Heat Transfer Convection Chemical Engineering MCQ - Set 28 - ObjectiveBooks

Heat Transfer Convection Chemical Engineering MCQ - Set 28

Practice Test: Question Set - 28


1. Mechanical recompression evaporation is used in the production of
    (A) Alcohol
    (B) Distilled water
    (C) Salt
    (D) Fruits jam

2. Pick out the wrong statement.
    (A) Swenson-Walker crystallizer is a batch crystallizer
    (B) Super saturation of the solution is the driving potential for a crystal growth
    (C) The liquor left after the removal of crystals from a solution is called mother liquor
    (D) The first stage of crystal formation is called nucleation

3. The outlet temperature of cooling water in a heat exchanger is generally not allowed to exceed above 50°C in industrial practice mainly to avoid
    (A) Its evaporation loss
    (B) Excessive corrosion
    (C) Uneconomic LMTD
    (D) Decrease in heat exchanger efficiency

4. The number of kg vaporized per kg of steam fed to the evaporator is defined as
    (A) Capacity
    (B) Rate of evaporation
    (C) Economy
    (D) Rate of vaporization

5. The Fourier number (defined as a.t/L2) is used in the analysis of problem involving heat transfer by
    (A) Forced convection
    (B) Natural convection
    (C) Transient conduction
    (D) Steady state conduction

6. Vacuum is generally maintained in the vapor space of an evaporator mainly to
    (A) Get economical temperature difference by using moderate pressure steam
    (B) Facilitate forward feeding in multiple effect evaporation
    (C) Concentrate heat sensitive materials
    (D) Achieve very high concentration of the final product

7. Three solid objects of the same material and of equal mass-a sphere, a cylinder (length = diameter) and a cube are at 500°C initially. These are dropped in a quenching bath containing a large volume of cooling oil each attaining the bath temperature eventually. The time required for 90% change in temperature is the smallest for
    (A) Cube
    (B) Cylinder
    (C) Sphere
    (D) Equal for all the three

8. With increase in porosity, the thermal conductivity of a solid substance
    (A) Increases
    (B) Decreases
    (C) Remains unchanged
    (D) May increase or decrease; depends on the solid

9. Which of the following forced convection heat transfer equation accounts for the liquid viscosity effect for viscous liquids?
    (A) Dittus-Boelter equation
    (B) Sieder-Tate equation
    (C) Nusselt equation
    (D) None of these

10. Which type of heat exchanger is preferred for heavy heat loads?
    (A) Double pipe
    (B) Plate fine
    (C) Series and parallel set of shell and tube
    (D) None of these

11. For condensation of pure vapors, if the heat transfer co-efficients in filmwise and drop-wise condensation are respectively hf and hd, then
    (A) hf = hd
    (B) hf > hd
    (C) hf < hd
    (D) hf could be greater or smaller than hd

12. The unit of heat transfer co-efficient in SI unit is
    (A) J/M2°K
    (B) W/m2°K
    (C) W/m°K
    (D) J/m°K

13. Heat transfer in the laminar sub-layer in case of a liquid flowing through a pipe, is mostly by
    (A) Eddies current
    (B) Conduction
    (C) Convection
    (D) None of these

14. If the baffle spacing in a shell and tube heat exchanger increases, then the Reynolds number of the shell side fluid
    (A) Remains unchanged
    (B) Increases
    (C) Increases or decreases depending on number of shell passes
    (D) Decreases

15. __________ heat exchanger is the most suitable, when the temperature of shell side fluid is much higher than that of tube side.
    (A) Single pass, fixed tube sheet
    (B) U-tube
    (C) Three pass, fixed tube sheet
    (D) None of these

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