Exit-fluid temperature > wall temperature
Exit fluid temperature < wall temperature
Exit fluid temperature = wall temperature
Graetz number > 100
✅ The correct answer is option C.
Heat Transfer MCQs
Which of the following has maximum thermal conductivity at the same temperature?
Steel
Petrol
Air
All of the above
✅ The correct answer is option A.
An evaporator while concentrating an aqueous solution from 10 to 40% solids evaporates 30000 kg of water. The amount of solids handled by the system in kg is
4000
9000
4600
3000
✅ The correct answer is option A.
The thermal radiation emitted by a body is proportional to Tn, where T is its absolute temperature. The value of ‘n’ is exactly 4 for
Black painted bodies only
All bodies
Polished bodies only
A black body
✅ The correct answer is option B.
For a multipass shell and tube heat exchanger, the LMTD correction factor is always
1
> 1
< 1
Between 1 & 2
✅ The correct answer is option C.
Choose the correct equation.
Nu = (Re) (Pr) (Gz)
Nu = (Re) (Pr) (St)
Nu = (Re)(Pr)
Nu = (Pr)(St)
✅ The correct answer is option B.
Radiant energy received by a body is proportional to (where, d = the distance between the object emitting radiation and that receiving it.)
√d
d
d2
d1.5
✅ The correct answer is option C.
In a single effect evaporator, the economy is
1
< 1
> 1
None of these
✅ The correct answer is option B.
Condensing film co-efficient for steam on horizontal tubes ranges from 5000 to 15000 Kcal/hr.m² .°C. Condensation of vapor is carried out inside the tube in a shell and tube heat exchanger, when the
Higher condensing film co-efficient is desired
Condensate is corrosive in nature
Lower pressure drop through the exchanger is desired
Temperature of the incoming vapor is very high
✅ The correct answer is option B.
A sphere of radius ‘R₁’ is enclosed in a sphere of radius ‘R₂’. The view (or shape) factor for radiative heat transfer of the outer sphere with respect to the inner sphere is
0
R₂/(R₁+R₂)
1
(R₁/R₂)2
✅ The correct answer is option B.