Heat Transfer

Question: With increase in temperature, the thermal conductivity of fresh lubricating oil
[A].

increases

[B].

decreases

[C].

remains unchanged

[D].

may increase or decrease; depends on its composition

Answer: Option B

Explanation:

No answer description available for this question.

Question: If air (a non-condensing gas) is present in a condensing vapor stream, it will __________ the condensation rate of vapor.
[A].

increase

[B].

decrease

[C].

not affect

[D].

increase the condensing film co-efficient as well as

Answer: Option B

Explanation:

No answer description available for this question.

Question: In case of a multipass shell and tube heat exchanger, providing a baffle on the shell side __________ the heat transfer rate.
[A].

increases

[B].

decreases

[C].

does not affect

[D].

may increase or decrease, depends on the type of baffle

Answer: Option A

Explanation:

No answer description available for this question.

Question: Fouling factor for a heat exchanger is given by (where, U1 = heat transfer co-efficient of dirty surface U2 = heat transfer co-efficient of clean surface)
[A].

U1 – U2

[B].

[C].

[D].

U2 – U1

Answer: Option B

Explanation:

No answer description available for this question.

Question: With increase in temperature, the thermal conductivity of steel
[A].

increases

[B].

decreases

[C].

remains unchanged

[D].

increases exponentially

Answer: Option B

Explanation:

No answer description available for this question.

Question: Mode of heat transfer in which the fluid moves under the influence of changes in fluid pressure produced by external work is called
[A].

radiation

[B].

natural convection

[C].

forced convection

[D].

conduction

Answer: Option C

Explanation:

No answer description available for this question.

Question: Heat transfer rate described by Fourier’s law will decrease, if the __________ increases.
[A].

thermal conductivity

[B].

thickness

[C].

temperature difference

[D].

heat transfer area

Answer: Option B

Explanation:

No answer description available for this question.

Question: Grashoff number, which is defined as g . β(Ts – T∞) ρ2. L3/μ2, is proportional to the ratio of buoyancy force to __________ force.
[A].

viscous

[B].

elastic

[C].

inertial

[D].

none of these

Answer: Option A

Explanation:

No answer description available for this question.

Question: Heat waves
[A].

can not pass through vacuum.

[B].

travel in straight line.

[C].

can be reflected by a mirror.

[D].

both (b) and (c).

Answer: Option D

Explanation:

No answer description available for this question.

Question: In a single evaporator system, the steam economy __________ by creating vacuum in the evaporator.
[A].

increases

[B].

decreases

[C].

remains constant

[D].

may increase or decrease, depends on the vacuum

Answer: Option A

Explanation:

No answer description available for this question.