Facilitate the cleaning of outer tube surface
Enhance turbulence
Hold the tubes in position
All of the above
✅ The correct answer is option B.
Heat Transfer MCQs
Overall heat transfer co-efficient of a particular tube is U₁. If the same tube with some dirt deposited on either side has coefficient U₂, then
U₁ = U₂
U₂ > U₁
U₁ > U₂
U₁ = dirt factor – U₂
✅ The correct answer is option A.
What is the thermal conductivity of a perfect heat insulator?
Zero
One
∞
Between 0 and ∞
✅ The correct answer is option A.
Which of the following is correct?
Rate = Driving force x Resistance
Driving force = Rate x Resistance
Resistance = Driving force x Rate
Rate = Resistance/Driving force
✅ The correct answer is option B.
In a shell and tube heat exchanger, the height of 25 percent cut baffles is equal to (where, D = inside diameter of shell)
0.25 D
0.75 D
0.50 D
None of these
✅ The correct answer is option B.
LMTD for evaporators & condensers for a given terminal parameters & set of conditions for counterflow is equal to that for parallel flow. In such heat exchangers, with one of the fluids condensing or evaporating, the surface area required is the least in the __________ flow.
Parallel
Mixed
Counterflow
Same in either A, B or C
✅ The correct answer is option D.
Latent heat absorbed by 1 lb of water at 212°F, when it is changed to steam at 212°F, may be around __________ BTU.
180
970
3.97
None of these
✅ The correct answer is option A.
The ratio of kinematic viscosity to thermal diffusivity is called the __________ number.
Peclet
Prandtl
Stanton
Nusselt
✅ The correct answer is option B.
In case of a shell and tube heat exchanger, the minimum and maximum baffle spacing is respectively (where, D = inside diameter of the shell)
D/5 and D
D/2 and 2 D
D/4 and 2 D
D and 2 D
✅ The correct answer is option A.
(NGr x NPr) is called the __________ number.
Graetz
Reyleigh
Nusselt
Stanton
✅ The correct answer is option B.