Thermal performance and environmental assessment of a hybrid solar-electrical wood dryer integrated with Photovoltaic/Thermal air collector and heat recovery system

Improving the energy efficiency of the drying industry is considered as one of the most efficient and promising ways for reducing carbon emissions from the industrial sector. In this context, the present work is aimed at investigating numerically the thermal performance and the environmental impact of a novel forced-air convection hybrid dryer for wood drying industry under realistic environmental conditions. The proposed dryer system consists mainly of a Photovoltaic/Thermal (PVT) solar air collector for thermal and electrical energy production, an insulated drying chamber, an air-to-air heat recovery system and fans. To simulate the functioning of the dryer system, a transient model based on energy and mass equations is developed and validated with experimental data. Annual dynamic simulations were carried out under weather conditions of the Ajaccio city and the effect of recovering waste heat from the dryer unit during both solar drying and hybrid drying processes was presented and analyzed. Results show that using the heat recovery system with an effectiveness of 0.8 leads to reduce the solar drying time by about 40% in summer and up to 32% in winter. For hybrid drying functioning, integrating of both heat recovery system and PVT air collector reduces the energy consumption of conventional dryer up to 86.5% during summer and up to 73.5% during winter. Finally, it was shown that the proposed hybrid wood dryer with PVT air collector and heat recovery system is suitable for wood drying industry and leads to improve the energy efficiency of conventional dryers and to reduce annually the amount of CO2 emissions up to 78.5%.