Design of an Air-Fed PTC Solar Field Integrated With a Rock Bed-Based Thermal Energy Storage System

Integrating solar energy to provide heat for industrial processes represents a viable solution aligned with the ongoing energy transition. Parabolic trough collectors (PTCs) are a reliable and mature technology within this context. This study addresses the performance of an industrial air-drying plant integrated with a PTC solar field and a thermal energy storage (TES) system comprising two rock beds operating in parallel. To improve the exploitation of solar radiation, pressurized air was used as the heat transfer fluid for the PTC due to its high temperature limits. A parametric analysis was conducted to evaluate the impact of solar field size on performance, varying both the number of modules in series per string and the number of parallel strings. Results show that the solar fraction (SF) increases with the number of parallel strings, while increasing the number of series modules initially raises the SF to a peak before slightly decreasing. The maximum SF achieved was 85% with a TES volume of 96.24 m³ and a solar field comprising 12 modules in series and 4 parallel strings, resulting in a total collection area of 3450 m².