Chemical Engineering - Heat Transfer

36. 

Nusselt number is the ratio of the

A. temperature gradient of the wall to that across the entire pipe.
B. temperature difference to the temperature gradient at the wall.
C. heat flux at the wall to that across the entire pipe.
D. none of these

Answer: Option C

Explanation:

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37. 

Prandtl number is the ratio of

A. momentum diffusivity to mass diffusivity.
B. momentum diffusivity to thermal diffusivity.
C. thermal diffusivity to mass diffusivity.
D. thermal diffusivity to momentum diffusivity.

Answer: Option B

Explanation:

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38. 

Which of the following parameters is increased by use of finned tube in a multipass shell and tube heat exchanger ?

A. Tube side pressure drop and the heat transfer rate.
B. Convective heat transfer co-efficient.
C. Effective tube surface area for convective heat transfer.
D. All (a) (b) and (c).

Answer: Option D

Explanation:

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39. 

Forced circulation evaporators are useful for the concentration of viscous, salting and scale forming liquors. Which of the following is a forced circulation evaporator?

A. Long vertical evaporator
B. Horizontal tube evaporator
C. Agitated film evaporator
D. Calenderia vertical tube evaporator

Answer: Option C

Explanation:

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40. 

"The ratio of the total emissive power to the absorptivity for all bodies is same at ther-mal equilibrium". This is __________ law.

A. Kirchoffs
B. Planck's
C. Wien's displacement
D. Stefan-Boltzman

Answer: Option A

Explanation:

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