A self-driven solar air heater integrated with a thermal energy storage unit: Design and experiment study

The Self-driven solar air heater (SDSAH) can operate independently without reliance on an external power grid through the incorporation of photovoltaic (PV) panels, however it is still subject to intermittent operation and large temperature fluctuations. In this study, a novel SDSAH integrated with a thermal energy storage (TES) unit was proposed and the operational thermal and electrical performance of the SDSAH with TES unit were experimentally investigated. The results showed that the SDSAH could output heat continuously throughout the day (24 h) in a self-sustaining mode and automatically adjust the airflow rate according to solar irradiance. The overall thermal efficiency of this system averages at 52.73 % throughout the day. The introduction of the TES unit could lower the peak temperature of the outlet air by more than 9 K and improve the electrical efficiency of PV panels. However, due to heat loss at night, the whole-day thermal efficiency will be slightly lower than that of SDSAH without a TES unit. The energy payback time for this system was 42 months. This study offers new ideas and solutions for a distributed agricultural drying system.