Heat Pump Drying: Recent Developments and Future Trends

This review paper focuses on the recent progress made in heat pump drying (HPD). An introduction is given on the operating and working principle of the heat pump drying system. Advantages and limitations of HPD are outlined. Two industrial applications of HPD, food and timber, are discussed. New developments in HPD are presented. A section discussing the potential of incorporating advanced heat pump cycles for drying application is also presented. Some possible new hybrid HPD technologies, e.g., radio frequency and infrared assisted HPD are discussed in terms of their industrial potential. Opportunities for further R&D to achieve better product quality and energy efficiency are identified. A new heat pump dryer design is also described to demonstrate the new trend in versatile heat pump design.