chemical engineering MCQs – Page 189

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 Review each marked answer and report any item that may be outdated or unclear.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
3761. The thickness of condensate layer in filmwise condensation depends on the__________________?
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A. All A., B. and C.

B. Liquid flow rate from the surface

C. Condensation rate

D. Surface configuration

3762. In forced convection, the Nusselt number is a function of ____________________?
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A. Pr and Gr

B. Re and Pr

C. Re and Sc

D. Re and Gr

3763. In sub-cooled boiling ?
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A. Very large vapour space is necessary

B. Bubbles from heating surface are absorbed by the mass of the liquid

C. Temperature of the heating surface is more than the boiling point of the liquid

D. Temperature of the heating surface is less than the boiling point of the liquid

3764. When one of the fluids is highly corrosive and has fouling tendency, it should_____________________?
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A. current

B. Flow outside the tube, when the flow is counter-current and inside the tube when the flow is

C. Preferably flow outside the tube

D. Flow at a very slow velocity

E. Preferably flow inside the tube for its easier internal cleaning
3765. With increase in temperature drop (in a shell and tube heat exchanger), the LMTD correction factor, FT_________________?
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A. Remains constant

B. Decreases very rapidly

C. Increases very rapidly

D. Increases linearly

3766. Resistance to heat flow by conduction is proportional to (where, t & ? are thickness & density of the material respectively and A = area normal to the direction of heat flow.) ?
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A. 1/A

B. 1/?

C. t

D. All A., B. & C.
3767. In case of _______________ boiling, the liquid temperature is below the saturation temperature and the boiling takes place in the vicinity of the heated surface?
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A. Nucleate

B. Pool

C. Saturated

D. Local
3768. What is the slope of the operating line in the stripping section of a distillation column ?
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A. ?

B. 0

C. < 1

D. > 1
3769. Vent pipes are provided in a condenser to ________________?
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A. None of these

B. Purge the condenser

C. Facilitate easy cleaning of tubes

D. Remove non-condensable gases
3770. In a shell and tube type heat exchanger, the floating tube bundle heat arrangement is used________________?
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A. In high range of temperature differences

B. Because of its low cost

C. In low range of temperature differences

D. To prevent corrosion of the tube bundles

3771. Grashoff number is given by________________?
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A. gD2??t?/?2

B. gD3??tP2/?

C. gD2??tP2?

D. gD3.?.?t?2/?2
3772. The dimensionless group in mass transfer that is equivalent to Prandtl number in heat transfer is_________________?
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A. Sherwood number

B. Stanton number

C. Nusselt number

D. Schmidt number
3773. In a vertical short tube evaporator (Calandria type), the ______________________?
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A. All A., B. & C.

B. Liquor is inside the tube while the steam is outside the tube

C. Tube dia of 2.5-7.5 cms, tube length of 75-200 cms and cylindrical drum dia of 1-6 metres are

D. mally used

E. rounding tube

F. Area of central downtake is equal to 40 to 100% of total cross-sectional area of the

3774. In a bag filter, the pressure drop increases directly as the___________________?
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A. Viscosity of the gas and inversely as density of the gas

B. None of these

C. Density of the gas and inversely as viscosity of the gas

D. Density of the gas, but is independent of the viscosity of the gas

3775. Nusselt number is the ratio of the temperature gradient at the wall to_________________?
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A. Heat flux

B. None of these

C. That across the entire pipe

D. Temperature difference

3776. Fresh orange juice contains 12% (by weight) solids and the rest water 90% of the fresh juice is sent to an evaporator to remove water and subsequently mixed with the remaining 10% of fresh juice. The resultant product contains 40% solids. The kg of water removed from 1 kg fresh juice is__________________?
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A. 0.5

B. 0.4

C. 0.6

D. 0.7
3777. The maximum heat transfer co-efficient from steam heating will be attained when the steam is_________________?
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A. Saturated

B. None of these

C. Wet

D. Supersaturated

3778. All analogy equations connecting friction factor and heat transfer co-efficient apply only to ___________________?
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A. Wall or skin friction

B. Form friction

C. Both A. and B.

D. Turbulent flow

3779. Heat transfer rate described by Fouriers law will decrease, if the _____________ increases?
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A. Temperature difference

B. Thermal conductivity

C. Heat transfer area

D. Thickness
3780. Open pan evaporators are preferred to be used, when the solution to be concentrated is_________________?
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A. Corrosive

B. Salty

C. Scaling

D. Highly viscous