Heat Transfer in Solids Chemical Engineering Questions - Set 06 - ObjectiveBooks

Heat Transfer in Solids Chemical Engineering Questions - Set 06

Practice Test: Question Set - 06

1. Steam economy in case of a triple effect evaporator will be
    (A) 1
    (B) < 1
    (C) > 1
    (D) Between 0 and 1

2. 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

3. 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

4. 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

5. The heat transfer co-efficient in film type condensation is __________ that for dropwise condensation.
    (A) Greater than
    (B) Lower than
    (C) Is same as
    (D) Half

6. Resistance to heat flow by conduction is proportional to (where, t & ρ are thickness & density of the material respectively and A = area normal to the direction of heat flow.)
    (A) t
    (B) 1/ρ
    (C) 1/A
    (D) All (a), (b) & (c)

7. Dropwise condensation is promoted on a/an __________ surface.
    (A) Glazed
    (B) Oily
    (C) Coated
    (D) Smooth

8. Maximum heat transfer rate is obtained in __________ flow.
    (A) Laminar
    (B) Turbulent
    (C) Creeping
    (D) Transition region

9. Which of the following parameters of the fluid is not very important, while deciding its route in a shell and tube heat exchanger?
    (A) Corrosiveness & fouling characteristics
    (B) Pressure
    (C) Viscosity
    (D) Density

10. In case of a super-cooled solution, which is on the verge of crystallization, 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

11. 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 vaporization 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

12. In a single evaporator system, the steam economy __________ by creating vacuum in the evaporator.
    (A) Increases
    (B) Decreases
    (C) Remain constant
    (D) May increase or decrease, depends on the vacuum

13. Fqra cold viscous feed, backward feed gives __________ than forward feed.
    (A) A higher capacity
    (B) A lower capacity
    (C) Lower economy
    (D) None of these

14. Cpµ/K is termed as the __________ number.
    (A) Grashoff
    (B) Nusselt
    (C) Prandtl
    (D) Stanton

15. The overall heat transfer co-efficient for a shell and tube heat exchanger for clean surfaces is U0 = 400 W/m2.K. The fouling factor after one year of operation is found to be hd0 = 2000 W/m2.K. The overall heat transfer co-efficient at this time is
    (A) 1200 W/m2.K
    (B) 894 W/m2.K
    (C) 333 W/m2.K
    (D) 287 W/m2.K

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