Drying and Storage of Cereal Grains (eBook)

B. K. Bala (Autor)

eBook Download: PDF

2016 | 2. Auflage
John Wiley & Sons (Verlag)
978-1-119-12424-5 (ISBN)

Infos

Finite Element Analysis and Computational Fluid Dynamics have been introduced in modelling and simulation of drying and storage systems, these techniques are expected to dominate the future research and development of drying and storages, and should reduce losses and improve the quality of agricultural products, enhancing food security globally.

Drying and Storage of Cereal Grains, Second Edition, covers the wide spectrum of drying and storage methods applied to economically important cereal produce, providingnumerical examples for better understanding the complexity in drying and storage systems through modelling and simulation, aiding design and management of drying and storage systems. Chapters 1 to 8 look at air and grain moisture equilibria, psychrometry, physical and thermal properties of cereal grains, principles of air flow, and provide detailed analyses of grain drying.Chapters 9 to 13 focus on temperature and moisture in grain storages, and provide comprehensive treatment of modern grain storage systems. The book also includes a number of unsolved problems at the end of each chapter for further practice.

This revised second edition includes new sections on -

• heat of sorption
• finite element modeling of single kernel
• CFD modeling  of fluidized bed drying
• exergy analysis and neural network modeling
• numerical solution of two dimensional temperature and moisture  changes in stored grain

This book will provide students in agricultural engineering and food engineering with a wide spectrum of drying and storage studies previously unavailable in a single monograph. It will also serve as an excellent reference for practicing agricultural engineers, food engineers and food technologists.

B K Bala, Department of Agro Product Processing Technology, Jessore University of Science and Technology, Bangladesh.

