There is no internal heat generation
Boundary surfaces are isothermal
Material is anisotropic
Constant temperature gradient exists
✅ The correct answer is option C.
Heat Transfer MCQs
Minimum recommended baffle spacing in a shell and tube heat exchanger is about (where, D = shell diameter)
0.2 D
0.5 D
0.66 D
0.80 D
✅ The correct answer is option A.
With increase in temperature, the thermal conductivity of a gas
Increases
Decreases
Remains same
May increase or decrease depending on the type of gas
✅ The correct answer is option A.
Which of the following is not used as a medium for high temperature heating?
Dowtherm
Mercury
Liquid metal (e.g. molten sodium)
Fused salts (e.g., an eutectic mixture of 53% KNO₃, 40% NaNO₂and 7% NaNO₃)
✅ The correct answer is option B.
Harmonic mean temperature difference is given by
√(ΔT₁ . ΔT₂)
2.(ΔT₁ . ΔT₂)/(ΔT₁ + ΔT₂)
2.(ΔT₁ . ΔT₂)(ΔT₁ – ΔT₂)
(ΔT₁ – ΔT₂)/(ΔT₁ . ΔT₂)
✅ The correct answer is option B.
In case of vertical tube evaporator, with increase in liquor level, the overall heat transfer co-efficient
Increases
Decreases
Is not affected
May increase or decrease; depends on the feed
✅ The correct answer is option B.
The actual temperature drop across the heating surface of an evaporator depends on the
Liquid depth over the heating surface
Solution being evaporated
Pressure difference between the steam chest and the vapor space above the boiling liquid
All of the above
✅ The correct answer is option D.
Which of the following has the lowest Prandtl number?
Molten sodium (a coolant used in fast breeder reactor)
Water
Transformer oil
Dilute H₂SO₄
✅ The correct answer is option A.
Reynold’s analogy states that (where, St = Stanton number f = friction factor)
St = f/2
St = f/4
St = 4f
St = f1/2
✅ The correct answer is option A.