Heat Transfer, Refrigeration and Air Conditioning problems
- 1. 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 Discuss
Correct Answer: True
- 2. 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
Correct Answer: between the saturated liquid line and saturated vapour line
- 3. 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
Correct Answer: dry bulb, wet bulb and dew point temperature are same
- 4. 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
Correct Answer: -135.8°C
- 5. 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
Correct Answer: capacity control is not possible
- 6. The thermal diffusivity for gases is generally __________ those for liquids.
Options- A. equal to
- B. less than
- C. greater than Discuss
Correct Answer: greater than
- 7. The alignment circle is marked on the psychrometric chart at
Options- A. 20°C DBT and 50% RH
- B. 26°C DBT and 50% RH
- C. 20°C DBT and 60% RH
- D. 26°C DBT and 60% RH Discuss
Correct Answer: 26°C DBT and 50% RH
- 8. One tonne of refrigeration (1TR) means that the heat removing capacity is
Options- A. 21 kJ/min
- B. 210 kJ/min
- C. 420 kJ/min
- D. 620 kJ/min Discuss
Correct Answer: 210 kJ/min
- 9. The freezing point of carbon dioxide is equal to boiling point of R-12.
Options- A. Correct
- B. Incorrect Discuss
Correct Answer: Incorrect
- 10. According to Stefan-Boltzmann law, the total radiation from a black body per second per unit area is directly proportional to the
Options- A. absolute temperature
- B. square of the absolute temperature
- C. cube of the absolute temperature
- D. fourth power of the absolute temperature Discuss
Correct Answer: fourth power of the absolute temperature
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