Research advances in solar dryer technologies integrated with solar air heater: a state-of-the art review on design variations, performance and feasibility assessments

This paper presents a comprehensive review of the most significant and recent technologies that have been integrated with solar dryers, demonstrating a notable enhancement in the performance of solar dryers. The majority of review articles in this field that have been published have concentrated on the application of solar drying for food preservation in agricultural industries. Numerous researchers have found gaps at the component level and suggested different modifications to solar thermal collectors to enhance drying efficiency. Various technologies that have been created and put into use have effectively and efficiently optimized the energy requirements. Nevertheless, there are not many studies that concentrate on the possible integration strategies in different industries where drying is a crucial step in the production process. This study presents a comprehensive overview of the key drying processes used in different industries to provide readers a sense of the current status of existing technologies and the on-going research being done in the topic of sun drying. To develop innovative drying systems for large-scale enterprises that can be used to other industrial settings, it has been suggested that solar drying be integrated with the current drying techniques. This paper discusses how solar energy is used in the food sector, with a focus on solar air heaters and how they are integrated into solar drying processes. This will help industries and researchers make the drying process compatible with solar energy. This study also offers an alternative viewpoint by examining and contrasting solar dryers based on the many designs that are employed, as well as strategies to increase the solar dryer's efficiency, shorten its drying time, and improve its overall performance. Additionally, this study shows how various solar drying methods such as using gravel, sand, paraffin wax, etc. affect the rate at which moisture is removed based on sensible and latent heating.