Inhalt

Title Page 5
Copyright 6
Contents 7
Foreword to the Second Edition 13
Foreword to the First Edition 15
Preface 17
Chapter 1 Principles of Drying 19
1.1 Introduction 19
1.2 Losses of Crops 20
1.3 Importance of Drying 20
1.4 Principles of Drying 20
Reference 21
Further Reading 21
Chapter 2 Moisture Contents and Equilibrium Moisture Content Models 23
2.1 Introduction 23
2.2 Moisture Content Representation 23
2.3 Determination of Moisture Content 25
2.3.1 Direct Methods 26
2.3.2 Indirect Methods 28
2.4 Grain Sampling 30
2.5 Equilibrium Moisture Content 30
2.6 Determination of Static Equilibrium Moisture Content 35
2.7 Static Equilibrium Moisture Content Models 38
2.8 Net Isosteric Heat of Sorption 40
Exercises 46
References 46
Chapter 3 Psychrometry 49
3.1 Introduction 49
3.2 Psychrometric Terms 49
3.2.1 Humidity Ratio 50
3.2.2 Relative Humidity 50
3.2.3 Specific Volume 51
3.2.4 Vapour Pressure 51
3.2.5 Dry Bulb Temperature 51
3.2.6 Dew Point Temperature 51
3.2.7 Wet Bulb Temperature 52
3.2.8 Enthalpy 52
3.2.9 Adiabatic Wet Bulb Temperature 53
3.2.10 Psychrometric Wet Bulb Temperature 54
3.3 Construction of Psychrometric Chart 56
3.4 Use of Psychrometric Chart 57
3.4.1 Sensible Heating and Cooling 57
3.4.2 Heating with Humidification 58
3.4.3 Cooling with Humidification 59
3.4.4 Cooling with Dehumidification 59
3.4.5 Drying 60
3.4.6 Mixing of Air Streams 61
3.4.7 Heat Addition with Air Mixing 63
3.4.8 Drying with Recirculation 64
Exercises 70
References 72
Further Reading 72
Chapter 4 Physical and Thermal Properties of Cereal Grains 73
4.1 Introduction 73
4.2 Structure of Cereal Grains 73
4.3 Physical Dimensions 73
4.4 1000 Grain Weight 74
4.5 Bulk Density 75
4.6 Shrinkage 75
4.7 Friction 76
4.7.1 Angle of Internal Friction and Angle of Repose 77
4.7.2 Coefficient of Friction 77
4.8 Specific Heat 79
4.9 Thermal Conductivity 81
4.9.1 Theory 81
4.9.2 Apparatus and Measurement 83
4.10 Latent Heat of Vaporization of Grain Moisture 84
4.10.1 Determination of Latent Heat of Vaporization of a Grain 85
4.11 Heat Transfer Coefficient of Grain Bed 87
4.11.1 Dimensional Analysis 88
4.11.2 Comparison of Theory and Experiment 88
4.11.3 Determination of Volumetric Heat Transfer Coefficient 90
Exercises 94
References 96
Further Reading 98
Chapter 5 Airflow Resistance and Fans 99
5.1 Airflow Resistance 99
5.1.1 Non-linear Airflow Analysis 101
5.2 Fans 109
5.2.1 Fan Performance 110
5.2.2 Centrifugal Fan Laws 113
5.2.3 Fan Selection 115
5.2.4 Effect of Change in Fan Speed 116
5.2.5 Effect of Change in Speed and System Resistance 117
5.2.6 Fans in Series and Parallel 117
5.3 Duct Design for On-Floor Drying and Storage System 120
Exercises 121
References 123
Chapter 6 Thin Layer Drying of Cereal Grains 125
6.1 Theory 125
6.2 Thin Layer Drying Equations 127
6.2.1 Empirical Drying Equations 127
6.2.2 Theoretical Drying Equations 128
6.2.3 Semi-Theoretical Drying Equations 131
6.2.4 Comparison of Thin Layer Drying Equations 132
6.3 Development of Thin Layer Drying Equations 134
6.3.1 Drying Rate 137
6.4 Drying Parameters 137
6.4.1 Drying Rate Constant and Diffusion Coefficient 138
6.4.2 Dynamic Equilibrium Moisture Content 145
6.5 Finite Element Modelling of Single Kernel 151
6.5.1 Finite Element Model Formulation 151
6.5.2 Finite Difference Solution in Time 156
6.5.3 Discretization of the Domain 156
Exercises 158
References 160
Further Reading 163
Chapter 7 Deep-Bed and Continuous Flow Drying 165
7.1 Introduction 165
7.2 Deep-Bed Drying Models 165
7.2.1 Logarithmic Models 166
7.2.2 Partial Differential Equation Models 166
7.2.3 Comparison of Deep-Bed Drying Models 167
7.3 Development of Models for Deep-Bed Drying 167
7.3.1 Logarithmic Model 168
7.3.2 Partial Differential Equation Model 174
7.3.3 Method of Solution 178
7.3.4 Condensation Procedure 179
7.3.5 Sensitivity Analysis 187
7.3.6 Comparison of Simulated Drying with Experimental Results 187
7.3.7 Comparison of Direct, Indirect and Recirculating Direct Fired Drying 188
7.4 Development of Models for Continuous Flow Drying 189
7.4.1 Crossflow Model 191
7.4.2 Fluidized Bed Drying Model 198
7.5 CFD Modelling of Fluidized Bed Drying 203
7.5.1 Continuity Equation 203
7.5.2 Momentum Conservation Equations 204
