chemical engineering heat transfer chemical engineering MCQs – Page 25

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 Review each marked answer and report any item that may be outdated or unclear.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

481. Pick out the wrong statement ?
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A. The equivalent diameter of heat transfer for a duct of square cross-section (having each side as

B. In case of heat transfer by purely forced convection, GR/Re 2 ? 1

C. med and detached from the heating surface

D. The effectiveness of nucleate boiling depends basically on the ease with which the bubbles are

E. Distillation process is not the same as evaporation

F. 216;x) is equal to 4x</strong>

482. Heat transfer co-efficient (h1) for liquids increases with__________________?
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A. Increasing temperature

B. None of these

C. Decreasing temperature

D. Decreasing Reynolds number

483. Thermal diffusivity is the most important in heat transfer by__________________?
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A. Radiation

B. Natural convection

C. Condensation

D. Conduction

484. Baffles are provided in heat exchangers to increase the________________?
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A. Heat transfer co-efficient

B. Fouling factor

C. Heat transfer area

D. Heat transfer rate

485. The number of kg vaporised per kg of steam fed to the evaporator is defined as____________?
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A. Rate of evaporation

B. Capacity

C. Rate of vaporisation

D. Economy

486. For turbulent flow in a tube, the heat transfer co-efficient is obtained from the Dittus- Boelter correlation. If the tube diameter is halved and the flow rate is doubled, then the heat transfer co-efficient will change by a factor of________________?
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A. 6.1

B. 37

C. 1.74

D. 1

487. Dropwise condensation occurs on ______________ surfaces?
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A. Contaminated cooling

B. Smooth clean

C. Polished

D. Clean and dirt free

488. Which of the following is correct ?
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A. Driving force = Rate Resistance

B. Rate = Resistance/Driving force

C. Rate = Driving force Resistance

D. Resistance = Driving force Rate

489. _____________ paint has the minimum absorption co-efficient?
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A. White lead

B. Light cream

C. Grey

D. Black

490. For the same heat transfer area and the terminal conditions, the ratio of the capacities of a single effect evaporator to a triple effect evaporator is_________________?
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A. 3

B. 0.33

C. 1.33

D. 1

491. Heat transfer co-efficient (h) for a fluid flowing inside a clean pipe is given by h = 0.023 (K/D) (DV?/?)0.8 (CP.?/k)0.4. This is valid for the value of NRe equal to_______________?
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A. > 10000

B. 4000

492. A dephlegmator is a_____________________?
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A. Partial condenser

B. Double pipe heat exchanger

C. Vacuum evaporator

D. Total condenser

493. Which is the most suitable for the concert-ration of highly concentrated solution ?
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A. Long tube vertical evaporator

B. None of these

C. Open pan evaporation

D. Agitated film evaporator

494. Pick out the wrong statement ?
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A. n one sequence of heating or cooling i.e., desuperheating & condensation or condensation

B. vent, then it is called a hydrate

C. p; sub-cooling

D. Heat transfer co-efficient during nucleate boiling is not influenced by the agitation imparted

E. al tube cross-sectional area

F. In case of short tube vertical evaporators, area of central downtake is about 50 to 100% of the

495. Pick out the wrong statement?
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A. When a vertical plate is heated in infinite air environmental under natural convection

B. ditions, the velocity profile in air, normal to the plate, exhibits a maximum

C. In process heat exchangers, saturated steam is preferred over the superheated steam

D. tted over the entire wavelength range is equal to emissivity

E. wavelength band between 3 ?m to 4 ?m. The fraction of this energy in the total energy

F. ?1. If the surface temperature is halved, the maximum in the emissive power would occur at

496. Pick out the wrong statement ?
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A. Forced convection is relatively more effective in increasing the rate of mass transfer, if Schmidt number is larger

B. Sherwood number in mass transfer corresponds to Nusselt number in heat transfer and Schmidt number to Prandtl number

C. Hot gases at moderate pressure are usually in the shell side of shell and tube heat exchangers. At higher pressure, however, it is customary to put gas in the tube side

D. In drying a solid containing moisture above the critical moisture content the number of degrees of freedom is 2

497. Pick out the correct statement ?
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A. In steady state heat conduction, the only property of the substance which determines the temperature distribution, is the thermal conductivity

B. 1 kcal/hr.m.C is equal to 1 BTU/hr. ft.F

C. In heat transfer by forced convection, Grashoff number is very important

D. In unsteady state heat conduction, heat flows in the direction of temperature rise

498. Pick out the wrong statement ?
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A. Value of Stefan-Boltzmann constant is 4.876 10-8 KCal/m2.hr.K4

B. Absorptivity of a body approaches unity in case of diffuse reflection

C. With change in temperature, the radiant energy emitted by a black body remains unchanged

D. Absorptivity of a perfectly black body is unity

499. Maximum heat transfer rate can be expected in case of_________?
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