Heat Transfer

Question: Conductance is given by(where, x = thickness, A = heat flow area, K = thermal conductivity.)
[A].

x/KA

[B].

KA/x

[C].

K/Ax

[D].

A/Kx

Answer: Option B

Explanation:

No answer description available for this question.

Question: In SI units, fouling factor is expressed in
[A].

m2°K/W

[B].

W/m2°K

[C].

m2°K

[D].

m°K/W

Answer: Option A

Explanation:

No answer description available for this question.

Question: In SI units, thermal conductivity is expressed in
[A].

Watt/m.°K

[B].

Watt/m2. °K

[C].

Watt/m2. °K

[D].

Watt/m4. °K

Answer: Option A

Explanation:

No answer description available for this question.

Question: Circulation pump is located below the evaporater to
[A].

avoid cavitation.

[B].

avoid frequent priming.

[C].

create more suction head.

[D].

none of these.

Answer: Option C

Explanation:

No answer description available for this question.

Question: Evaporator tubes are generally
[A].

horizontal

[B].

vertical

[C].

inclined

[D].

random

Answer: Option B

Explanation:

No answer description available for this question.

Question: LMTD can’t be used as such without a correction factor for the
[A].

multipass heat exchanger.

[B].

baffled heat exchanger.

[C].

condensation of mixed vapour in a condenser.

[D].

all (a) (b) and (c).

Answer: Option D

Explanation:

No answer description available for this question.

Question: Log mean temperature difference (LMTD) cannot be used, if
[A].

heat transfer co-efficient over the entire heat exchanger is not constant.

[B].

there exists an unsteady state.

[C].

the heat capacity is not constant and there is a phase change.

[D].

none of these.

Answer: Option D

Explanation:

No answer description available for this question.

Question: Dietus-Boelter equation cannot be used for molten metals mainly due to its very low
[A].

Prandtl number

[B].

Grashoff number

[C].

thermal conductivity

[D].

viscosity

Answer: Option A

Explanation:

No answer description available for this question.

Question: Multiple effect evaporation accounts for
[A].

steam economy

[B].

lower operating costs

[C].

investment economy

[D].

none of these

Answer: Option A

Explanation:

No answer description available for this question.

Question: In forced circulation, the heating element is injected
[A].

internally

[B].

externally

[C].

both (a) and (a)

[D].

neither (a) nor (b)

Answer: Option A

Explanation:

No answer description available for this question.