CE 318: Transport Process 2 (Heat and Mass Transfer) Lecture 19: Convective Mass Transfer Between Phases (Chapter 29) NSC 210 4/21/2015

2 About Midterm and Schedule Change Midterm will be posted at UBLearns at 9am Friday (4/24). Midterm covers chapters No recitation this week (4/24). Homework 9 is due on 4/30 (Thursday).

The 3 rd Quiz 3 Quiz 1 st 2 nd 3 rd Average 4.9/106.2/10 Median grade Standard deviation >= (Av. + SD) 1224 Av. – (Av.+SD) 309 (Av.-SD) – Av < (Av.-SD) 1513

Random Thoughts: Tips on Test-Taking 4 Richard Felder

Random Thoughts: Tips on Test-Taking 5 Richard Felder

6 Overview of Mass Transfer Steady State Molecular Diffusion  Fick’s Law for Molecular Diffusion  D A : gas, liquid, solid, biological materials  calculation: Counter-diffusion; Unimolecular diffusion; diffusion/reaction Convective Mass-Transfer Coefficient Unsteady State Diffusion Mass Transfer Equipment Multi-components Discontinuous interface

 General equation for diffusion & convection  Case I: Equimolar counterdiffusion  Case II: B is stagnant (N B = 0) 7 Basic Processes

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) 8 Outline: k c Values ?

9 Mass Convective Transfer

10 Analogies of Transfers

Equilibrium Two-resistance theory –Individual film mass transfer coefficients –Overall mass transfer coefficients Example 11 Outline: Convective MT between Phases Multi-components Discontinuous interface

12 Discontinuous Interface in Mass Transfer: Gas Absorption/Stripping

13 Discontinuous Interface in Mass Transfer: Distillation

Solvent Extraction 14

Solvent Extraction: Soybean Oil Production 15

16 Convective Mass Transfer: Discontinuous Interface

17 Phases at Equilibrium Raoult’s Law Henry’s Law

18 Gas Absorption

19 Convective Mass Transfer: Discontinuous Interface

20 Convective Mass Transfer: Discontinuous Interface

21 Convective Mass Transfer: Discontinuous Interface

“Uphill” Transport 22

Hydrophobic Solute Diffuses From Organophobic (Water) to Organophilic (PEG) Environment Progesterone: LogP=3.5 [octanol]/[water] = = 3,200 23

“One-Way” Diffusion Based on Differential Solubility Sudan IV Dye: logP = 6.7 [octanol]/[water] = = 5,000,000 Water (hydrophilic) Vegetable Oil (hydrophobic) PDMS (hydrophobic) + dye 24

Experimental Demonstration of “One-Way” Diffusion 25 PDMS (hydrophobic) + dye

26 Gas Absorption

Heat Transfer in Series: Plane Walls 27 q

Mass Transfer in Series: Plane Walls 28 q NANA C A1 C A2 C A3 C A4

29 Convective Mass Transfer: Discontinuous Interface

30 Convective Mass Transfer: Discontinuous Interface

31 Example

32 Example 7.4.1