chemical engineering heat transfer chemical engineering MCQs – Page 19

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 Review each marked answer and report any item that may be outdated or unclear.

chemical engineering heat transfer chemical engineering Mcqs
361. In case of a shell and tube heat exchanger, the minimum and maximum baffle spacing is respectively (where, D = inside diameter of the shell) ?
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A. D/2 and 2 D

B. D/5 and D

C. D/4 and 2 D

D. D and 2 D

362. What is the absorptivity of a black body?
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A. 1

B. 0

C. 0.78

D. 0.95

363. At what value of Prandtl number, the hydrodynamic and thermal boundary layers of a fluid flowing over a heated plate will be identical ?
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A. 1

B. 1

C. None of these

364. A _____________ surface has the maximum thermal emissivity out of the following ?
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A. White & smooth

B. White & rough

C. Black & smooth

D. Black & rough
365. Boiling point elevation of a solution of NaOH _____________________?
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A. Increases rapidly with temperature rise

B. Is almost independent of temperature

C. Is almost independent of pressure

D. Both B. and C
366. Heat transfer by natural convection is enhanced in system with__________________?
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A. Low density change with temperature

B. High viscosity

C. High co-efficient of thermal expansion

D. Low temperature gradients

367. Sensible heat of hot industrial flue gases cannot be recovered by a/an________________?
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A. Ceramic recuperator

B. Regenerator

C. None of these

D. Economiser

368. Which of the following is generally considered as opaque surface towards radiations ?
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A. Gases

B. Solids

C. Liquids

D. Both B. and C.
369. Which of the following is the most controlling factor for the rate of bubble detachment from the hot solid surface ?
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A. Liquid viscosity

B. Liquid density

C. Hot surface temperature

D. Interfacial tension
370. In a forward feed multiple effect, the pressure build up will be____________________?
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A. Least at the inlet of the first effect

B. Highest at the inlet of the last effect

C. Least at the outlet of the last effect

D. Highest at the outlet of the last effect

371. If all the conditions and dimensions are same, then the ratio of velocity through the tubes of a double pass heat exchanger to that through the single pass heat exchanger is_________________?
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A. 4

B. 1

C. 2-Jan

D. 2
372. In a shell and tube heat exchanger, the height of 25 percent cut baffles is equal to (where, D = inside diameter of shell) ?
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A. 0.50 D

B. 0.75 D

C. None of these

D. 0.25 D

373. Removal of ______________ heat is involved in the condensation of a vapor under saturated conditions?
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A. Super

B. Sensible

C. Latent

D. Both B. & C.

374. Reynolds analogy states that (where, St = Stanton number f = friction factor) ?
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A. St = f/4

B. St = f1/2

C. St = 4f

D. St = f/2
375. Log mean temperature difference (LMTD) cannot be used, if ___________________?
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A. Heat transfer co-efficient over the entire heat exchanger is not constant

B. The heat capacity is not constant and there is a phase change

C. None of these

D. There exists an unsteady state

376. Out of 100 kcal/second of incident radiant energy on the surface of a thermally transparent body, 300 kcal/second is reflected back. If the transmissivity of the body is 0.25, the emissivity of the surface will be_________________?
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A. 0.55

B. 0.45

C. 0.85

D. 0.35

377. Harmonic mean temperature difference is given by_________________?
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A. 2 (?T1 . ?T2)/(?T1 ?T2)

B. 2 (?T1 . ?T2)/(?T1 + ?T2)

C. ?(?T1 . ?T2)

D. (?T1 ?T2)/(?T1 . ?T2)

378. The ratio of momentum diffusivity to thermal diffusivity is the ______________ number?
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A. Prandtl

B. Nusselt

C. Stanton

D. Grashoff

379. A 2-4 heat exchanger involves__________________?
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A. Only counter-flow of fluids

B. Only parallel-flow of fluids

C. Both counter and parallel-flow of the fluids

D. Smaller pressure drop compared to 1-2 exchanger

380. In a single effect evaporator, the economy is________________?
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A. < 1

B. > 1

C. None of these

D. 1