Heat Transfer, Refrigeration and Air Conditioning problems
- 1. The sensible heat factor during cooling and dehumidification process is given by (where h1 = Enthalpy of air entering the cooling coil, h2 = Enthalpy of air leaving the cooling coil, and hA = Enthalpy of air at the end of dehumidification process)
Options- A.
- B.
- C.
- D.
Discuss
Correct Answer:
- 2. The optimum effective temperature for human comfort is
Options- A. higher in winter than in summer
- B. lower in winter than in summer
- C. same in winter and summer
- D. not dependent on season Discuss
Correct Answer: lower in winter than in summer
- 3. Defrosting of a refrigerator may be done by stopping the compressor for a short period.
Options- A. Correct
- B. Incorrect Discuss
Correct Answer: Correct
- 4. A water cooled condenser operates at a __________ condensing temperature than an air-cooled condenser.
Options- A. higher
- B. lower Discuss
Correct Answer: lower
- 5. For ammonia refrigerating systems, the tubes of a shell and tube condenser are made of
Options- A. copper
- B. aluminium
- C. steel
- D. brass Discuss
Correct Answer: steel
- 6. In a psychrometric process, the sensible heat added is 30 kJ/s and the latent heat added is 20 kJ/s. The sensible heat factor for the process will be
Options- A. 0.3
- B. 0.6
- C. 0.67
- D. 1.5 Discuss
Correct Answer: 0.6
- 7. The heat transfer by conduction through a thick sphere is same as through a thick cylinder.
Options- A. True
- B. False Discuss
Correct Answer: False
- 8. As relative humidity decreases, the dew point temperature will be __________ wet bulb temperature.
Options- A. same as
- B. lower than
- C. higher man Discuss
Correct Answer: lower than
- 9. Which of the following statement is wrong?
Options- A. The heat transfer in liquid and gases takes place according to convection.
- B. The amount of heat flow through a body is dependent upon the material of the body.
- C. The thermal conductivity of solid metals increases with rise in temperature,
- D. Logarithmic mean temperature difference is not equal to the arithmetic mean temperature difference. Discuss
Correct Answer: The thermal conductivity of solid metals increases with rise in temperature,
- 10. During adiabatic saturation process on unsaturated air __________ remains constant.
Options- A. relative humidity
- B. dew point temperature
- C. dry bulb temperature
- D. wet bulb temperature Discuss
Correct Answer: wet bulb temperature
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