1. 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.
Heat Transfer MCQs
2. 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.
3. 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.
4. The ratio of kinematic viscosity to thermal diffusivity is called the __________ number.
Peclet
Prandtl
Stanton
Nusselt
✅ The correct answer is option B.
5. 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.
6. (NGr x NPr) is called the __________ number.
Graetz
Reyleigh
Nusselt
Stanton
✅ The correct answer is option B.
7. The rate of emission of radiation by a body does not depend upon the
Wavelength of radiation
Surface temperature of the body
Nature of the surface
Shape and porosity of the body
✅ The correct answer is option D.
8. Heat flux increases with temperature drop beyond the Leiden frost point in the plot of heat flux vs. temperature drop for a boiling liquid, because
Convection becomes important
Conduction becomes important
Radiation becomes important
Sub-cooled boiling occurs
✅ The correct answer is option C.
9. Crystal size in a continuous crystalliser depends upon the
Rate of heat transfer
Degree of turbulence
Degree of supersaturation
All of the above
✅ The correct answer is option D.
10. Loss of heat from untagged steam pipe to the ambient air is by
Conduction
Convection
Radiation
All of the above
✅ The correct answer is option D.