Modular Solar Drying and Thermal Energy Storage System Configuration Assessment

Solar drying is an effective method for preserving food and enhancing its characteristics by removing moisture using ambient air and elevated temperatures. This technology, made for harnessing solar energy, offers a sustainable alternative to conventional drying methods, reducing the consumption of fossil fuels. This study investigates the configuration of a solar drying system for kiwi slices, based on flat plate collector (FPC) combined with packed bed thermal energy storage (PBTES) using copper slag as the storage medium. The research assesses both unidirectional and bidirectional configurations of the storage unit flow to determine the effect on the drying process. The analysis is supported on experimental validation of the thermal models for the FPC and PBTES unit, along with the calibration of the drying model using existing data. Results indicate that unidirectional flow provides better outcomes with smaller storage volumes, whereas bidirectional flow may offer superior performance with larger storage volumes. The maximum plant factor obtained was 93.3% for the bidirectional configuration with a solar field size of 10 m2 and storage volume of 3141 lt. A careful calibration of the thermal system is necessary to avoid suboptimal configurations that either underutilize solar energy or risk overheating the product. The use of a bidirectional configuration with solar heat could lead to a better process performance without the need for external heating.