Top 1000+ Solved Heat Transfer (HT) MCQ Questions Answer
Q. 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
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'
Q. A multiple effect evaporator as compared to a single effect evaporator of the same capacityhas
a. Lower heat transfer area
b. Lower steam economy
c. Higher steam economy
d. Higher solute concentration in the product
Q. The thickness of condensate layer in filmwise condensation depends on the
a. Condensation rate
b. Surface configuration
c. Liquid flow rate from the surface
d. All (A), (B) and (C)
Q. With increase in temperature, the total emissivity of conductors
a. Increases
b. Decreases
c. Remain same
d. Decreases linearly
Q. Steam economy in case of a triple effect evaporator will be
a. 1
b. < 1
c. > 1
d. Between 0 and 1
Q. Dittus-Boelter equation used for the determination of heat transfer co-efficient is valid
a. For fluids in laminar flow
b. For fluids in turbulent flow
c. When Grashoff number is very important
d. For liquid metals
Q. In a forward feed multiple effect evaporator unit
a. Viscosity of liquid is highest in first effect
b. Transfer from effect to effect is done by pumps
c. No pump is required to withdraw the product from the last effect
d. None of these
Q. In a shell and tube heat exchanger, floating head is used for
a. Large temperature differentials
b. High heat transfer co-efficient
c. Low pressure drop
d. Less corrosion of tubes
Q. The heat transfer co-efficient in film type condensation is __________ that for dropwisecondensation.
a. Greater than
b. Lower than
c. Is same as
d. Half
Q. Dropwise condensation is promoted on a/an __________ surface.
a. Glazed
b. Oily
c. Coated
d. Smooth
Q. Maximum heat transfer rate is obtained in __________ flow.
a. Laminar
b. Turbulent
c. Creeping
d. Transition region
Q. Which of the following parameters of the fluid is not very important, while deciding its routein a shell and tube heat exchanger?
a. Corrosiveness & fouling characteristics
b. Pressure
c. Viscosity
d. Density
Q. In case of a super-cooled solution, which is on the verge of crystallisation, the free energy of the solution as compared to that of the solid is
a. More
b. Less
c. Same
d. More or less; depends on the nature of solution
Q. 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 30°C. The boiling point of the solution is 110°C, 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
a. 3.06 × 105
b. 6.12 × 105
c. 7.24 × 105
d. 9.08 × 105
Q. In a single evaporator system, the steam economy __________ by creating vacuum in theevaporator.
a. Increases
b. Decreases
c. Remain constant
d. May increase or decrease, depends on the vacuum