Conduction & Radiation Heat transfer Questions - Set 32 - ObjectiveBooks
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# Practice Test: Question Set - 32

1. Film boiling occurs at __________ pressure.
(A) Atmospheric
(B) Sub-atmospheric
(C) Negative
(D) Very high

2. In a shell and tube heat exchanger, the tube side heat transfer co-efficient just at the entrance of the tube is
(A) Infinity
(B) Zero
(C) Same as average heat transfer co-efficient for tube side
(D) None of these

3. At Pr > 1, conduction in an ordinary fluid flowing through a heated pipe is limited to the
(A) Buffer zone
(B) Turbulent core
(C) Both (a) and (b)
(D) Viscous sub-layer

4. Which of the following is the most controlling factor for the rate of bubble detachment from the hot solid surface?
(A) Liquid density
(B) Liquid viscosity
(C) Hot surface temperature
(D) Interfacial tension

5. 'Fouling factor' used in the design of a multipass shell and tube heat exchanger is a
(A) Non-dimensional factor
(B) Factor of safety
(C) Conversion factor for individual film heat transfer co-efficient to overall heat transfer co-efficient
(D) None of these

6. Radiation heat transfer rates does not depend upon the
(A) Type of absorbing surface
(B) Distance between the heat source and the object receiving the heat
(C) Surface area and temperature of the heat source
(D) None of these

7. Economy of an evaporator is influenced by the
(A) Steam pressure
(B) Feed temperature
(C) Number of effect
(D) Both (b) & (c)

8. If all the conditions and dimensions are same, then the ratio of velocity through the tubes of a double pass heat exchanger to that through the single pass heat exchanger is
(A) 1
(B) 2
(C) 1/2
(D) 4

9. Circulation pump is located below the evaporator to
(A) Avoid cavitation
(B) Avoid frequent priming
(D) None of these

10. Which of the following is not concerned with the heat transfer?
(A) Brinkman number
(B) Stanton number
(C) Schmidt number
(D) Peclet number

11. Which of the following has the highest thermal conductivity?
(A) Brick
(B) Air
(C) Water
(D) Silver

12. __________ equation relates the thermal conductivity of a solid to its temperature.
(A) Antoine
(B) Kopp's
(C) Lee's
(D) Kistyakowsky

13. A hollow sphere and a solid sphere of the same material and equal radii are heated to the same temperature. In this case,
(A) The cooling rate will be the same for the two spheres and hence the two spheres will have equal temperatures at any instant
(B) Both the spheres will emit equal amount of radiation per unit time in the beginning
(C) Both will absorb equal amount of radiation from the surrounding in the beginning
(D) Both (b) & (c)

14. Unsteady state heat conduction occurs, when
(A) Temperature distribution is independent of time
(B) Temperature distribution is dependent on time
(C) Heat flows in one direction only
(D) Three dimensional heat flow is concerned

15. A __________ surface has the maximum thermal emissivity out of the following.
(A) Black & smooth
(B) Black & rough
(C) White & smooth
(D) White & rough

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