CE 318: Transport Process 2 (Heat and Mass Transfer) Lecture 18: Convective Mass Transfer (Chapter 28) NSC 210 4/16/2015

2 Overview of Mass Transfer Steady State Molecular Diffusion  Fick’s Law for Molecular Diffusion  D A : gas, liquid, solid, biological materials  calculation: different geometries and flow conditions Convective Mass-Transfer Coefficient Unsteady State Diffusion Different parameters for driving force Multi-components

3 Mass Convective Transfer: Drying the Paint

4 Mass Convective Transfer: Dryer

5 Mass Convective Transfer: Membrane Coater

Film Concept: Convective Mass Transfer 6

Fundamental view of heat convection  Dimensional analysis  Exact analysis of the boundary layer  Approximate integral analysis of the boundary layer  Analogy between momentum and heat transfer Empirical equations (next lecture) 7 Outline: h Values ?

8 Heat Convective Transfer

9

Combining of Momentum and Heat Transfer 10 (Chapter 12)

Blasius’s Solution for Heat Transfer 11

Semi-Empirical Method to Estimate h 12 Prandtl Number Nusselt Number

13 Outline: h Values ?

14 Outline: h Values ?

Fundamental view of heat convection  Dimensional analysis  Exact analysis of the boundary layer  Approximate boundary layer analysis  Analogy between momentum, energy and mass transfer Empirical equations (in the future lecture) 15 Outline: k c Values ?

16 Momentum, Heat and Mass Transfer

17 Mass Convective Transfer

18 Mass Convective Transfer

Combining Momentum and Mass Transfer

Blasius’s Solution 20 Blasius’s solution:

Blasius’s Solution (See Chapter 12) 21

Blasius’s Solution for Mass Transfer 22

Blasius’s Solution for Mass Transfer 23 When Sc=1

Blasius’s Solution for Mass Transfer 24 Average mass convective coefficient

Semi-Empirical Method to Estimate k c 25 Schmidt Number Sherwood Number

Fundamental view of heat convection  Dimensional analysis  Exact analysis of the boundary layer  Approximate boundary layer analysis  Analogy between momentum, energy and mass transfer Empirical equations (in the future lecture) 26 Outline: k c Values ?

27 Outline: h Values ? Sc = Pr = 1

28 Outline: h Values ?

29 k c Values ?

Fundamental view of heat convection  Dimensional analysis  Exact analysis of the boundary layer  Approximate integral analysis of the boundary layer  Analogy between momentum and heat transfer Empirical equations (next lecture) 30 Outline: h Values ?

Fundamental view of heat convection  Dimensional analysis  Exact analysis of the boundary layer  Approximate boundary layer analysis  Analogy between momentum, energy and mass transfer Empirical equations (in the future lecture) 31 Outline: k c Values ?

Example