Chemical Engineering Basics

Question: Out of the following, the highest emf for a given temperature is generated by the __________ thermocouple.
[A].

chromel – alumel

[B].

iron – constantan

[C].

platinum – platinum + rhodium

[D].

copper-constantan

Answer: Option B

Explanation:

No answer description available for this question.

Question: __________ number is sometimes used in place of Grashoff number in free convection heat transfer.
[A].

Stanton

[B].

Brinkman

[C].

Rayleigh

[D].

Nusselt

Answer: Option C

Explanation:

No answer description available for this question.

Question: Heat transfer by radiation from a hot body will be most rapid, if its surface is __________ because of its higher emissivity.
[A].

white & rough

[B].

black & rough

[C].

white & polished

[D].

black & polished

Answer: Option B

Explanation:

No answer description available for this question.

Question: Parallel straight line pattern of temperature distribution for both hot and cold fluids is observed in case of heat exchanger of the type
[A].

parallel flow with equal heat capacities.

[B].

counter flow with equal heat capacities.

[C].

counter flow with unequal heat capacities.

[D].

parallel flow with unequal heat capacities.

Answer: Option B

Explanation:

No answer description available for this question.

Question: Nusselt number is related to the Reynolds number (Re) in turbulent & laminar flow respectively as
[A].

Re0.5, Re0.8

[B].

Re0.8, Re-0.5

[C].

Re0.8, Re0.5

[D].

Re-0.8, Re0.5

Answer: Option C

Explanation:

No answer description available for this question.

Question: Nusselt number is related to Grashoff number (Gr) in turbulent & laminar flow respectively, in respect of free convection over a vertical flat plate as
[A].

Gr0.25, Gr

[B].

Gr0.25, Gr0.33

[C].

Gr, Gr0.25

[D].

Gr0.33, Gr0.25

Answer: Option A

Explanation:

No answer description available for this question.

Question: Baffles provided on the shell side of a shell and tube heat exchanger are meant for
[A].

providing support for the tubes.

[B].

improving heat transfer.

[C].

both ‘a’ & ‘b’.

[D].

preventing the fouling of tubes & stagnation of shell side fluid.

Answer: Option C

Explanation:

No answer description available for this question.

Question: A reduction in thermal resistance during heat transfer does not occur in the
[A].

convection heat transfer by stirring the fluid and cleaning the heating surface.

[B].

conduction heat transfer by reduction in the material thickness and increase in the thermal conductivity.

[C].

radiation heat transfer by increasing the temperature and reducing the emis-sivity.

[D].

none of these.

Answer: Option C

Explanation:

No answer description available for this question.

Question: A steam pipe is intended to be insulated with two layers of insulating materials of different thermal conductivities. For minimum heat transfer to take place
[A].

the better insulation material should be put just next to pipe (i.e., inside).

[B].

the better insulating material should be put outside.

[C].

either of the insulating material could be put on either side.

[D].

steam temperature is considered before deciding as to which insulating material is to be put inside (i.e., just next to the pipe).

Answer: Option A

Explanation:

No answer description available for this question.

Question: A thin, flat & square plate measuring 2 m x 2 m is freely hanging in ambient air at 25°C. It is exposed to the solar radiation falling on one side of the plate at the rate of 500 W/m2 . The plate temperature will remain constant at 30°C, if the convective heat transfer co-efficient is __________ W/m2 °C.
[A].

50

[B].

100

[C].

150

[D].

200

Answer: Option B

Explanation:

No answer description available for this question.