chemical engineering MCQs – Page 209

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 Review each marked answer and report any item that may be outdated or unclear.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

4161. The interchange factor for radiation heat transfer from surface x to surface y in case of an infinite parallel planes with emissivities ?x & ?y is given by_______________?
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A. ?x + ?y

B. 1/?x + 1/?y

C. ?x . ?y

D. (?x + ?y)/( ?x + ?y ?x . ?y)

4162. The variation of thermal conductivity of a metal with temperature is often correlated using an expression of the form K = K0 + at, where, K is the thermal conductivity and T is the temperature (in K). The units of a in SI system will be________________?
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A. W/m.k2

B. W/m

C. W/m.k

D. None, a is just a number

4163. The ratio of total radiating power to the absorptivity of the body depends upon the _____________ as per Kirchoff?s law?
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A. None of these

B. Temperature of the body

C. Wavelength of radiation

D. Nature of the body

4164. In case of vertical tube evaporator, with increase in liquor level, the overall heat transfer co-efficient______________?
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A. Is not affected

B. May increase or decrease; depends on the feed

C. Decreases

D. Increases

4165. Reynolds analogy states that (where, St = Stanton number f = friction factor) ?
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A. St = f/2

B. St = 4f

C. St = f/4

D. St = f1/2

4166. Unsteady state heat conduction occurs, when_______________?
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A. Heat flows in one direction only

B. Temperature distribution is dependent on time

C. Temperature distribution is independent of time

D. Three dimensional heat flow is concerned

4167. Circulation pump is located below the evaporator to___________________?
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A. Avoid cavitation

B. Create more suction head

C. None of these

D. Avoid frequent priming

4168. Mode of heat transfer involved in the cooling of air cooled internal combustion engine is_________________?
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A. Natural convection

B. Conduction

C. Forced convection

D. None of these

4169. In a backward feed multiple effect evaporator ___________________ ?
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A. Feed is introduced in the first effect

B. No pumps are required between successive effects

C. Feed flows from low pressure to high pressure

D. None of these

4170. Double pipe heat exchangers are preferably useful, when____________________?
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A. High viscosity liquid is to be cooled

B. A corrosive liquid is to be heated

C. Requirement of heat transfer area is low

D. Overall heat transfer co-efficient is very high

4171. Analogy between mass and heat transfer is not applicable in case of____________________?
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A. Same velocity profile or equal eddy diffusivities

B. Thermal or pressure mass diffusion

C. Viscous heating or chemical reaction

D. Both B. and C.

4172. Steam side heat transfer co-efficient in an evaporator is in the range of ______________ kcal/hr.m2C?
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A. 100-500

B. 5000-15000

C. Oct-50

D. 1000-1500

4173. The steam ejector is used to__________________?
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A. Create vacuum

B. None of these

C. Superheat the steam

D. Remove condensate from the steam pipelines

4174. In case of a multipass shell and tube heat exchanger, providing a baffle on the shell side ______________ the heat transfer rate?
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A. May increase or decrease, depends on the type of baffle

B. Increases

C. Does not affect

D. Decreases

4175. Steam consumption in kg/hr in case of an evaporator is given by (where, C & E are capacity the economy of the evaporator respectively) ?
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A. C/E

B. 1/CE

C. CE

D. E/C

4176. A measure of the extent to which viscous heating is important relative to the heat flow resulting from the impressed temperature difference is represented by the _______________ number?
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A. Grashoff

B. Brinkman

C. Stanton

D. Condensation

4177. The type of liquor circulation system to be employed in evaporators (viz. natural or forced circulation) is determined mainly by the ______________ of the liquid?
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A. Corrosive nature

B. Thermal conductivity

C. Viscosity

D. Density

4178. If h1 = inner film co-efficient and /h2 = outer film co-efficient, then the overall heat transfer co-efficient is________________?
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A. Dependent on metal resistance

B. Always higher than h2

C. Always between h1 and h2

D. Always less than h1

4179. Which characteristic of a fluid is not important in deciding its route in a shell and tube heat exchanger ?
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A. Fouling characteristic

B. Corrosiveness

C. Viscosity

D. None of these

4180. The inside heat transfer co-efficient in case of turbulent flow of liquid in the tube side in a 1-2 shell and tube heat exchanger is increased by ______________ times, when the number of tube passes is increased to 8?
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A. 20.8

B. 40.4

C. 20.4

D. 40.8

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