Integrating a phase change material based thermal energy storage system with a solar vacuum timber dryer

This study focused on the development of a solar-heated vacuum dryer with a thermal-energy storage system. The timbers layers were stacked between specially fabricated aluminum platens, integrated with sealed tubes filled with phase-change material (PCM) for thermal storage. Each platen had openings in both the ends to allow hot water enter from one end and exit through another end. An evacuated tube collector (ETC)-based solar hot-water system was used to heat the water, and the hot water was flown through the platens for melting and charging of the PCM inside the tubes. The platens, along with the wood layers, were placed in a vacuum tank. During the day, the heating of wood and the melting of PCM were done simultaneously, while in night time, wood layers got heated through conduction using stored heat in the platens. Two 38 mm thick hardwoods (Populus deltoides and Mangifera indica) were dried in January, the coldest month in India. Moisture content of Populus deltoides (initial moisture content of 110%) and Mangifera indica (initial moisture content of 95%) dropped to the final moisture content of 14% in nine days of the drying with an average moisture content drop of of 10.7%/day and 8.9% perday, respectively.