Mass Transfer I - Theory Questions

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1. Derive from first principles an expression for steady state diffusion of a liquid species A through a stagnant liquid species B.
2. Explain the psychrometric chart with the help of a neat sketch. Also indicate the method of obtaining the various characteristic curves for a given gas-solvent vapor system.
3. Discuss the significance and application of psychrometric charts in simultaneous heat/mass transfer operations.
4. Explain the two film theory of interphase mass transfer. Discuss the reasons for modifying this theory later, by Higle and Dauckwefts.
5. Discuss the need for defining the interphase mass transfer resistance in terms of overall coefficients. How they are related to individual coefficients?
6. Define J factors for heat and mass transfer. State its applications and limitations.
7. Find an expression for obtaining the total drying time for the drying of a wet solid material under constant drying conditions of to a final moisture content well below the critical moisture content.
8. Discuss in detail each one of the following processes separately giving an example.

1. Direct fractional crystallization
2. Extractive fractional crystallization
3. Adductive fractional crystallization

1. Discuss the theory of wet-bulb thermometry. Under what conditions the wet-bulb temperature and adiabatic saturation temperature will be identical.
2. Discuss the steady state diffusion of A through a non-diffusing B and show how the diffusion rate will be modified when component B is counter diffusing.
3. State Higbie's theory for mass transfer and the assumptions made in deriving the expression for mass transfer coefficient.
4. Discuss the Reynolds analogy of heat and momentum transport. How they are rectified by Prandtl and Von Karman in their analogies?
5. Discuss in detail the design of a cooling tower based on enthalpy transfer unit concept. State the important assumptions made and the limitations in application.
6. Discuss the concept of the transfer units used in mass transfer problems. How is overall height of a transfer unit related to the individual heights of transfer unit.
7. How does the super-saturation theory explain the phenomenon of crystallization?
8. What is DL law? How is crystal growth controlled in continuous crystallizers?
9. Describe a method to estimate the diffusivity of a volatile solvent into air.
10. Discuss Penetration theory of mass transfer giving its application.
11. Describe the method of obtaining the length and diameter of a rotary dryer.
12. Describe the various types of cooling towers employed in cooling hot water from process plants.
13. State and derive Lewis relationship. What are its applications and limitations?
14. What is psychrometric ratio? Indicate the methods by which the mass transfer coefficient and heat transfer coefficient are obtained when Lewis relationship fails.
15. List and explain the different ways in which the drying rate of a given substance in the constant rate period may be increased.
16. Giving reasons, indicate the type of dryer that can be used for the following purpose:

Last Modified on: 04-Feb-2022

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