7.5.3 Energy Conservation Equation 204
7.5.4 User-Defined Scheme (UDS) 205
7.5.5 CFD Analysis 205
Exercises 208
References 211
Further Reading 212
Chapter 8 Grain Drying Systems 213
8.1 Introduction 213
8.2 Solar Drying Systems 213
8.3 Batch Drying Systems 217
8.4 Continuous-Flow Drying Systems 218
8.4.1 Crossflow Dryer 218
8.4.2 Concurrent Flow Dryer 218
8.4.3 Counterflow Dryer 220
8.5 Safe Temperature for Drying Grain 220
8.6 Hydrothermal Stresses during Drying 221
8.7 Energy and Exergy Analysis of Drying Process 222
8.7.1 Drying Efficiency 223
8.7.2 Exergy Analysis through the Analysis of Second Law of Thermodynamics 223
8.8 Neural Network Modelling 224
8.8.1 Structure of ANN Model 225
8.8.2 Training of ANN Model 226
8.9 Selection of Dryers 227
Exercises 229
References 230
Further Reading 231
Chapter 9 Principles of Storage 233
9.1 Introduction 233
9.2 Principles of Storage 233
9.3 Interrelations of Physical, Chemical and Biological Variables in the Deterioration of Stored Grains 236
9.4 Computer Simulation Modelling for Stored Grain Pest Management 237
References 238
Further Reading 239
Chapter 10 Temperature and Moisture Changes During Storage 241
10.1 Introduction 241
10.2 Qualitative Analysis of Moisture Changes of Stored Grains in Cylindrical Bins 241
10.3 Temperature Changes in Stored Grains 243
10.4 Temperature Prediction 243
10.4.1 The Differential Equation of Heat Conduction in Cylindrical Coordinate System 244
10.4.2 Numerical Method 245
10.5 Numerical Solution of One-Dimensional Heat Flow 245
10.6 Numerical Solution of Two-Dimensional Heat and Moisture Flow 250
10.6.1 Heat Transfer Equation 251
10.6.2 Mass Transfer Equation 252
10.7 Simultaneous Momentum, Heat and Mass Transfer during Storage 267
10.7.1 The Energy Balance Equation 268
10.7.2 The Mass Balance Equation 269
10.7.3 The Momentum Balance Equation 269
10.7.4 Finite Difference Formulation 270
10.8 CFD Modelling of Grain Storage Systems 276
10.8.1 Continuity Equation 276
10.8.2 Momentum Conservation Equations 276
10.8.3 Energy Conservation Equation 276
10.8.4 User-Defined Function 276
Exercises 278
References 280
Further Reading 280
Chapter 11 Fungi, Insects and Other Organisms Associated with Stored Grain 281
11.1 Introduction 281
11.2 Fungi 281
11.2.1 Field Fungi 283
11.2.2 Intermediate Fungi 283
11.2.3 Storage Fungi 283
11.3 Insects 285
11.3.1 Insect Species 286
11.3.2 Grain Temperature and Moisture Content 287
11.4 Mites 288
11.5 Rodents 288
11.6 Respiration and Heating 288
11.7 Control Methods 289
References 290
Further Reading 290
Chapter 12 Design of Grain Storages 291
12.1 Introduction 291
12.2 Structural Requirements 291
12.2.1 Janssen Equation 291
12.2.2 Rankine Equation 295
12.2.3 Airy Equation 296
12.3 Construction Materials 298
Exercises 306
References 306
Chapter 13 Grain Storage Systems 307
13.1 Introduction 307
13.2 Traditional Storage Systems 308
13.3 Modern Storage Systems 308
13.3.1 Bagged Storage System 308
13.3.2 Silo Storage System 309
13.3.3 Airtight Grain Storage 310
13.3.4 Aerated Storage System 315
13.3.5 Low-Temperature Storage System (Grain Chilling by Refrigeration) 319
13.3.6 Controlled Atmosphere Storage Systems 322
13.3.7 Damp Grain Storage System with Chemicals 324
References 328
Further Reading 331
Appendix A: Finite Difference Approximation 333
Appendix B: Gaussian Elimination Method 335
Appendix C: Finite Element Method 339
References 341
Appendix D: Computational Fluid Dynamics 343
Further Reading 349
Index 351
EULA 354

Produkt-Details

• Erscheint lt. Verlag: 4.11.2016
• Sprache: englisch
• Themenwelt: Naturwissenschaften ► Biologie
• Themenwelt: Technik ► Lebensmitteltechnologie
• Themenwelt: Weitere Fachgebiete ► Land- / Forstwirtschaft / Fischerei
• Schlagworte: Agriculture • air flow • Backwaren, Getreideerzeugnisse • Bakery & Cereals • cereal • CFD • crops • drying • Feldfrüchte • Feldfrüchte • finite element analysis • Food Quality Assurance • Food Science & Technology • Grain • Landwirtschaft • Lebensmittelforschung u. -technologie • Lebensmittel / Qualitätskontrolle • Lebensmittel / Qualitätskontrolle • Moisture • Psychrometry • Storage • Temperature • thermal
• ISBN-10: 1-119-12424-7 / 1119124247
• ISBN-13: 978-1-119-12424-5 / 9781119124245