chemical engineering MCQs – Page 207

Practise multiple-choice questions from chemical engineering for competitive examinations and subject revision. Review each marked answer and report any item that may be outdated or unclear.

chemical engineering Mcqs
4121. When vaporisation takes place directly at the heating surface, it is called________________?
comments icon0

A. Film boiling

B. None of these

C. Vapour binding

D. Nucleate boiling
4122. The main function of baffles provided in a shell and tube heat exchanger is to______________?
comments icon0

A. All A , B & C

B. Enhance turbulence

C. Facilitate the cleaning of outer tube surface

D. Hold the tubes in position

4123. If the thermal conductivity of a wall material is independent of temperature, the steady state temperature distribution in the very large thin plane wall having steady, uniform surface temperature follows ____________ law?
comments icon0

A. Hyperbolic

B. Logarithmic

C. Parabolic

D. Linear
4124. Viscous & heat sensitive liquids are concentrated in _____________ evaporators?
comments icon0
A. Agitated film

B. None of these

C. Open pan

D. Long tube

4125. Which of the following is generally considered as opaque surface towards radiations ?
comments icon0

A. Gases

B. Solids

C. Liquids

D. Both B. and C.
4126. For small temperature difference, the heat transfer rate as per Newtons law of cooling is proportional to (where, ?t = excess temperature) ?
comments icon0

A. ?t2

B. ?t

C. ?t3

D. ?(?t)

4127. The equivalent diameter for the annulus of a double pipe heat exchanger, whose inner pipe has fins on the outside is ______________ compared to the same size pipes without fins?
comments icon0

A. Same

B. Unpredictable

C. Less

D. More

4128. Graetz number is given by__________________?
comments icon0
A. mCp/kL

B. kL/mCp

C. k?/mCp

D. mCp/k?

4129. With increase in the distance between the heat source and the object receiving the heat, the radiation heat transfer ?
comments icon0

A. Remain unaffected

B. Increases exponentially

C. Increases

D. Decreases
4130. For a fluid flowing in an annulus space, the wetted perimeter for heat transfer and pressure drop are__________________?
comments icon0
A. Different

B. Same

C. Never different

D. Linearly related

4131. In a liquid-liquid heat exchanger, for the same process temperature, the ratio of the LMTD in parallel flow to the LMTD in counter flow is always__________________?
comments icon0
A. < 1

B. 1

C. ?

D. > 1

4132. With the increase of temperature, the Col-burn jH factor_____________________?
comments icon0

A. Remains unchanged

B. Decreases

C. Increases

D. May increase or decrease; depending on temperature

4133. With increase in temperature, the thermal conductivity of steel___________________?
comments icon0

A. Remains unchanged

B. Decreases

C. Increases

D. Increases exponentially

4134. If average heat transfer co-efficient is ha and the local coefficient at the end of the plate is hl then in case of heat transfer to a fluid flowing over a flat plate, heated over its entire length________________?
comments icon0

A. ha = 0.75 hl

B. ha = 0.5 hl

C. ha = 2hl

D. ha = hl

4135. In natural convection heat transfer, the correlating parameter is the_______________________?
comments icon0
A. Grashoff number

B. Graetz number

C. Bond number

D. Eckert number

4136. In evaporators, lowering the feed temperature_______________?
comments icon0

A. Increases the heating area required

B. Reduces the economy

C. Both A. and B.

D. Decreases the heating area required

4137. Boiling point elevation of an ideal solution_______________?
comments icon0
A. Increases rapidly with temperature rise

B. Decreases rapidly with temperature rise

C. In independent of pressure

D. Both B. and C.

4138. In a heat exchanger, floating head is provided to____________________?
comments icon0

A. Increase the heat transfer area

B. Facilitate cleaning of the exchanger

C. Relieve stresses caused by thermal expansion

D. Increase log mean temperature gradient

4139. Which is the most suitable for the concentration of foamy & frothy liquors ?
comments icon0

A. Agitated film evaporator

B. None of these

C. Open pan evaporator

D. Long tube vertical evaporator
4140. An evaporator while concentrating an aqueous solution from 10 to 40% solids evaporates 30000 kg of water. The amount of solids handled by the system in kg is___________________?
comments icon0

A. 3000

B. 4000

C. 9000

D. 4600