Increasing temperature of the vapour
Decreasing temperature of the vapour
Increasing viscosity of the film of condensate
Increasing temperature drop
✅ The correct answer is option A.
Heat Transfer MCQs
32. Tube expansion allowances exist in __________ heat exchanger.
Multipass fixed tube sheet
U-tube
Single pass fixed tube sheet
None of these
✅ The correct answer is option B.
33. The maximum heat transfer co-efficient from steam heating will be attained when the steam is
Supersaturated
Saturated
Wet
None of these
✅ The correct answer is option B.
34. For heat flow through very thick walled cylinder, use____mean radius.
Arithmetic
Logarithmic
Geometric
Either A or C
✅ The correct answer is option B.
35. Which of the following is concerned with both heat and mass transfer?
Lewis relationship
Nusselt number
Kutateladze number
Froude number
✅ The correct answer is option A.
36. Economy of a multiple effect evaporator is not influenced much by the
Boiling point elevations
Temperature of the feed
Rate of heat transfer
Ratio of the weight of the thin liquor to thick liquor
✅ The correct answer is option A.
37. Double pipe heat exchangers are used
When heat transfer area required is very high
When heat transfer area required is very low, i.e (100-200 ft²)
Because it occupies less floor area
Because it is less costly
✅ The correct answer is option B.
38. A fluid is flowing inside the inner tube of a double pipe heat exchanger with diameter ‘d’. For a fixed mass flow rate, the tube side heat transfer co-efficient for turbulent flow conditions is proportional to
D0.8
D-0.2
D-1
D-1.8
✅ The correct answer is option B.
39. Boiling point elevation for a strong and concentrated solution is found by Duhring’s rule, which states that at the same pressure, the boiling point of a solution is a linear function of the __________ of pure water.
Boiling point
Dynamic viscosity
Kinematic viscosity
Density
✅ The correct answer is option A.
40. In evaporators, lowering the feed temperature
Increases the heating area required
Reduces the economy
Both A and B
Decreases the heating area required
✅ The correct answer is option C.