Chemical Engineering

Question: If average heat transfer co-efficient is ha and the local coefficient at the end of the plate is hl then in case of heat transfer to a fluid flowing over a flat plate, heated over its entire length
[A].

ha = hl

[B].

ha = 2hl

[C].

ha = 0.5 hl

[D].

ha = 0.75 hl

Answer: Option B

Explanation:

No answer description available for this question.

Question: For a liquid in laminar flow through a very long tube, when the exit fluid temperature approaches the wall temperature, the equation to be used is
[A].

Nu = 0.023 Re0.8 . Pr0.4

[B].

Nu = Gz

[C].

Nu = Gz

[D].

Nu = 2Gz0.5

Answer: Option C

Explanation:

No answer description available for this question.

Question: Choose the correct equation.
[A].

Nu = (Re) (Pr) (Gz)

[B].

Nu = (Re) (Pr) (St)

[C].

Nu = (Re)(Pr)

[D].

Nu = (Pr)(St)

Answer: Option B

Explanation:

No answer description available for this question.

Question: Dietus-Boelter equation used for the determination of heat transfer co-efficient is valid
[A].

for fluids in laminar flow.

[B].

for fluids in tubulent flow.

[C].

when Grashhoff number is very important.

[D].

for liquid metals.

Answer: Option B

Explanation:

No answer description available for this question.

Question: For what value of Prandtl number, St = f/2?
[A].

1.5

[B].

1

[C].

> 1

[D].

< 1

Answer: Option B

Explanation:

No answer description available for this question.

Question: In forced convection, the heat transfer depends on
[A].

Re, Pr

[B].

Re, Gr

[C].

mainly Gr

[D].

Re only

Answer: Option A

Explanation:

No answer description available for this question.

Question: Natural convection is characterised by
[A].

Grashhoff number

[B].

Peclet number

[C].

Reynolds number

[D].

Prandtl number

Answer: Option A

Explanation:

No answer description available for this question.

Question: Conduction occurs in the buffer zone for a fluid flowing through a heated pipe, only when Prandtl number is
[A].

0.1

[B].

>1

[C].

< 1

[D].

l

Answer: Option A

Explanation:

No answer description available for this question.

Question: At Pr > 1, conduction in an ordinary fluid flowing through a heated pipe is limited to the
[A].

buffer zone

[B].

turbulent core

[C].

both (a) and (b)

[D].

viscous sub-layer

Answer: Option D

Explanation:

No answer description available for this question.

Question: Heat transfer co-efficient (h1) for liquids increases with
[A].

increasing temperature.

[B].

decreasing temperature.

[C].

decreasing Reynolds number.

[D].

none of these.

Answer: Option A

Explanation:

No answer description available for this question.