Chemical Engineering

Question: Critical value of the __________ number governs the transition from laminar to turbulent flow in free convection heat transfer.
[A].

Grashoff

[B].

Reynolds

[C].

both ‘a’ & ‘b’

[D].

Prandtl & Grashoff

Answer: Option D

Explanation:

No answer description available for this question.

Question: LMTD for evaporators & condensers for a given terminal parameters & set of conditions for counterflow is equal to that for parallel flow. In such heat exchangers, with one of the fluids condensing or evaporating, the surface area required is the least in the __________ flow.
[A].

parallel

[B].

mixed

[C].

counterflow

[D].

same in either ‘a’, b’ or ‘c’

Answer: Option D

Explanation:

No answer description available for this question.

Question: Intermittant tube cleaning is possible to be done in case of a __________ evaporator.
[A].

basket type

[B].

horizontal tube

[C].

calendria

[D].

none of these

Answer: Option A

Explanation:

No answer description available for this question.

Question: A dephlegmator is a
[A].

total condenser

[B].

vacuum evaporator

[C].

partial condenser

[D].

double pipe heat exchanger

Answer: Option C

Explanation:

No answer description available for this question.

Question: For gases, the thermal conductivity increases with temperature rise. For liquids, with increase in concentration, its thermal conductivity generally
[A].

decreases

[B].

increases

[C].

remains unchanged

[D].

increases exponentially

Answer: Option A

Explanation:

No answer description available for this question.

Question: Multiple effect evaporation is generally recommended, when the
[A].

large scale evaporation of liquor is needed.

[B].

corrosive liquids are to be concentrated.

[C].

fuel is cheaply available.

[D].

evaporation on small scale is to be done.

Answer: Option A

Explanation:

No answer description available for this question.

Question: jH factor for heat transfer is not a function of the __________ number.
[A].

Reynolds

[B].

Nusselt

[C].

Grashoff

[D].

both (b) & (c)

Answer: Option D

Explanation:

No answer description available for this question.

Question: In case of heat flow by conduction for a cylindrical body with an internal heat source, the nature of temperature distribution is
[A].

linear

[B].

hyperbolic

[C].

parabolic

[D].

none of these

Answer: Option C

Explanation:

No answer description available for this question.

Question: Heat transfer co-efficient equation for forced convection, Nu = 0.023 Re0.8 . Prn, is not valid, if the value of
[A].

n = 0.4 is used for heating.

[B].

n = 0.3 is used for cooling.

[C].

Reynolds number for the flow involved is > 10000.

[D].

Reynolds number for the flow involved is < 2100.

Answer: Option D

Explanation:

No answer description available for this question.

Question: Arithmetic mean area can be used in heat transfer problem to calculate the heat flow by conduction through a cylinder which is
[A].

thin walled having the value of Ao Ai/< 2.

[B].

thick walled.

[C].

having the value of Ao/Ai > 2.

[D].

both (b) and (c).

Answer: Option A

Explanation:

No answer description available for this question.