251. The Nusselt number for fully developed (both thermally and hydrodynamically) laminar flow through a circular pipe, where the wall heat flux is constant, is
2.36
4.36
120.36
Dependent on NRe only
✅ The correct answer is option B.
Heat Transfer MCQs
252. A multiple effect evaporator has a capacity to process 4000 kg of solid caustic soda per day, when it is concentrating from 10% to 25% solids. The water evaporated in kg per day is
6000
24000
60000
48000
✅ The correct answer is option B.
253. Steam trap is used to
Condense the steam flowing in the pipeline
Remove water resulting from partial condensation of steam
Stop the supply of steam
None of these
✅ The correct answer is option B.
254. In a backward feed multiple effect evaporator
Feed is introduced in the first effect
Feed flows from low pressure to high pressure
No pumps are required between successive effects
None of these
✅ The correct answer is option B.
255. The Grashoff number is defined as the ratio of the
Buoyancy to inertial forces
Buoyancy to viscous forces
Inertial to viscous forces
Buoyancy to surface tension forces
✅ The correct answer is option B.
256. Electromagnetic radiations propagate in vacuum with a velocity of __________ metre/second.
3 x l05
3 x l08
3 x l010
3 x l012
✅ The correct answer is option B.
257. Vibrations in the tubes of a shell and tube heat exchanger is induced due to the
Flow of fluid on the tube and shell sides
Oscillations in the flow of shell/tube sides fluid
Vibrations transmitted through piping and/or supports due to external reasons
All of the above
✅ The correct answer is option D.
258. The energy radiated from a surface Q at absolute temperature T is related as
Q ∝ T²
Q ∝ T⁴
Q ∝ T³
None of these
✅ The correct answer is option B.
259. All analogy equations connecting friction factor and heat transfer co-efficient apply only to
Wall or skin friction
Form friction
Both A and B
Turbulent flow
✅ The correct answer is option A.
260. Which one gives the monochromatic emissive power for black body radiation?
Planck’s law
Kirchhoffs law
Wien’s law
Stefan-Boltzman law
✅ The correct answer is option A.