chemical engineering MCQs – Page 190

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 Review each marked answer and report any item that may be outdated or unclear.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

3781. Which of the following parameters of the fluid is not very important, while deciding its route in a shell and tube heat exchanger ?
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A. Pressure

B. Viscosity

C. Corrosiveness & fouling characteristics

D. Density

3782. What is the geometric mean of two heat transfer areas A1 and A2 ?
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A. ?(A1 + A2)

B. ?(A1 . A2)

C. 2 ?(A1 . A2)

D. ?(A1 . A2)

3783. Sensible heat absorbed by 1 lb of water when it is heated from 32 to 212F may be around ______________ BTU?
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A. 970

B. 3.97

C. Data insufficient, cant be predicted

D. 180

3784. Mc Cable Thiele method used for finding theoretical stages in a distillation column assumes that the_____________________?
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A. Sensible heat differences are small, because the temperature changes from tray to tray is small

B. Liquid/vapor loading across the column remains constant

C. All A., B. and C.

D. Troutons rule is applicable

3785. In a single evaporator system, the steam economy ________________ by creating vacuum in the evaporator?
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A. Decreases

B. May increase or decrease, depends on the vacuum

C. Increases

D. Remain constant

3786. Fluid motion in the natural convection heat transfer between a solid surface and a fluid in contact with it, results from the_________________?
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A. Buoyancy of the bubbles produced at active nucleation site

B. None of these

C. Existence of thermal boundary layer

D. Temperature gradient produced due to density difference

3787. Which of the following is the most widely used heat insulating material for pipelines carrying steam ?
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A. Tar dolomite bricks followed by asbestos

B. Cotton followed by aluminium foil

C. Fireclay refractory followed by aluminium sheet

D. 85% magnesia cement and glass wool

3788. Tube expansion allowances exist in _____________ heat exchanger?
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A. U-tube

B. Multipass fixed tube sheet

C. None of these

D. Single pass fixed tube sheet

3789. To reduce the tube side pressure drop for the same flow rate, the heat exchanger recommended is _______________?
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A. 1-1 heat exchanger

B. 2-4 heat exchanger

C. 3-2 heat exchanger

D. 1-2 heat exchanger

3790. The overall heat transfer co-efficient for a shell and tube heat exchanger for clean surfaces is U0 = 400 W/m2.K. The fouling factor after one year of operation is found to be hd0 = 2000 W/m2.K. The overall heat transfer co-efficient at this time is _____________________?
0

A. 333 W/m2.K

B. 894 W/m2.K

C. 287 W/m2.K

D. 1200 W/m2.K

3791. In a gas-liquid shell and tube heat exchanger, the_________________?
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A. Gases to be heated/cooled is normally routed through the shell side, because the corrosion

B. Presence of a non-condensable gas decreases the condensing film co-efficient

C. rosive in nature

D. Gases under high pressure are routed through the tube side, because high pressure gases are

E. All A, B. & C.

F. sed by the cooling water or steam condensate remain localised to the tubes

3792. Ponchon Savarit method is based on the use of enthalpy concentration diagram, which contains the bubble point curve (saturated liquid curve), dew point curve (saturated vapour curve) and equilibrium tie lines. As compared to McCabe-Thieles method, this method_________________?
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A. is more accurate in finding the number of equilibrium stages

B. s method

C. All A, B. & C.

D. accounts for the enthalpy changes in the process

E. Facilitates direct calculation of heat load on reboiler & condenser from, the diagram used in

3793. The absorptivity of a body is equal to its emissivity _________________?
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A. At a particular temperature

B. None of these

C. Under thermal equilibrium

D. For circular bodies

3794. Absorptivity and reflectivity of a perfect black body are respectively _______________?
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A. 0 and 1

B. 1 and ?

C. 0 and 0.5

D. 1 and 0

3795. To avoid the tearing off the plate of an edge, the margin (i.e., the minimum distance from the centre of the rivet hole to the nearest edge of the plate) should be equal to ____________________?
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A. 0.5 d

B. d

C. 2.5 d

D. 1.5 d

3796. The equation, Nst = (f/2)/[1 + 5 (Npr 1) ?(f/2)], corresponds to ______________ analogy?
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A. Colburn

B. Prandtl

C. Von-Karman

D. Reynolds

3797. The units of resistance to heat transfer is _____________________?
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A. J.m-2.K-1

B. J.m-1.K-1

C. W.m-2.K-1

D. W-1m2K

3798. In common bubble cap distillation column design practice, riser area is approximately equal to (where, Aa = Annular passage area, and Sa = Slot area) ?
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A. Aa = Sa

B. 1.2 Aa = 1.2 Sa

C. Aa = 1.5 Sa

D. Sa = 1.5 Aa

3799. A black body does not ____________ radiation?
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A. Absorb or emit

B. Refract

C. Reflect

D. Both B. & C.

3800. The ratio of velocity head to tube side return loss in case of a multipass shell and tube heat exchanger is ________________?
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A. 2

B. 1/4

C. 2-Jan

D. 4

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