chemical engineering heat transfer chemical engineering MCQs – Page 20

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 Review each marked answer and report any item that may be outdated or unclear.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

381. Shell side pressure drop in a shell and tube heat exchanger does not depend upon the_________________?
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A. Baffle spacing & shell diameter

B. None of these

C. Tube diameter & pitch

D. Viscosity, density & mass velocity of shell side fluid

382. The rate of heat transfer from a vertical plate by natural convection depends upon the temperature differences (?T) between wall and outside bulk. The proportionality is given as______________?
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A. (?T)1/2

B. (?T)5/4

C. (?T)3/4

D. (?T)1/4

383. A 10 cm dia steam pipe, carrying steam at 180C, is covered with an insulation (conductivity = 0.6 W/m.C). It losses heat to the surroundings at 30C. Assume a heat transfer co-efficient of 0.8 W/m2.C for heat transfer from surface to the surroundings. Neglect wall resistance of the pipe and film resistance of steam. If the insulation thickness is 2 cms, the rate of heat loss from this insulated pipe will be__________________?
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A. Less than the steam pipe with 5 cms insulation

B. Equal to that of the un-insulated steam pipe

C. Less than that of the un-insulated steam pipe

D. Greater than that for un-insulated steam pipe

384. When vaporisation takes place directly at the heating surface, it is called________________?
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A. Vapour binding

B. Film boiling

C. None of these

D. Nucleate boiling

385. 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. Wavelength of radiation

C. Temperature of the body

D. Nature of the body

386. For a given ambient air temperature with increase in the thickness of insulation of a hot cylindrical pipe, the rate of heat loss from the surface would ?
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A. First decrease and then increase

B. Decrease

C. First increase and then decrease

D. Increase

387. ____________ chart is known as transient heat conduction chart?
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A. Cox

B. Heislers

C. Molliers

D. Dirhings

388. Heat transfer by radiation between two bodies at T1 & T2 and in an ambient temperature of TaC depends on_____________?
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A. T2 Ta

B. T1 T2

C. T1 Ta

D. None of these

389. In case of _____________ boiling, the bubbles formed on a submerged hot surface get absorbed in the mass of the liquid?
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A. None of these

B. Pool

C. Low pressure

D. Nucleate

390. Steam condensate is recovered by steam traps and recycled for use as boiler feed water, because of its low___________________?
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A. Hardness

B. All A., B. and C.

C. Suspended solids content

D. Dissolved solids content

391. The purpose of providing bleed points in the evaporator is to__________________?
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A. Remove the product

B. Create vacuum

C. Admit the feed

D. Facilitate removal of non-condensable gases

392. 1000 kg of wet solids are to be dried from 60% to 20% moisture (by weight). The mass of moisture removed in kg is__________________?
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A. 200

B. 520

C. 500

D. 400

393. Nusselt number (for forced convection heat transfer) is a function of the _____________ number?
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A. Prandtl

B. Reynolds

C. Both A. & B.

D. Neither A. nor B.

394. Heat waves_____________________?
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A. Cannot pass through vacuum

B. Travel in straight line

C. Can be reflected by a mirror

D. Both B. and C.

395. As the difference between the wall temperature and bulk temperature increases, the boiling heat transfer co-efficient ?
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A. Goes through a maximum

B. Continues to decrease

C. Continues to increase

D. Goes through a minimum

396. 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. 40.4

B. 40.8

C. 20.8

D. 20.4

397. Economy of an evaporator is influenced by the_____________________?
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A. Steam pressure

B. Feed temperature

C. Number of effect

D. Both B. & C.

398. Heat flux is the time rate of heat transfer per unit_______________?
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A. Area

B. None of these

C. Length

D. Volume

399. Hot water (0.01 m3 /min) enters the tube side of a counter current shell and tube heat exchanger at 80C and leaves at 50C. Cold oil (0.05 m3/min) of density 800 kg/m3 and specific heat of 2 kJ/kg.K enters at 20C. The log mean temperature difference in C is approximately ?
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A. 32

B. 45

C. 50

D. 37

400. Steam traps are provided in steam carrying pipelines to_________________?
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A. Condense steam

B. Remove condensate and inert gases

C. Release excess steam pressure by bleeding steam

D. None of these

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