Recent advancements in indirect solar dryer performance and the associated thermal energy storage

Drying is a fundamental process for preserving agricultural products, involving heat and mass exchanges. As a sustainable selection, researchers are focusing on solar dryers to improve drying efficiency, shorten drying times, and maintain product quality. Indirect type solar dryers (ITSD) have shown promise in post-harvest preservation. However, there is a lack of detailed investigation in their unique features, types, and performance-enhancement techniques. Thermal energy storage methods, which store excess energy for times when there is no solar irradiance, can improve the dependability of solar drying. Expensive experimental setups have led to the use of computer simulation techniques like computational fluid dynamics (CFD) to optimize drying conditions and dryer design while maintaining product quality. The review aims to provide an overview of different ITSD designs, techniques of thermal energy storage, and explore the use of CFD in analyzing heat and mass transfer phenomena in indirect solar drying systems. Additionally, this review study inspires researchers to explore the development of indirect solar dryers suitable for various drying environments, diverse product drying capacities, and different drying durations. Further research and development in these areas will continue to enhance the performance, energy efficiency, and scalability of indirect solar dryers, contributing to sustainable agriculture and energy conservation. • Introduction of current technologies for indirect solar drying. • The different features, types, and methods for improving performance of indirect-type solar dryers are discussed. • CFD methods for improving drying conditions and designing indirect solar dryers are examined. • TES techniques and enhancements and the integration of indirect solar dryers are investigated. • The future research potential and challenges for indirect-type solar dryers are discussed.