Molecular diffusion in fluids: Introduction; Molecular diffusion; Flux J and N; Steady state molecular diffusion in fluids at rest and in laminar flow; Molecular diffusion in gases through non-diffusing B, equimolal counter diffusion and multicomponent mixtures; Factors affecting gas phase diffusion; Experimental determination of the gas phase diffusion coefficient – Twin bulb method, Stefan tube; Pseudo steady state diffusion through a stagnant gas film; Predictive equations for the gas phase diffusivity; Molecular diffusion in liquids; Predictive equations for liquid phase diffusivity; Diffusion through varying cross-sectional area – Spherical geometry, Tapered tube; Types of diffusion – Knudsen, molecular, and transition, surface diffusion.
Mass transfer coefficients: Mass transfer coefficient in different units; Mass transfer from a gas into a falling liquid film; Eddy diffusion; Prandtl mixing length; Theories of mass transfer - Film theory, Penetration theory, Surface renewal theory; Momentum, heat and mass transfer analogies; dimensionless numbers in mass transfer and their analogues in heat transfer; Mass transfer in wetted wall column; Mass transfer for simple situations; jH and jD factor.
Diffusion in solids: Fick’s law diffusion; Unsteady state diffusion; Diffusion through polymers; Diffusion through crystalline solids; Diffusion in porous solids.
Interphase mass transfer: Equilibrium; Equilibrium relations; Diffusion between phases; Two-resistance theory; Individual and overall mass transfer coefficients; Material balance in continuous contact equipments - steady state cocurrent and countercurrent processes; Stages - continuous cocurrent processes, batch processes, cascades; Kremser equations.
Humidification and Dehumidification: Psychometric chart; Adiabatic saturation curves; Wet bulb temperature; Adiabatic operations - Water cooling with air, Dehumidification of air-water vapour.
Gas absorption: Equilibrium solubility of gases in liquids; Ideal and non-ideal liquid solutions; Choice of solvent for absorption; Material balance for cocurrent and countercurrent gas absorption and stripping; Absorption factor A; Design of packed towers; Concept of HETP, HtG, NtG, HtL, NtL, HtOG, NtOG, HtOL, NtOL.
Drying: Equilibrium; Definitions; Drying operation; Batch drying - rate of batch drying; Mechanisms of batch drying - cross circulation drying, through-circulation drying.
Adsorption: Continuous countercurrent adsorption of one and two components; Rate of adsorption in fixed beds.
Text and References Books:
1. R E Treybal, Mass-Transfer Operations, Third edition, McGraw Hill, New Delhi (2012).
2. K V Narayanan, B Lakshmikutty, Mass Transfer Theory and Applications, CBS Publishers and Distributors, New Delhi (2014).
3. B K Dutta, Principles of Mass Transfer and Separation Processes, Second edition, PHI, New Delhi (2007).
4. A. S. Foust, Principles of Unit Operations, Second edition, Wiley, New York (1980).
5. W L McCabe, J Smith and P Harriot, Unit Operations of Chemical Engineering, Seventh edition, Tata McGraw Hill, New Delhi (2014).
- Teacher: Arun Gupta