Drying and Storage of Cereal Grains

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

• Foreword to the first edition iiiForeword to the second edition ivChapter 1: Principles of Drying 11.1 Introduction 11.2 Losses of Crops 21.3 Importance of Drying 31.4 Principles of Drying 4Chapter 2: Moisture Contents and Equilibrium MoistureContent Models 62.1 Introduction 62.2 Moisture Content Representation 62.3 Determination of Moisture Content 102.4 Grain Sampling 172.5 Equilibrium Moisture Content 182.6 Determination of Static Equilibrium Moisture Content 232.7 Static Equilibrium Moisture Content Models 272.8 Net Isosteric Heat of Sorption 30Chapter 3: Psychrometry 433.1 Introduction 433.2 Psychrometric Terms 443.2.1 Humidity Ratio 443.2.2 Relative Humidity 453.2.3 Specific Volume 453.2.4 Vapour Pressure 463.2.5 Dry Bulb Temperature 463.2.6 Dew Point Temperature 463.2.7 Wet Bulb Temperature 463.2.8 Enthalpy 473.2.9 Adiabatic Wet Bulb Temperature 483.2.10 Psychrometric Wet Bulb Temperature 513.3 Construction of Psychrometric Chart 533.4 Use of Pschrometric Chart 543.4.1 Sensible Heating and Cooling 553.4.2 Heating with Humidification 563.4.3 Cooling with Humidification 573.4.4 Cooling with Dehumidification 573.4.5 Drying 593.4.6 Mixing of Air Streams 613.4.7 Heat Addition with Air Mixing 643.4.8 Drying with Recirculation 65Chapter 4: Physical and Thermal Properties of Cereal Grains 784.1 Introduction 784.2 Structure of Cereal Grains 784.3 Physical Dimensions 804.4 1000 Grain Weight 804.5 Bulk Density 814.6 Shrinkage 814.7 Friction 834.8 Specific Heat 874.9 Thermal Conductivity 904.10 Latent Heat of Vaporization of Grain Moisture 954.11 Heat Transfer Coefficient of Grain Bed 99Chapter 5: Air Flow Resistance and Fans 1165.1 Air Flow Resistance 1165.1.1 Non-Linear Air Flow Analysis 1185.2 Fans 1285.2.1 Fan Performance 1315.2.2 Centrifugal Fan Laws 1375.2.3 Fan Selection 1375.2.4 Effect of Change in Fan Speed 1385.2.5 Effect of Change in Speed and System Resistance 1395.2.6 Fans in Series and Parallel 1405.3 Duct Design for On-Floor Drying and Storage System 144Chapter 6: Thin Layer Drying of Cereal Grains 1506.1 Theory 1506.2 Thin Layer Drying Equations 1536.2.1 Empirical Drying Equations 1546.2.2 Theoretical Drying Equations 1556.2.3 Semi-theoretical Drying Equations 1596.3 Development of Thin Layer Drying Equations 1646.3.1 Drying Rate 1676.4 Drying Parameters 1676.4.1 Drying Rate Constant and Diffusion Coefficient 1696.4.2 Dynamic Equilibrium Moisture Content 1786.5 Finite Element Modeling of Single Kernel Drying 1856.5.1 Finite Element Model Formulation 1866.5.2 Finite Difference Solution in Time 1926.5.3 Discretization of the Domain 193Chapter 7: Deep Bed and Continuous Flow Drying 2057.1 Introduction 2057.2 Deep Bed Drying Models 2057.2.1 Logarithmic Models 2067.2.2 Partial Differential Equation Models 2067.2.3 Comparison of Deep Bed Drying Models 2087.3 Development of Models for Deep Bed Drying 2097.3.1 Logarithmic Model 2097.3.2 Partial Differential Equation Model 2177.3.3 Method of Solution 2227.3.4 Condensation Procedure 2247.3.5 Sensitivity Analysis 2337.3.6 Comparison of Simulated Drying with Experimental Results 2337.3.7 Comparison of Direct, Indirect