Condensation of the saturated vapor on a cold surface
Concentration of a corrosive solution by evaporation
Heat transfer between two highly viscous liquids
Boiling of a liquid on a hot surface
✅ The correct answer is option D.
Engineering MCQs
For the same heat load and mass flow rate in the tube side of a shell and tube heat exchanger, one may use multipass on the tube side, because it
Decreases the pressure drop
Decreases the outlet temperature of cooling medium
Increases the overall heat transfer coefficient
None of these
✅ The correct answer is option C.
The sum of reflectivity and absorptivity for an opaque body is equal to
0.5
1
0
2
✅ The correct answer is option B.
Dietus-Boelter equation used for the determination of heat transfer co-efficient is valid
For fluids in laminar flow
For fluids in tubulent flow
When Grashhoff number is very important
For liquid metals
✅ The correct answer is option B.
At what value of Prandtl number, conduction is negligible in the turbulent core of a fluid flowing through a heated pipe?
0.5
< 0.5
> 0.6
< 0.1
✅ The correct answer is option C.
Which of the following is the most controlling factor for the rate of bubble detachment from the hot solid surface?
Liquid density
Liquid viscosity
Hot surface temperature
Interfacial tension
✅ The correct answer is option D.
Among liquids, water has a comparatively high value of thermal conductivity, due to its
Low density
High viscosity
Partial ionisation
Dense structure
✅ The correct answer is option C.
In case of a vertical tube evaporator, with increase in the liquor level, the __________ is increased.
Velocity of circulation
Liquor-film co-efficient
Both A and B
Neither A and B
✅ The correct answer is option D.
A process stream of dilute aqueous solution flowing at the rate of10 Kg.s⁻¹ is to be heated. Steam condensate at 95°C is available for heating purpose, also at a rate of 10 Kg.s⁻¹. A 1 – 1 shell and tube heat exchanger is available. The best arrangement is
Counter flow with process stream on shell side
Counter flow with process stream on tube side
Parallel flow with process stream on shell side
Parallel flow with process stream on tube side
✅ The correct answer is option A.
For a counter current heat exchanger with Tih = 80°C, T°c = 60°C, T°h = 50°C and Tic = 30°C, and the temperature difference between the two streams being the same everywhere along Z, the direction of flow of hot fluid. The temperature profile should satisfy
d²T/dZ² > 0
d²T/dZ² = 0
d²T/dZ² < 0
dT/dZ = 0
✅ The correct answer is option B.