Drying of solids is one of the most common, complex, and energy-intensive industrial processes. Conventional dryers offer limited opportunities to increase energy efficiency. Heat pump dryers are more energy and cost effective, as they can recycle drying thermal energy and reduce CO2, particulate, and VOC emissions due to drying. This book provides an introduction to the technology and current best practices and aims to increase the successful industrial implementation of heat pump- assisted dryers. It enables the reader to engage confidently with the technology and provides a wealth of information on theories, current practices, and future directions of the technology. It emphasizes several new design concepts and operating and control strategies, which can be applied to improve the economic and environmental efficiency of the drying process. It answers questions about risks, advantages vs. disadvantages, and impediments and offers solutions to current problems.Discusses heat pump technology in general and its present and future challenges.Describes interesting and promising innovations in drying food, agricultural, and wood products with various heat pump technologies.Treats several technical aspects, from modeling and simulation of drying processes to industrial applications.Emphasizes new design concepts and operating and control strategies to improve the efficiency of the drying process.