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.

Question: A furnace is made of a refractory brick wall of thickness 0.5 metre and thermal conductivity 0.7 W/m.°K For the same temperature drop and heat loss, this refractory wall can be replaced by a layer of diatomaceous earth of thermal conductivity 0.14 W/m.K and thickness __________ metre.
[A].

0.01

[B].

0.1

[C].

0.25

[D].

0.5

Answer: Option B

Explanation:

No answer description available for this question.

Question: Percentage of differential pressure lost in a venturimeter with a tapering of 15° may be about
[A].

1

[B].

10

[C].

25

[D].

50

Answer: Option B

Explanation:

No answer description available for this question.

Question: In case of fluid moving machineries, the relationship between saturation temperature and pressure decides the process of
[A].

water hammer

[B].

cavitation

[C].

flow separation

[D].

turbulent mixing

Answer: Option B

Explanation:

No answer description available for this question.

Question: For the Stoke’s law to be valid in the case of a falling sphere in a fluid, the
[A].

Reynolds number (based on sphere diameter) should be < 1.

[B].

flow around the sphere should be in turbulent region.

[C].

sphere must be metallic.

[D].

fluid density should be constant.

Answer: Option C

Explanation:

No answer description available for this question.