241. The wavelength at which the maximum monochromatic emissive power occurs for a black body, is (where, T = absolute temperature of the black body)
αT
α 1/T
α T⁴
Independent of T
✅ The correct answer is option B.
Heat Transfer MCQs
242. The thickness of condensate layer in filmwise condensation depends on the
Condensation rate
Surface configuration
Liquid flow rate from the surface
All of the above
✅ The correct answer is option D.
243. ‘Fouling factor’ used in the design of a multipass shell and tube heat exchanger is a
Non-dimensional factor
Factor of safety
Conversion factor for individual film heat transfer co-efficient to overall heat transfer co-efficient
None of these
✅ The correct answer is option B.
244. In forced convection, the heat transfer depends on
Re, Pr
Re, Gr
Mainly Gr
Re only
✅ The correct answer is option A.
245. For hot feed, forward feeding as compared to backward feeding results in __________ economy.
Increased
Decreased
No effect on
None of these
✅ The correct answer is option A.
246. Prandtl and Reynolds analogy are same, when Prandtl number is
0.5
1
> 2
1.5
✅ The correct answer is option B.
247. Log mean temperature difference (LMTD) cannot be used, if
Heat transfer co-efficient over the entire heat exchanger is not constant
There exists an unsteady state
The heat capacity is not constant and there is a phase change
None of these
✅ The correct answer is option D.
248. In a shell and tube heat exchanger,
The temperature drops in the two fluids and the wall are proportional to individual resistances
The temperature drop is inversely proportional to the resistance across which the drop occurs
There is no relationship between temperature drop and resistance
The relationship is not generalised
✅ The correct answer is option A.
249. Steam is routed through the tube in case of a __________ evaporator.
Basket type
Horizontal tube
Short tube vertical
Long tube vertical
✅ The correct answer is option B.
250. In a single evaporator system, the steam economy __________ by creating vacuum in the evaporator.
Increases
Decreases
Remains constant
May increase or decrease, depends on the vacuum
✅ The correct answer is option A.