August 2022

Question: Alcohols are not suitable as diesel engine fuel because the cetane number of alcohols is
[A].

very low which prevents their ignition by compression.

[B].

very high which prevents their ignition by compression

[C].

zero.

[D].

none of these.

Answer: Option A

Explanation:

No answer description available for this question.

Question: Boiler rating is normally done in terms of
[A].

steam temperature & pressure.

[B].

steam output (tons/hr).

[C].

heat transfer rate (kcal/hr).

[D].

heat transfer area (m2).

Answer: Option B

Explanation:

No answer description available for this question.

Question: Co-efficient of performance of a Carnot cycle refrigerator operating between – 23°C and + 27°C is
[A].

3

[B].

5

[C].

0.5

[D].

1.5

Answer: Option B

Explanation:

No answer description available for this question.

Question: Maximum heat dissipation occurs from a steel wire (k = 0.5 W/m. k) of 15 mm diameter exposed to air (h = 20W/m2 .k), when the insulation thickness is __________ mm.
[A].

15

[B].

25

[C].

10

[D].

30

Answer: Option B

Explanation:

No answer description available for this question.

Question: In case of water (Prandtl number ≈ 6) flowing over a flat plate heated over the entire length, the thermal boundary layer thickness as compared to hydrodynamic boundary layer thickness is
[A].

less

[B].

more

[C].

equal

[D].

unpredictable

Answer: Option A

Explanation:

No answer description available for this question.

Question: In condensers used in thermal power plants, steam is normally used in shell side and cooling water on the tube side, because of the reason that
[A].

compared to the mass flow rate of cooling water, the rate of condensation of steam is invariably smaller.

[B].

maintaining vacuum on tube side is more difficult than that on the shell side.

[C].

water velocity can be increased conveniently to increase the overall heat transfer co-efficient because of its lower specific volume compared to steam.

[D].

condenser can act as a storage unit for condensed steam.

Answer: Option C

Explanation:

No answer description available for this question.

Question: In radiative heat transfer, a grey surface is the one, which has
[A].

emissivity independent of wavelength.

[B].

grey appearance to the eye.

[C].

zero reflectivity.

[D].

equal brightness in all directions.

Answer: Option A

Explanation:

No answer description available for this question.

Question: Out of the following, maximum temperature drop for a given heat flow & for the same thickness will be in the case of
[A].

steel

[B].

glass wood

[C].

copper

[D].

fireclay bricks

Answer: Option B

Explanation:

No answer description available for this question.