Gas-solid flows are involved in numerous industrial processes and occur in various natural phenomena. This authoritative book addresses the fundamental principles that govern gas-solid flows and the application of these principles to various gas-solid flow systems. The book is arranged in two parts: Part I deals with basic relationships and phenomena, including particle size and properties, collision mechanics, momentum transfer, heat and mass transfer, basic equations, and intrinsic phenomena in gas-solid flows. Part II discusses gas-solid flow systems of industrial interest such as gas-solid separators, hoppers and standpipes, dense-phase fluidised beds, fluidised beds, pneumatic conveying systems, and heat and mass transfer in fluidisation systems. As a comprehensive text on gas-solid flows, including end-of-chapter problems, this book is aimed at graduate students, but will also be useful to a broad range of engineers and applied scientists.