not used in large capacity refrigeration systems because
Options- A. cost is too high
- B. capacity control is not possible
- C. it is made of copper
- D. required pressure drop can not be achieved Discuss
- 10. The thermal diffusivity for gases is generally __________ those for liquids.
Options- A. equal to
- B. less than
- C. greater than Discuss
Heat Transfer, Refrigeration and Air Conditioning problems
Search Results
Correct Answer: degree of superheat at exit from the evaporator
Correct Answer: higher
Correct Answer: decreases C.O.P.
Correct Answer: 8 bar
Correct Answer: sulphur dioxide
Correct Answer: between the saturated liquid line and saturated vapour line
Correct Answer: dry bulb, wet bulb and dew point temperature are same
Correct Answer: -135.8°C
Correct Answer: capacity control is not possible
Correct Answer: greater than
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