401. The most conducive surface for dropwise condensation to occur is the __________ surface.
Coated
Oily
Glazed & polished
Smooth
✅ The correct answer is option B.
Heat Transfer MCQs
402. Which of the following has the minimum thermal conductivity?
Nitrogen
Steel
Carbon black
Tar
✅ The correct answer is option A.
403. Kirchoff’s law is applicable to
Monochromatic radiation only
Total radiation only
Both A and B
Only volumes and not to surfaces
✅ The correct answer is option C.
404. Nusselt number (for forced convection heat transfer) is a function of the __________ number.
Prandtl
Reynolds
Both A & B
Neither A nor B
✅ The correct answer is option C.
405. Maximum water velocity in tubes of a 1-2 shell and tube heat exchanger may be around __________ metres/second.
1
10
20
30
✅ The correct answer is option A.
406. The equation, (NSt x N2/3Pr) = f/2, is the __________ analogy.
Colburn
Reynolds
Prandtl
None of these
✅ The correct answer is option A.
407. For condensation of pure vapors, if the heat transfer co-efficients in filmwise and drop-wise condensation are respectively hf and hd, then
hf = hd
hf > hd
hf < hd
hf could be greater or smaller than hd
✅ The correct answer is option C.
408. An equipment which converts the latent or sensible heat of one fluid into the latent heat of vaporisation of another, is called a
Boiler
Heat exchanger
Recuperator
Regenerator
✅ The correct answer is option B.
409. Thermal conductivity of a gas at low density, __________ with increase in temperature.
Decreases
Increases
Remains unchanged
May increase or decrease; depends on the gas
✅ The correct answer is option B.
410. The equation, Nst = f/2, is the __________ analogy.
Colburn
Reynolds
Prandtl
None of these
✅ The correct answer is option B.