It is a pleasure to present this volume consisting of a selection of papers presented at the 4th International Drying Symposium (IDS) held in Kyoto, July 9-12, 1984, under the sponsorship of the Society of Chemi cal Engineers, Japan. This book includes full texts of the ten keynote lectures and several papers which were presented in the technical sessions in the 4th IDS. As editors we had the arduous and unpleasant task of selecting papers for this volume. We were delighted with the high quality manuscripts sub mitted. We are grateful to the authors for their efforts in meeting the manuscript guidelines and also the deadlines. Aside from quality, we have attempted to maintain in this volume a balance of coverage in terms of topics as well as geography. Space restrictions prevented us from presenting all the high quality papers for publication in DRYING 85. Numerous papers of archival interest have been released for general publication in international journals. Several will no doubt appear in Drying Technology - An International Journal. Many others will find their way into other standard engineering journals as well. Over 120 papers from 30 countries were included in the Proceedings volumes distributed to all registrants in Kyoto. Numerous individuals, professional societies and organizations have contributed, directly or indirectly, to the success of the 4th IDS and hence to DRYING 85 as well. We wish to acknowledge in particular the monumental efforts of the Secretary of the 4th IDS, Professor M. Okazaki.

Section I Texts of Keynote Lectures at IDS'86, Kyoto, Japan

Opportunities for Fundamental Research in Drying
Short-cut Calculation for Non-isothermal Drying of Shrinking and Non-shrinking Particles and of Hollow Spheres Containing an Expanding Central Gas Core
Moisture Transport Mechanisms During the Drying of Granular Porous Media
Aspects of Solar Drying
Steam Drying
Control of Food-Quality Factors in Spray Drying
Modelling Continuous Convection Dryers for Particulate Solids - Progress and Problems
Vacuum Contact Drying of Free Flowing Mechanically Agitated Particulate Material
Heat and Mass Transport Properties of Heterogeneous Materials
Section II Drying Theory and Modelling
Influence of Surface Active Agents on the Drying Rate of Solids
Theory of Constant-Rate Expression and Subsequent Relaxation
Importance of Gas Phase Momentum Equation in Drying Above the Boiling Point of Water
Convective Drying of Porous Materials Containing Binary Mixtures
The Mathematical Modelling of Drying Process Based on Moisture Transfer Mechanism
Numerical Modeling of the Drying of Porous Materials
Theoretical Prediction of Moisture Transfer by Convective Drying for a Flat Plate
An Analysis of Drying Rate Mechanism in Complex Solids
Section III Drying of Granular Solids
Particle Velocities in Pneumatic Conveying Dryers
Drying of Granular Particles in a Multistage Inclined Fluidized Bed with Mechanical Vibration
Combined Heat and Mass Transfer During Drying of Molecular Sieve Pellets
Air Drying Kinetics of Biological Particles
Single Tube Heat Transfer in Aerated Vibrated Beds
Indirect Heating of Solid Particles
Heat Transfer Coefficient Between Heating Wall and Agitated Granular Bed
Heat Transfer from Submerged Body Moving in Granular Bed
Section IV Spray Drying
Effect of Droplet Size on the Properties of Spray-Dried Whole Milk
An Assessment of Steam Operated Spray Dryers
Volatile Loss in Spray Drying
The Mathematical Modelling of Cocurrent Spray Drying
Control and Energy Aspects of Milk Powder Spray-Drying in Relation to Product Quality
Section V Vacuum and Freeze Drying
Application of Optimal Control Strategy to Hybrid Mivrowave and Radiant Heat Freeze Drying System
Characteristics of Vibro-Fluidized Bed Freeze Drying
Freeze Drying Characteristics and Transport Properties in Concentrated Coffee Solution System
Freeze-Drying Mechanisms and Drying Rates Under Various Drying Conditions
Freeze-Drying of Concentrated Liquid Foods by Back-Face Heating
Development of New Refrigeration System and Optimum Geometry of the Vapor Condenser for Pharmaceutical Freeze Dryers
Defrosting of Internal Vapor Condenser During Final Drying and its Application to Food Production Freeze Dryers
Section VI Drying of Foodstuffs
Fundamentals of Drying of Foodstuffs
Advances in Optimization of Food Dehydration With Respect to Quality Retention
Drying of Foods With Flue Gas From Natural Gas Risk/Benefit
Acoustic Dewatering and Drying: State of the Art Review
Over-All Drying-Rate Equations of Foodstuffs
Enzyme Inactivation During Drying of a Single Droplet
Flavour Retention on Drying of a Single Droplet Under Various Drying Conditions
Belt Type From Mat Dryers
Section VII Drying in Forest Product Industries
Computer Simulation of a Minton Dryer
Convective Heat Transfer Under Turbulent Impinging Slot Jet at Large Temperature Differences
Mathematical Modeling of Wood Drying From Heat and Mass Transfer Fundamentals
Stochastic Modeling of Lumber Drying in Batch Kilns
High Temperature Convective Drying of Softwood and Hardwood: Drying Kinetics and Product Quality Interactions
Section VIII Drying of Coal
Coupled Drying and Devolatilization of Low Rank Coals in Fluidized Beds: An Experimental and Theoretical Study
A New Fluidized Bed Dryer For Amorphous Slag
Upgrading of Low-Grade Coals by Heat Treatment
Dewatering and Utilization of High Moisture Brown