chemical engineering heat transfer chemical engineering MCQs – Page 5

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 Review each marked answer and report any item that may be outdated or unclear.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
81. The wavelength at which the maximum monochromatic emissive power occurs for a black body, is (where, T = absolute temperature of the black body)?
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A. ? 1/T

B. Independent of T

C. ?T

D. ? T4

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

B. Refract

C. Reflect

D. Both B. & C.
83. At constant temperature, the thermal conductivities of gases _____________ with rise in pressure?
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A. Decrease

B. May increase or decrease; depends on the pressure

C. Remain unchanged

D. Increase

84. Reason for operating an evaporator in multiple effects is to secure ___________________?
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A. Increased steam economy

B. Decreased steam consumption

C. Both A. and B.

D. Increased capacity

85. Forced circulation evaporators are normally used for concentrating liquids having ___________________?
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A. Scaling characteristics

B. High viscosity

C. Both A. & B.

D. Neither A. nor B.

86. The equation, Nst = (f/2)/[1 + 5 (Npr 1) ?(f/2)], corresponds to ______________ analogy?
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A. Von-Karman

B. Prandtl

C. Colburn

D. Reynolds

87. The maximum heat transfer co-efficient from steam heating will be attained when the steam is_________________?
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A. Wet

B. None of these

C. Supersaturated

D. Saturated
88. Maximum heat transfer rate is obtained in ______________ flow?
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A. Creeping

B. Turbulent

C. Transition region

D. Laminar

89. A composite wall consists of two plates A and B placed in series normal to the flow of heat. The thermal conductivities are kA and kB and the specific heat capacities are CPA and CPB for plates A and B respectively. Plate B has twice the thickness of plate A. At steady state, the temperature difference across plate A is greater than that across plate B, when_________________?
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A. CPA > CPB

B. kA < 0.5 kB

C. CPA < CPB

D. kA >2 kB

90. 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 Gr

D. Re and Sc

91. LMTD for evaporators & condensers for a given terminal parameters & set of conditions for counter-flow is equal to that for parallel flow. In such heat exchangers, with one of the fluids condensing or evaporating, the surface area required is the least in the ______________ flow?
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A. Parallel

B. Mixed

C. Same in either A , B. or C.

D. Counter flow

92. In Biot number, the characteristic length used is the ratio of the _______________ of the solid?
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A. Surface area to perimeter

B. Volume to surface area

C. Surface area to volume

D. Perimeter to surface area

93. In a gas-liquid shell and tube heat exchanger, the_________________?
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A. All A, B. & C.

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

C. rosive in nature

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

E. Gases to be heated/cooled is normally routed through the shell side, because the corrosion

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

94. The actual temperature drop across the heating surface of an evaporator depends on the_______________?
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A. Pressure difference between the steam chest and the vapor space above the boiling liquid

B. Liquid depth over the heating surface

C. Solution being evaporated

D. All A., B. and C.
95. Duhrings plot is of use in_________________?
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A. Extractive distillation

B. Leaching

C. Absorption

D. Evaporation
96. For what value of Prandtl number, St = f/2 ?
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A. < 1

B. 1

C. > 1

D. 1.5

97. For _______________ Prandtl number values, the heat conduction will be negligible in the buffer zone?
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A. No

B. Low

C. Extremely low

D. High
98. It is not recommended to use a 1-2 shell and tube heat exchanger for a particular heat duty, whenever the LMTD correction factor is___________________?
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A. < 0.50

B. > 0.75

C. < 0.75

D. < 0.25

99. Nusselt number is a function of Prandtl number and ______________ number of fluid in natural convection heat transfer?
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A. Reynolds

B. Biot

C. Stanton

D. Grashoff
100. Heat transfer by conduction results due to the transfer of free electrons, kinetic energy & vibrational energy from one molecule to another. Conduction heat transfer cannot take place____________________?
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A. Between two bodies in physical contact with each other

B. Between two bodies not in physical contact with each other

C. From one part of a body to the another part of the same body

D. Both B & C