Drying Phenomena

Ibrahim Dincer is a full professor of Mechanical Engineering in the Faculty of Engineering and Applied Science at UOIT. He is Vice President for Strategy in International Association for Hydrogen Energy (IAHE) and Vice-President for World Society of Sustainable Energy Technologies (WSSET). Renowned for his pioneering works in the area of sustainable energy technologies he has authored and co-authored numerous books and book chapters, more than 1000 refereed journal and conference papers, and many technical reports. He has chaired many national and international conferences, symposia, workshops and technical meetings. He has delivered more than 350 keynote and invited lectures. He is an active member of various international scientific organizations and societies, and serves as editor-in-chief, associate editor, regional editor, and editorial board member on various prestigious international journals. He is a recipient of several research, teaching and service awards, including the Premier's research excellence award in Ontario, Canada in 2004. He has made innovative contributions to the understanding and development of sustainable energy technologies, including drying systems and applications, and his group has developed various novel technologies/methods/models/etc. He has recently been identified as one of the 2014's Most Influential Scientific Minds in Engineering. This honour, presented by Thomson Reuters, is given to researchers who rank among the top 1% most cited for their subject field and year of publication, earning the mark of exceptional impact. Calin Zamfirescu is a senior researcher in Dr. Dincer's group at UOIT where he has been working since 2007. His research falls in the field of clean energy technology and process engineering. He was a tenure-track assistant professor of mechanical engineering for four years at Technical University of Civil Engineering of Bucharest, Romania, where he received his PhD in 1999. He was awarded with six research fellowships during five years at the Universities of Delft (in the Netherlands), Duke (in North Carolina, USA) and Henri Poincare (in Nancy, France). He has co-authored some books and more that 50 peer-reviewed papers in well-recognized journals.

Preface xi Nomenclature xv 1 Fundamental Aspects 1 1.1 Introduction 1 1.2 Fundamental Properties and Quantities 2 1.3 Ideal Gas and Real Gas 13 1.4 The Laws of Thermodynamics 19 1.5 Thermodynamic Analysis Through Energy and Exergy 24 1.5.1 Exergy 24 1.5.2 Balance Equations 27 1.6 Psychometrics 36 1.7 Heat Transfer 45 1.7.1 General Aspects 45 1.7.2 Heat Transfer Modes 48 1.7.3 Transient Heat Transfer 54 1.8 Mass Transfer 58 1.9 Concluding Remarks 63 1.10 Study Problems 63 References 65 2 Basics of Drying 67 2.1 Introduction 67 2.2 Drying Phases 68 2.3 Basic Heat and Moisture Transfer Analysis 69 2.4 Moist Material 76 2.5 Types of Moisture Diffusion 81 2.6 Shrinkage 82 2.7 Modeling of Packed-Bed Drying 86 2.8 Diffusion in Porous Media with Low Moisture Content 88 2.9 Modeling of Heterogeneous Diffusion in Moist Solids 90 2.10 Conclusions 97 2.11 Study Problems 97 References 98 3 Drying Processes and Systems 99 3.1 Introduction 99 3.2 Drying Systems Classification 100 3.3 Main Types of Drying Devices and Systems 105 3.3.1 Batch Tray Dryers 105 3.3.2 Batch Through-Circulation Dryers 106 3.3.3 Continuous Tunnel Dryers 108 3.3.4 Rotary Dryers 110 3.3.5 Agitated Dryers 114 3.3.6 Direct-Heat Vibrating-Conveyor Dryers 116 3.3.7 Gravity Dryers 117 3.3.8 Dispersion Dryers 119 3.3.9 Fluidized Bed Dryers 128 3.3.10 Drum Dryers 130 3.3.11 Solar Drying Systems 132 3.4 Processes in Drying Systems 137 3.4.1 Natural Drying 137 3.4.2 Forced Drying 145 3.5 Conclusions 151 3.6 Study Problems 151 References 152 4 Energy and Exergy Analyses of Drying Processes and Systems 153 4.1 Introduction 153 4.2 Balance Equations for a Drying Process 154 4.3 Performance Assessment of Drying Systems 159 4.3.1 Energy and Exergy Efficiencies 159 4.3.2 Other Assessment Parameters 161 4.4 Case Study 1: Analysis of Continuous-Flow Direct Combustion Dryers 162 4.5 Analysis of Heat Pump Dryers 169 4.6 Analysis of Fluidized Bed Dryers 178 4.6.1 Hydrodynamics of Fluidized Beds 179 4.6.2 Balance Equations 181 4.6.3 Efficiency Formulations 183 4.7 Conclusions 187 4.8 Study Problems 187 References 188 5 Heat and Moisture Transfer 189 5.1 Introduction 189 5.2 Transient Moisture Transfer During Drying of Regularly Shaped Materials 190 5.2.1 Transient Diffusion in Infinite Slab 191 5.2.2 Drying Time of an Infinite Slab Material 200 5.2.3 Transient Diffusion in an Infinite Cylinder 202 5.2.4 Transient Diffusion in Spherical-Shape Material 205 5.2.5 Compact Analytical Solution or Time-Dependent Diffusion in Basic Shapes 208 5.3 Shape Factors for Drying Time 209 5.3.1 Infinite Rectangular Rod of Size 2L x 2 1L 210 5.3.2 Rectangular Rod of Size 2L x 2 1Lx2 2L 210 5.3.3 Long Cylinder of Diameter 2L and Length 2 1L 212 5.3.4 Short Cylinder of Diameter 2 1L and Length 2L 213 5.3.5 Infinite Elliptical Cylinder of Minor Axis 2L and Major Axis 2 1L 213 5.3.6 Ellipsoid Having the Axes 2L, 2 1L, and 2 2L 213 5.4 Moisture Transfer Coefficient and Diffusivity Estimation from Drying Curve 216 5.5 Simultaneous Heat and Moisture Transfer 219 5.6 Models for Heat and Moisture Transfer in Drying 225 5.6.1 Theoretical Models 226 5.6.2 Semitheoretical and Empirical Models for Drying 231 5.7 Conclusions 232 5.8 Study Problems 233 References 234 6 Numerical Heat and Moisture Transfer 237 6.1 Introduction 237 6.2 Numerical Methods for PDEs 239 6.2.1 The Finite Difference Method 240 6.2.2 Weighted Residuals Methods: Finite Element, Finite Volume, Boundary Element 246 6.3 One-Dimensional Problems 249 6.3.1 Decoupled Equations with Nonuniform Initial Conditions and Variable Boundary Conditions 249 6.3.2 Partially Coupled Equations 253 6.3.3 Fully Coupled Equations 256 6.4 Two-Dimensional Problems 261 6.4.1 Cartesian Coordinates 261 6.4.2 Cylindrical Coordinates with Axial Symmetry 271 6.4.3 Polar Coord