chemical engineering heat transfer chemical engineering MCQs – Page 6

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 Review each marked answer and report any item that may be outdated or unclear.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

101. If heat transfer rate varies with the time, it is termed as__________________?
0

A. Monochromatic radiation

B. None of these

C. Forced convection

D. Steady state conduction

102. In a cooling tower, water becomes cool by________________?
0

A. Heat transfer to surroundings

B. Loosing sensible heat

C. Loosing latent heat

D. Vaporisation due to heat loss to air

103. The Sieder-Tate correlation for heat transfer in turbulent flow in pipe gives Nu ? Re0.8, where, Nu is the Nusselt number and Re is the Reynolds number for the flow. Assuming that this relation is valid, the heat transfer co-efficient varies with the pipe diameter D. as _________________?
0

A. D1.8

B. D0.2

C. D-1.8

D. D-0.2

104. It is desired to concentrate a 20% salt solution (20 kg of salt in 100 kg of solution) to a 30% salt solution in an evaporator. Consider a feed of 300 kg/min at 30C. The boiling point of the solution is 110C, the latent heat of vaporisation is 2100 kJ/kg and the specific heat of the solution is 4 kJ/kg.K. The rate at which the heat has to be supplied in (kJ/min) to the evaporator is____________________?
0

A. 7.24 105

B. 6.12 105

C. 9.08 105

D. 3.06 105

105. Radiation energy is emitted by all the substances, which are above____________________?
0

A. 0C

B. 0K

C. 100C

D. Room temperature

106. Thermal diffusivity of a material __________________?
0

A. Is defined as K/? . Cp

B. Has the unit m2 /sec

C. Is the ratio of thermal conductivity to thermal capacity

D. All A., B. and C.

107. The dimensionless group in mass transfer that is equivalent to Prandtl number in heat transfer is_________________?
0

A. Sherwood number

B. Schmidt number

C. Stanton number

D. Nusselt number

108. The ratio of the total emissive power to the absorptivity for all bodies is same at ther-mal equilibrium. This is ______________ law?
0

A. Plancks

B. Stefan-Boltzmann

C. Kirchoffs

D. Wiens displacement

109. The interchange factor for radiation heat transfer from surface x to surface y in case of an infinite parallel planes with emissivities ?x & ?y is given by_______________?
0

A. 1/?x + 1/?y

B. ?x . ?y

C. (?x + ?y)/( ?x + ?y ?x . ?y)

D. ?x + ?y

110. Boiling point of a solution according to Duhrings rule is a linear function of the _____________ of water?
0

A. Boiling point (at the same pressure)

B. Density

C. Thermal conductivity

D. Viscosity

111. Which of the following has maximum thermal conductivity ?
0

A. Nitrogen

B. Tar

C. Iron

D. Coal

112. All analogy equations connecting friction factor and heat transfer co-efficient apply only to ___________________?
0

A. Wall or skin friction

B. Form friction

C. Both A. and B.

D. Turbulent flow

113. Water is normally used as a coolant in the heat exchange equipments mainly because of its___________________?
0

A. Low density

B. Abundance & high heat capacity

C. High fluidity

D. Low viscosity

114. Absorptivity and reflectivity of a perfect black body are respectively _______________?
0

A. 1 and ?

B. 1 and 0

C. 0 and 0.5

D. 0 and 1

115. For what value of Prandtl number, the Col-burn analogy is valid ?
0

A. 1 to 50

B. 1 to 103

C. 0.06 to 120

D. 0.6 to 120

116. Grashoff number, which is defined as g . ? (Ts T?) ?2. L3/?2, is proportional to the ratio of buoyancy force to ____________ force?
0

A. None of these

B. Elastic

C. Inertial

D. Viscous

117. The thermal radiation emitted by a body is proportional to Tn, where T is its absolute temperature. The value of n is exactly 4 for__________________?
0

A. A black body

B. Black painted bodies only

C. Polished bodies only

D. All bodies

118. Which of the following has the lowest Prandtl number ?
0

A. Water

B. Molten sodium (a coolant used in fast breeder reactor)

C. Transformer oil

D. Dilute H2SO4

119. Colburn analogy is applicable for the value of Prandtl number from_________________?
0

A. 0.001 to 1

B. 0.6 to 120

C. 0.5 to 5

D. 120 to 400

120. Forced circulation evaporators are useful for the concentration of viscous, salting and scale forming liquors. Which of the following is a forced circulation evaporator ?
0

A. Horizontal tube evaporator

B. Agitated film evaporator

C. Calandria vertical tube evaporator

D. Long vertical evaporator

Previous Next

Showing 101 to 120 of 511 mcqs