Discussion
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- Question
The average heat transfer co-efficient for laminar film condensation on vertical surface is inversely proportional to (where, ?T = Temperature drop across condensate film )
Options- A. (?T)2
- B. ?T
- C. (?T)1/4
- D. (?T)3/2
- Correct Answer
- (?T)1/4
- 1. Increasing the liquor level in the evaporator results in the
Options- A. decreased capacity.
- B. increase in liquor film co-efficient.
- C. decreased effect of hydrostatic head.
- D. increased true temperature drop. Discuss
- 2. Convective heat transfer co-efficient in case of fluid flowing in tubes is not affected by the tube length/diameter ratio, if the flow is in the __________ zone.
Options- A. laminar
- B. transition
- C. both 'a' & 'b'
- D. highly turbulent Discuss
- 3. Which of the following is not used as a medium for high temperature heating?
Options- A. Dowtherm
- B. mercury
- C. liquid metal (e.g. molten sodium)
- D. fused salts (e.g., an eutectic mixture of 53% KNO3, 40% NaNO2and 7% NaNO3) Discuss
- 4. Presence of a non-condensing gas in a condensing vapour
Options- A. increases the rate of condensation.
- B. decreases thermal resistance.
- C. is desirable to increase the film co-efficient.
- D. none of these. Discuss
- 5. Heat waves
Options- A. can not pass through vacuum.
- B. travel in straight line.
- C. can be reflected by a mirror.
- D. both (b) and (c). Discuss
- 6. In case of evaporators, liquid entrainment results primarily due to
Options- A. high vacuum in the evaporator.
- B. high evaporation rate.
- C. foaming of the solution.
- D. high heat transfer rate. Discuss
- 7. 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
- 8. 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
- 9. 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
- 10. 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
Heat Transfer problems
Search Results
Correct Answer: decreased capacity.
Correct Answer: highly turbulent
Correct Answer: mercury
Correct Answer: none of these.
Correct Answer: both (b) and (c).
Correct Answer: foaming of the solution.
Correct Answer: higher economy
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: (COP)R = 1.5; (COP)HP = 2.5
Correct Answer: C/E
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