Heat Transfer

Question: Heat flux is the time rate of heat transfer per unit
[A].

length

[B].

area

[C].

volume

[D].

none of these

Answer: Option B

Explanation:

No answer description available for this question.

Question: Maximum heat transfer rate is obtained in __________ flow.
[A].

laminar

[B].

turbulent

[C].

creeping

[D].

transition region

Answer: Option B

Explanation:

No answer description available for this question.

Question: Peclet number (Pe) is given by
[A].

Pe = Re.Pr

[B].

Pe = Re/Pr

[C].

Pe = Pr/Re

[D].

Pe = Nu.Re

Answer: Option A

Explanation:

No answer description available for this question.

Question: In the equation Q = UAΔt; Δt is
[A].

geometric mean temperature difference.

[B].

arithmetic mean temperature difference.

[C].

logarithmic mean temperature difference.

[D].

the difference of average bulk temperatures of hot and cold fluids.

Answer: Option C

Explanation:

No answer description available for this question.

Question: Graetz number is given by
[A].

[B].

[C].

[D].

Answer: Option A

Explanation:

No answer description available for this question.

Question: If h1 = inner film co-efficient and /h2 = outer film co-efficient, then the overall heat transfer co-efficient is
[A].

always less than h1

[B].

always between h1 and h2

[C].

always higher than h2

[D].

dependent on metal resistance

Answer: Option B

Explanation:

No answer description available for this question.

Question: Grashhoff number is given by
[A].

gD3.β.Δtρ2/μ2

[B].

gD2βΔtρ/μ2

[C].

gD2βΔtP2μ

[D].

gD3βΔtP2/μ

Answer: Option A

Explanation:

No answer description available for this question.

Question: For heat flow through very thick walled cylinder, use____mean radius.
[A].

arithmetic

[B].

logarithmic

[C].

geometric

[D].

either (a) or (c)

Answer: Option B

Explanation:

No answer description available for this question.

Question: Heat flux through several resistances in series in analogous to the current flowing through several
[A].

resistances in parallel.

[B].

capacitors in series.

[C].

resistances in series.

[D].

none of these.

Answer: Option C

Explanation:

No answer description available for this question.

Question: An insulator should have
[A].

low thermal conductivity.

[B].

high thermal conductivity.

[C].

less resistance to heat flow.

[D].

a porous structure.

Answer: Option A

Explanation:

No answer description available for this question.