391. Conduction occurs in the buffer zone for a fluid flowing through a heated pipe, only when Prandtl number is
0.1
>1
< 1
L
✅ The correct answer is option A.
Heat Transfer MCQs
392. __________ heat exchanger is the most suitable, when the temperature of shell side fluid is much higher than that of tube side.
Single pass, fixed tube sheet
U-tube
Three pass, fixed tube sheet
None of these
✅ The correct answer is option B.
393. Agitated film evaporator is suitable for concentrating __________ liquids.
Foaming
Viscous
Very thin
Corrosive
✅ The correct answer is option B.
394. Reason for operating an evaporator in multiple effect is to secure
Increased steam economy
Decreased steam consumption
Both A and B
Increased capacity
✅ The correct answer is option C.
395. One kilogram of water at 0°C is changed to superheated steam of one atm pressure and 300° C. The major heat consumption in the process will be to
Heat the water from 0°C to 100°C
Evaporate the water
To superheat the steam
Data insufficient, can
✅ The correct answer is option B.
396. A perfect black body is a perfect __________ of radiation.
Absorber
Emitter
Both A & B
Neither A nor B
✅ The correct answer is option C.
397. At what value of Prandtl number, the hydrodynamic and thermal boundary layers are identical?
0.5
1
1.5
80
✅ The correct answer is option B.
398. In SI units, fouling factor is expressed in
m²°K/W
W/m²°K
m²°K
m°K/W
✅ The correct answer is option A.
399. The dimensionless group in mass transfer that is equivalent to Prandtl number in heat transfer is
Nusselt number
Sherwood number
Schmidt number
Stanton number
✅ The correct answer is option C.
400. In case of a supercooled solution, which is on the verge of crystallisation, the free energy of the solution as compared to that of the solid is
More
Less
Same
More or less; depends on the nature of solution
✅ The correct answer is option A.