chemical engineering heat transfer chemical engineering MCQs – Page 11

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 Review each marked answer and report any item that may be outdated or unclear.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

201. A perfect black body is a perfect _____________ of radiation?
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A. Absorber

B. Emitter

C. Both A. & B.

D. Neither A. nor B.

202. Heat transfer co-efficient equation for forced convection, Nu = 0.023 Re 0.8. Pr n, is not valid, if the value of __________________?
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A. Reynolds number for the flow involved is > 10000

B. n = 0.4 is used for heating

C. n = 0.3 is used for cooling

D. Reynolds number for the flow involved is < 2100

203. In a 1-1 concurrent heat exchanger, if the tube side fluid outlet temperature is equal to the shell side fluid outlet temperature, then the LMTD is_________________?
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A. ?

B. Equal to the difference between hot fluid inlet temperature and cold fluid outlet temperature

C. Equal to the difference between hot and cold fluids inlet temperature

D. 0

204. jH factor for heat transfer depends upon the ____________ number?
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A. Prandtl

B. Biot

C. Nusselt

D. Reynolds

205. The units of resistance to heat transfer is _____________________?
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A. W-1m2K

B. J.m-2.K-1

C. J.m-1.K-1

D. W.m-2.K-1

206. In a shell and tube heat exchanger, the shell side fluid velocity can?t be changed by changing the_________________?
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A. Tube pitch

B. Tube diameter

C. Tube layout

D. Number of baffles

207. 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. 180

B. Data insufficient, cant be predicted

C. 970

D. 3.97

208. One kilogram of water at 0C is changed to superheated steam of one atm pressure and 300 C. The major heat consumption in the process will be to________________?
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A. Data insufficient, cant be predicted

B. Heat the water from 0C to 100C

C. To superheat the steam

D. Evaporate the water

209. In case of surface condensers, a straight line is obtained on plotting 1/U vs. ____________ on an ordinary graph paper?
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A. 1/ V? -2

B. 1/V? -0.8

C. V? -2

D. V? -0.8

210. Walls of a cubical oven are of thickness l, and they are made of material of thermal conductivity k. The temperature inside the oven is 100C and the inside heat transfer coefficient is 3k/l. If the wall temperature on the outside is held at 25C, what is the inside wall temperature in degree centigrade ?
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A. 81.25

B. 35.5

C. 48.25

D. 43.75

211. Loss of heat from untagged steam pipe to the ambient air is by __________________?
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A. All A., B. & C.

B. Convection

C. Conduction

D. Radiation

212. Indirect contact heat exchangers are preferred over direct contact heat exchangers, because_________________?
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A. Heat transfer co-efficient are high

B. There is no mist formation

C. Cost of equipment is lower

D. There is no risk of contamination

213. Dropwise condensation is promoted on a/an ______________ surface?
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A. Glazed

B. Coated

C. Smooth

D. Oily

214. Which of the following has the lowest overall heat transfer co-efficient ?
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A. Dowtherm

B. Molten sodium

C. Air

D. Water

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

B. Highly viscous

C. Salty

D. Scaling

216. A process stream of dilute aqueous solution flowing at the rate of10 Kg.s-1 is to be heated. Steam condensate at 95C is available for heating purpose, also at a rate of 10 Kg.s-1. A 1 1 shell and tube heat exchanger is available. The best arrangement is_______________?
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A. Counter flow with process stream on tube side

B. Parallel flow with process stream on shell side

C. Counter flow with process stream on shell side

D. Parallel flow with process stream on tube side

217. The characteristic dimensionless groups for heat transfer to a fluid flowing through a pipe in laminar flow are_______________?
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A. Nu, Gz

B. Nu, Pr

C. Nu, Pr, Re

D. Re.Gz

218. In case of heat transfer by conduction in a hollow cylinder, ______________ mean area is used to calculate the heat transfer rate?
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A. Arithmetic

B. Geometric

C. Logarithmic

D. Either A., B. or C.

219. In case of a multipass shell and tube heat exchanger, the temperature drop in the fluid _______________?
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A. And the wall are proportional to individual resistances

B. And the wall is not related

C. None of these

D. Is inversely proportional to the resistance across which the drop occurs

220. The film co-efficient is decreased due to the presence of non-condensing gases in the vapors. The film co-efficient of superheated vapor as compared to that of saturated vapor is___________________?
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A. Some

B. More

C. Less

D. Either more or less; depends on the nature of vapor

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