and Recirculating Direct Fired Drying 2357.4 Development of Models for Continuous Flow Drying 2377.4.1 Cross Flow Model 2387.4.2. Fluidized Bed Drying Model 2467.5 CFD Modeling of Fluidized Bed Drying 2537.5.1Continuity equation 2547.5.2 Momentum conservation equations 2557.5.3 Energy conservation equation 2567.5.4 User-Defined Scheme (UDS) 2567.5.5 CFD Analysis 256Chapter 8: Grain Drying Systems 2708.1 Introduction 2708.2 Solar Drying Systems 2708.3 Batch Drying Systems 2758.4 Continuous Flow Drying Systems 2778.5 Safe Temperature for Drying Grain 2808.6 Hydro-Thermal Stresses during Drying 2818.7 Energy and Exergy Analysis 2838.8 Neural Network Modeling 2868.8.1 Structure of ANN model 2878.8.2 Training of ANN model 2888.9 Selection of Dryers 290Chapter 9: Principles of Storage 2979.1 Introduction 2979.2 Principles of Storage 2989.3 Interrelations of Physical, Chemical and Biological Variables in the Deterioration of Stored Grains 3019.4 Computer Simulation Modelling for Stored Grain Pest Management 303Chapter 10: Temperature and Moisture Changes during Storage 30710.1 Introduction 30710.2 Qualitative Analysis of Moisture Changes of Stored Grains in Cylindrical Bins 30710.3 Temperature Changes in Stored Grains 30910.4 Temperature Prediction 31110.4.1 The Differential Equation of Heat Conduction in Cylindrical Co-Ordinate System 31110.4.2 Numerical Method 31310.5 Numerical Solution of one-dimensional heat flow 31310.6 Numerical Solution of two-dimensional heat flow and Moisture Flow 32010.6.1 Heat Transfer The Differential Equation of Heat Conduction in Cylindrical Co-Ordinate System 31110.4.2 Numerical Method 31310.7 Simultaneous Momentum, Heat and Mass Transfer 34010.7.1 The Energy Balance Equation 34110.7.2 The Mass Balance Equation 34110.7.3 The Momentum Balance Equation 34210.4.4 Finite Difference Formulation 34310.8 CFD Modelling of Grain Storage Systems 35010.8.1 Continuity Equation 35110.8.2 Momentum Conservation Equation 35110.8.3 Energy Conservation Equation 35110.4.4 User Defined Function 353Chapter 11: Fungi, Insects and Other Organisms Associated with Stored Grain 35811.1 Introduction 35811.2 Fungi 35911.2.1 Field Fungi 36111.2.2 Intermediate Fungi 36111.2.3 Storage Fungi 36111.3 Insects 36411.3.1 Insect Species 36511.3.2 Grain Temperature and Moisture Content 36611.4 Mites 36711.5 Rodents 36711.6 Respiration and Heating 36911.7 Control Methods 371Chapter 12: Design of Grain Storages 37312.1 Introduction 37312.2 Structural Requirements 37312.2.1 Janssen’s Equation 37412.2.2 Rankine’s Equation 37712.2.3 Airy’s Equation 37912.3 Construction Materials 256Chapter 13: Grain Storage Systems 39413.1 Introduction 39413.2 Traditional Storage Systems 39513.3 Modern Storage Systems 39513.3.1 Bagged Storage Systems 39613.3.2 Silo Storage Systems 39613.3.3 Airtight Grain Storage 39813.3.4 Aerated Storage Systems 40613.3.5 Low Temperature Storage System (Grain Chilling by Refrigeration) 41213.3.6 Controlled Atmosphere Storage Systems 41613.3.6 Damp Grain Storage Systems 420Appendix - A Finite Difference Approximation 434Appendix - B Gaussian Elimination Method 436Appendix - C Finite Element Method 438Appendix - D Computational Fluid Dynamics 441Index