chemical engineering heat transfer chemical engineering MCQs – Page 15

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 Review each marked answer and report any item that may be outdated or unclear.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

281. For specified tube outside diameter, higher BWG means higher___________________?
0

A. Tube thickness

B. Weight per unit length

C. Cross-sectional area

D. None of these

282. 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. None of these

D. Viscosity

283. If a single tube pass heat exchanger is converted to two pass, then for the same flow rate, the pressure drop per unit length in tube side will ________________?
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A. Increase by 216

B. Decrease by 22

C. Increase by 1.8 times

D. Remain unchanged

284. Leidenfrost point is a term concerned with the____________________?
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A. Boiling of a liquid on a hot surface

B. Condensation of the saturated vapor on a cold surface

C. Concentration of a corrosive solution by evaporation

D. Heat transfer between two highly viscous liquids

285. As per Kirchoff?s law, the ratio of the total radiating power to the absorptivity of a body depends on the_______________?
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A. Temperature of the body only

B. Wavelength of monochromatic radiation

C. Both A. and B.

D. Nature of material of body

286. The Fourier number (defined as a.t/L2) is used in the analysis of problem involving heat transfer by_______________?
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A. Transient conduction

B. Natural convection

C. Steady state conduction

D. Forced convection

287. Vibrations in the tubes of a shell and tube heat exchanger is induced due to the _________________?
0

A. Vibrations transmitted through piping and/or supports due to external reasons

B. Flow of fluid on the tube and shell sides

C. All A., B. and C.

D. Oscillations in the flow of shell/tube sides fluid

288. Which of the following is unimportant in forced convection ?
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A. Prandtl number

B. None of these

C. Reynolds number

D. Grashoff number

289. Which of the following forced convection heat transfer equation accounts for the liquid viscosity effect for viscous liquids ?
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A. Nusselt equation

B. None of these

C. Sieder-Tate equation

D. Dittus-Boelter equation

290. Thermal conductivities of most of the liquids _______________ with rise in temperature?
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A. Remains unchanged

B. Decreases

C. Increases

D. May increase or decrease; depends on the liquid

291. Convective heat transfer co-efficient in case of fluid flowing in tubes is not affected by the tube length/diameter ratio, if the flow is in the _____________ zone?
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A. Laminar

B. Transition

C. Both A & B

D. Highly turbulent

292. LMTD correction factor which is to be applied for a cross-flow heat exchanger increases with increase in the number of shell passes. Its value for a single pass cross flow heat exchanger is __________________?
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A. < 1

B. > 1

C. 0

D. 1

293. In a heat exchanger, one transfer unit means___________________?
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A. A section of the exchanger in which change in temperature of one stream equals the average

B. ving force in the section</strong>

C. The size of the exchanger in which heat transfer rate is 1 kcal/hr

D. Both A. and B.

E. None of these

294. Correction is applied to LMTD for __________ flow?
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A. Parallel

B. None of these

C. Cross

D. Counter

295. Which of the following has the minimum absorptivity ?
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A. Aluminium foil

B. Coal dust

C. Refractory bricks

D. Iron plates

296. A metal wire of 0.01 m dia and thermal conductivity 200 W/m.K is exposed to a fluid stream with a convective heat transfer coefficient of 100 W/m2.K. The Biot number is ______________?
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A. 5.6

B. 0.0035

C. 0.025

D. 3.5

297. Low thermal conductivity of heat insulating materials is due to its_______________?
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A. High specific heat

B. Dense structure

C. None of these

D. High proportion of air space

298. The local surface conductance for laminar film condensation on vertical surface is (where, t = film thickness) _________________?
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A. Independent of t

B. ? 1/t

C. ? t

D. ? ?t

299. A diathermanous substance _______________ the thermal radiation completely?
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A. Absorbs

B. Reflects

C. None of these

D. Transmits

300. In case of a vertical tube evaporator, with increase in the liquor level, the ____________ is increased?
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A. Velocity of circulation

B. Liquor-film co-efficient

C. Both A. and B.

D. Neither A. and B.

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