Discussion
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- Question
Economy of a multiple effect evaporator is not influenced much by the
Options- A. boiling point elevations
- B. temperature of the feed
- C. rate of heat transfer
- D. ratio of the weight of the thin liquor to thick liquor
- Correct Answer
- boiling point elevations
- 1. Thermal conductivity of a conducting solid material depends upon its
Options- A. temperature
- B. porosity
- C. both (a) & (b)
- D. neither (a) nor (b) Discuss
- 2. Steam consumption in kg/hr in case of an evaporator is given by (where, C & E are capacity the economy of the evaporator respectively)
Options- A. C/E
- B. E/C
- C. CE
- D.
Discuss
- 3. The thermal efficiency of a reversible heat engine operating between two given thermal reservoirs is 0.4. The device is used either as a refrigerator or as a heat pump between the same reservoirs. Then the coefficient of performance as a refrigerator (COP)R and the co-efficient of performance as a heat pump (COP)HP are
Options- A. (COP)R = (COP)HP = 0.6
- B. (COP)R = 2.5; (COP)HP = 1.5
- C. (COP)R = 1.5; (COP)HP = 2.5
- D. (COP)R = (COP)HP = 2.5 Discuss
- 4. Pick out the wrong statement.
Options- A. In case of heat transfer by purely forced convection, GR/Re2 ? 1.
- B. The equivalent diameter of heat transfer for a duct of square cross-section (having each side as 'x') is equal to 4x.
- C. Distillation process is not the same as evaporation.
- D. The effectiveness of nucleate boiling depends basically on the ease with which the bubbles are formed and detached from the heating surface. Discuss
- 5. A backward feed multiple effect evaporator is better than forward feed for concentrating cold feed, because it provides
Options- A. higher economy
- B. lower capacity
- C. both (a) & (b)
- D. lower economy Discuss
- 6. For shell and tube heat exchanger, with increasing heat transfer area, the purchased cost per unit heat transfer area
Options- A. increases
- B. decreases
- C. remains constant
- D. passes through a maxima Discuss
- 7. Bulk of the convective heat transfer resistance from a hot tube surface to the fluid flowing in it, is
Options- A. in the central core of the fluid.
- B. uniformly distributed throughout the fluid.
- C. mainly confined to a thin film of fluid near the surface.
- D. none of these. Discuss
- 8. Baffles in the shell side of a shell and tube heat exchanger
Options- A. increase the cross-section of the shell side liquid.
- B. force the liquid to flow parallel to the bank.
- C. increase the shell side heat transfer co-efficient.
- D. decrease the shell side heat transfer co-efficient. Discuss
- 9. The actual temperature drop across the heating surface in an evaporator depends on the
Options- A. feed.
- B. depth of liquid over heating surface.
- C. pressure difference between steam chest and vapour space.
- D. all (a), (b) and (c). Discuss
- 10. Air is to be heated by condensing steam. Two heat exchangers are available (i) a shell and tube heat exchanger and (ii) a finned tube heat exchanger. Tube side heat transfer area are equal in both the cases. The recommended arrangement is
Options- A. finned tube heat exchanger with air inside and steam outside.
- B. finned tube heat exchanger with air outside and steam inside.
- C. shell and tube heat exchanger with air inside tubes and steam on shell side.
- D. shell and tube heat exchanger with air on shell side and steam inside tubes. Discuss
Heat Transfer problems
Search Results
Correct Answer: both (a) & (b)
Correct Answer: C/E
Correct Answer: (COP)R = 1.5; (COP)HP = 2.5
Correct Answer: The equivalent diameter of heat transfer for a duct of square cross-section (having each side as 'x') is equal to 4x.
Correct Answer: higher economy
Correct Answer: passes through a maxima
Correct Answer: mainly confined to a thin film of fluid near the surface.
Correct Answer: increase the shell side heat transfer co-efficient.
Correct Answer: all (a), (b) and (c).
Correct Answer: finned tube heat exchanger with air outside and steam inside.
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