U₁ = U₂
U₂ > U₁
U₁ > U₂
U₁ = dirt factor – U₂
✅ The correct answer is option A.
Engineering MCQs
What is the thermal conductivity of a perfect heat insulator?
Zero
One
∞
Between 0 and ∞
✅ The correct answer is option A.
Which of the following is correct?
Rate = Driving force x Resistance
Driving force = Rate x Resistance
Resistance = Driving force x Rate
Rate = Resistance/Driving force
✅ The correct answer is option B.
Mode of heat transfer involved in the cooling of air cooled internal combustion engine is
Conduction
Natural convection
Forced convection
None of these
✅ The correct answer is option B.
Baffles in the shell side of a shell and tube heat exchanger
Increase the cross-section of the shell side liquid
Force the liquid to flow parallel to the bank
Increase the shell side heat transfer co-efficient
Decrease the shell side heat transfer co-efficient
✅ The correct answer is option C.
Sensible heat absorbed by 1 lb of water when it is heated from 32 to 212°F may be around __________ BTU.
180
970
3.97
Data insufficient, can
✅ The correct answer is option A.
For a laminar flow of fluid in a circular tube, ‘h₁’ is the convective heat transfer co-efficient at velocity ‘V₁’. If the velocity is reduced by half and assuming the fluid properties are constant, the new convective heat transfer co-efficient is
1.26 h₁
0.794 h₁
0.574 h₁
1.741 h₁
✅ The correct answer is option B.
Resistance to heat flow by conduction is proportional to (where, t & ρ are thickness & density of the material respectively and A = area normal to the direction of heat flow. )
T
1/ρ
1/A
All of the above
✅ The correct answer is option D.
Which is the most suitable for the con-certration of highly concentrated solution?
Open pan evaporation
Long tube vertical evaporator
Agitated film evaporator
None of these
✅ The correct answer is option A.
At Pr > 1, conduction in an ordinary fluid flowing through a heated pipe is limited to the
Buffer zone
Turbulent core
Both A and B
Viscous sub-layer
✅ The correct answer is option D.