# Practice Test: Question Set - 08

**1. View factor is important in heat transfer by**

- (A) Steady state conduction

- (B) Natural convection

- (C) Forced convection

- (D) Radiation

**2. Pick out the wrong statement.**

- (A) Economy of a multiple effect evaporator is not influenced by the
boiling point elevation

- (B) Two identical cubes of iron and copper will have the same heat
content under the same conditions of temperature

- (C) Double pipe heat exchangers are mostly used in the field of
refrigeration

- (D) Finned tube heat exchangers are suitable for heating air by steam

**3. 'Duhring's plot' is of use in**

- (A) Extractive distillation

- (B) Evaporation

- (C) Leaching

- (D) Absorption

**4. The dimensionless group in mass transfer that is equivalent to Prandtl number in heat transfer is**

- (A) Nusselt number

- (B) Sherwood number

- (C) Schmidt number

- (D) Stanton number

**5. Pick out the wrong statement.**

- (A) In drying a solid containing moisture above the critical moisture
content the number of degrees of freedom is 2

- (B) Sherwood number in mass transfer corresponds to Nusselt number in
heat transfer and Schmidt number to Prandtl number

- (C) Forced convection is relatively more effective in increasing the
rate of mass transfer, if Schmidt number is larger

- (D) Hot gases at moderate pressure are usually in the shell side of
shell and tube heat exchangers. At higher pressure, however, it is customary to
put gas in the tube side

**6. Loss of heat from untagged steam pipe to the ambient air is by**

- (A) Conduction

- (B) Convection

- (C) Radiation

- (D) All (a), (b) & (c)

**7. In Biot number, the characteristic length used is the ratio of the __________ of the solid.**

- (A) Volume to surface area

- (B) Perimeter to surface area

- (C) Surface area to volume

- (D) Surface area to perimeter

**8. Heat flux increases with temperature drop beyond the Leiden frost point in the plot of heat flux vs. temperature drop for a boiling liquid, because**

- (A) Convection becomes important

- (B) Conduction becomes important

- (C) Radiation becomes important

- (D) Sub-cooled boiling occurs

**9. Boiling point elevation for a strong and concentrated solution is found by Duhring's rule, which states that at the same pressure, the boiling point of a solution is a linear function of the __________ of pure water.**

- (A) Boiling point

- (B) Dynamic viscosity

- (C) Kinematic viscosity

- (D) Density

**10. In case of heat flow by conduction for a cylindrical body with an internal heat source, the nature of temperature distribution is**

- (A) Linear

- (B) Hyperbolic

- (C) Parabolic

- (D) None of these

**11. The average heat transfer co-efficient over the entire length of the plate (**

*h*) and the local heat transfer co-efficient (_{a}*h*), in case of heat transfer over a flat plate in laminar zone is related as_{L}- (A)

*h*= 0.8

_{a}*h*

_{L}- (B)

*h*= 2

_{a}*h*

_{L}- (C)

*h*=

_{a}*h*

_{L}- (D)

*h*= 5

_{a}*h*

_{L}**12. Which has the lowest Prandtl number?**

- (A) Liquid metal

- (B) Aqueous solution

- (C) Water

- (D) Lube oil

**13. Stefan-Boltzmann law which describes the radiation heat transfer states that, it is proportional to (where,**

*t*= temperature in °C*T*= absolute temperature in ° K)- (A)

*t*

^{4}

- (B)

*T*

^{4}

- (C) 1/

*t*

^{4}

- (D) 1/

*T*

^{4}

**14. The ratio of velocity head to tube side return loss in case of a multipass shell and tube heat exchanger is**

- (A) 2

- (B) 1/2

- (C) 4

- (D) 1/4

**15. The equation, (**

*N*×_{St}*N*) =^{2/3}_{Pr}*f*/2, is the __________ analogy.- (A) Colburn

- (B) Reynolds

- (C) Prandtl

- (D) None of these

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