Heat Transfer, Refrigeration and Air Conditioning problems
- 1. The centrifugal compressors are generally used for refrigerants that require
Options- A. small displacements and low condensing pressures
- B. large displacements and high condensing pressures
- C. small displacements and high condensing pressures
- D. large displacements and low condensing pressures Discuss
Correct Answer: large displacements and low condensing pressures
- 2. A heat exchanger with heat transfer surface area A and overall heat transfer coefficient U handles two fluids of heat capacities Cmax and Cmin. The number of transfer units (NTU) used in the analysis of heat exchanger is specified as
Options- A.
- B.
- C. AU Cmin
- D.
Discuss
Correct Answer:
- 3. Which of the following statement is correct for ammonia as a refrigerant?
Options- A. It is toxic to mucous membranes.
- B. it requires large displacement per TR compared to fluoro carbons.
- C. It reacts with copper and its alloys.
- D. all of these Discuss
Correct Answer: all of these
- 4. During humidification process, __________ increases.
Options- A. wet bulb temperature
- B. relative humidity
- C. dry bulb temperature
- D. specific humidity Discuss
Correct Answer: relative humidity
- 5. Conduction is a process of heat transfer
Options- A. from one particle of the body to another without the actual motion of the particles
- B. from one particle of the body to another by the actual motion of the heated particles.
- C. from a hot body to a cold body, in a straight line, without affecting the intervening medium
- D. none of the above Discuss
Correct Answer: from one particle of the body to another without the actual motion of the particles
- 6. Sulphur dioxide is extremely toxic and non-flammable.
Options- A. True
- B. False Discuss
Correct Answer: True
- 7. A heat pump working on a reversed Carnot cycle has a C.O.P. of 5. It works as a refrigerator taking 1 kW of work input. The refrigerating effect will be
Options- A. 1 kW
- B. 2 kW
- C. 3 kW
- D. 4 kW Discuss
Correct Answer: 4 kW
- 8. The emissivity for a black body is
Options- A. 0
- B. 0.5
- C. 0.75
- D. 1 Discuss
Correct Answer: 1
- 9. Thermal conductivity of air increases with rise in temperature.
Options- A. Correct
- B. Incorrect Discuss
Correct Answer: Correct
- 10. In a heat exchanger with one fluid evaporating or condensing, the surface area required is least in
Options- A. parallel flow
- B. counter flow
- C. cross flow
- D. all of these Discuss
Correct Answer: all of these
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