Chemical Heat Transfer Objective Questions and Answers - Set 01 - ObjectiveBooks

Chemical Heat Transfer Objective Questions and Answers - Set 01

Practice Test: Question Set - 01

1. Pick out the wrong statement.
    (A) The value of hydrostatic head increases with increase in vacuum in the effect in a multiple effect evaporator system
    (B) Entering velocity of the liquid in the tubes of natural circulation evaporators is in the range of 0.3 to 0.9 metre/second
    (C) Duhring's plot is used for calculating the concentration of solution
    (D) In a multiple effect evaporation system, the number of effects is limited by the total boiling point rise

2. In a shell and tube heat exchanger,
    (A) The temperature drops in the two fluids and the wall are proportional to individual resistances
    (B) The temperature drop is inversely proportional to the resistance across which the drop occurs
    (C) There is no relationship between temperature drop and resistance
    (D) The relationship is not generalised

3. (NGr × NPr) is called the __________ number.
    (A) Graetz
    (B) Rayleigh
    (C) Nusselt
    (D) Stanton

4. Which of the following has maximum thermal conductivity at the same temperature?
    (A) Steel
    (B) Petrol
    (C) Air
    (D) All have the same conductivity

5. A concentric double pipe heat exchanger as compared to the shell and tube heat exchanger for the same heat load requires
    (A) Less heating surface
    (B) More space
    (C) Lower maintenance cost
    (D) None of these

6. Maximum water velocity in tubes of a 1-2 shell and tube heat exchanger may be around __________ meters/second.
    (A) 1
    (B) 10
    (C) 20
    (D) 30

7. For the same heat load and mass flow rate in the tube side of a shell and tube heat exchanger, one may use multipass on the tube side, because it
    (A) Decreases the pressure drop
    (B) Decreases the outlet temperature of cooling medium
    (C) Increases the overall heat transfer coefficient
    (D) None of these

8. A tank painted with which of the following colored paints, would heat up maximum by radiation from sun?
    (A) Yellow paint
    (B) White paint
    (C) Black paint
    (D) Grey paint

9. Walls of a cubical oven are of thickness l, and they are made of material of thermal conductivity k. The temperature inside the oven is 100°C and the inside heat transfer co-efficient is ‘3k/l’. If the wall temperature on the outside is held at 25°C, what is the inside wall temperature in degree centigrade?
    (A) 35.5
    (B) 43.75
    (C) 81.25
    (D) 48.25

10. Three materials A, B and C of equal thickness and of thermal conductivity of 20, 40 & 60 kcal/hr. m. °C respectively are joined together. The temperature outside of A and C are 30°C and 100°C respectively. The interface between B and C will be at a temperature of __________ °C.
    (A) 40
    (B) 95
    (C) 70
    (D) 50

11. A graph between __________ is called Wilson plot.
    (A) (1/U) Vs. (1/v0.8)
    (B) (1/v0.8) Vs. U
    (C) v0.8 Vs . U
    (D) (1/U) Vs. (1/V)

12. 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
    (A) Black painted bodies only
    (B) All bodies
    (C) Polished bodies only
    (D) A black body

13. For a laminar flow of fluid in a circular tube, 'h1' is the convective heat transfer co-efficient at velocity 'V1'. If the velocity is reduced by half and assuming the fluid properties are constant, the new convective heat transfer co-efficient is
    (A) 1.26 h1
    (B) 0.794 h1
    (C) 0.574 h1
    (D) 1.741 h1

14. Pick out the correct statement.
    (A) 1 kcal/hr.m.°C is equal to 1 BTU/hr. ft.°F
    (B) In steady state heat conduction, the only property of the substance which determines the temperature distribution, is the thermal conductivity
    (C) In unsteady state heat conduction, heat flows in the direction of temperature rise
    (D) In heat transfer by forced convection, Grashoff number is very important

15. Evaporation by thermo compression results in the
    (A) Saving of steam
    (B) Realization of multiple effect economy in a single effect
    (C) Both (a) and (b)
    (D) None of these

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