Falling Films in Desalination: A Computational Approach

Falling Films in Desalination: A Computational Approach

by Henning Raach

NOOK Book(eBook)

$154.99

Available on Compatible NOOK Devices and the free NOOK Apps.
WANT A NOOK?  Explore Now
LEND ME® See Details

Overview

This book covers the simulation of evaporating saltwater falling films with and without turbulence wires. The methods presented within can be applied to a variety of applications including the food and pharmaceutical industry, as well as in nuclear technology. This topic is ideal for researchers in chemical engineering.



Related collections and offers

Product Details

ISBN-13: 9783110591859
Publisher: De Gruyter
Publication date: 08/05/2019
Sold by: Barnes & Noble
Format: NOOK Book
Pages: 197
File size: 17 MB
Note: This product may take a few minutes to download.
Age Range: 18 Years

About the Author

Henning Raach, scientific author, physicist and thermal process engineer, Darmstadt, DE.

Table of Contents

Preface vii

1 Introduction 1

2 Desalination 3

2.1 Reverse osmosis 4

2.2 Saline distillation 6

2.2.1 Multistage flash evaporation 7

2.2.2 Multi-effect distillation 8

2.2.3 The EasyMED project 9

3 Physical foundations 13

3.1 Single phase flow 13

3.1.1 Four different descriptions of fluid flow 13

3.1.2 The substantial derivative 13

3.1.3 The divergence of the velocity 14

3.1.4 The continuity equation 15

3.1.5 The Navier-Stokes equations 16

3.1.6 The energy equation 18

3.1.7 Thermal diffusion 19

3.1.8 Mass transport 20

3.2 Two phase flow 21

3.3 Evaporation 24

3.4 Turbulence 26

3.4.1 What is turbulence? 27

3.4.2 The k-ε model 28

3.4.3 Turbulence near a wall 32

3.4.4 Turbulence near a free surface 34

3.4.5 Extension of the k-epsilon model for a free surface 37

4 Fundamentals of falling films 41

4.1 Flow regimes 42

4.2 The smooth film 43

4.3 The entrance region 47

4.3.1 Hydrodynamic point of view 48

4.3.2 Thermal point of view 49

4.4 Stability 49

4.5 Flow patterns 53

4.6 Experimental correlations 54

4.7 Simulations 58

4.8 Mixture effects 59

4.9 Enhancement of heat transfer 59

4.10 Harmonic waves 60

4.11 Long waves 61

4.12 Zero streamline 62

4.13 Reasonable approximations 62

5 Numerical methods 65

5.1 Finite volumes 65

5.1.1 Diffusion 66

5.1.2 Convection 67

5.1.3 Transient problems 68

5.2 The finite difference method 71

5.3 The finite element method 72

5.4 Volume of fluid (VOF) 72

5.5 Continuum surface force 76

5.6 Flows with phase change 77

6 Simulations with Star-CD 79

6.1 Effect of entrance region 80

6.2 Hydrodynamic studies with one wire 82

6.3 Wake of a wire 84

6.4 Thermal studies 85

6.5 New turbulence model 88

7 Employment of Open FOAM 91

7.1 2D periodically excited waves 91

7.2 3D simulations 93

7.3 Peculiarities of wavy falling films 95

7.4 Numerical experiments with wires 100

8 A Lesson from FS3D 105

9 Original programs 107

9.1 One-dimensional model with VOF 107

9.1.1 Effect of salinity 108

9.1.2 Boiling point elevation 108

9.1.3 Outline of the program 109

9.1.4 Results of 1D simulations 113

9.1.5 Refinementof ID model 114

9.2 Two-dimensional simulations with adaptive grid 116

9.2.1 Comparison of ID and 2D models 118

9.3 Conjugate heat transfer 119

9.4 Long wave equations 122

9.5 Harmonic waves 124

9.5.1 An efficient algorithm 125

9.5.2 A more complex program 126

9.6 With input from OpenFOAM 129

9.6.1 Reading out 129

9.6.2 Without convection 131

9.6.3 With convection 132

9.6.4 Random excitation 133

9.7 The evaporation rate 133

10 Generalization 137

11 Discussion and conclusion 141

A Proof of equation (9.30) 143

B InterFoam 145

B.1 The directory constant 145

B.2 The directory system 145

B.3 The directory θ 149

B.4 Running the program 151

C Thinter 153

C.1 How to compile thinter 155

C.2 Test case 157

D Wires 161

E Counterstatement 169

F List of symbols 171

Bibliography 177

Index 185

Customer Reviews