Natural energy materials and storage systems for solar dryers: State of the art

Abstract

Inappropriate food conservation practices along with insufficient and inefficient storage systems are often responsible for the deterioration in food quality of agricultural products leading to food insecurity and economic loss. Open sun drying is a well-known traditional food preservation technique but is limited in use due to its low efficiency and long drying times. Solar drying is considered the most effective, economical, green and sustainable technology available to preserve farm produce. In this regard, an attempt has been made in this study, to review the solar dryer technologies, natural energy materials and storage systems available for persevering food products and reported in detail. An extensive classification and comparative analysis of solar dryers have been presented. Evolutionary classification and performance assessment using various indicators has been carried out for solar dryers employing natural energy materials for energy storage. Polices, challenges, risks and recommendations for the improvement of existing solar dryers as well as the development of new technologies impacting the quality, economic, social and environmental aspects of solar dried products have been discussed in detail. The study concluded that solar drying processes with thermal energy storage devices based on natural materials are most preferred for delivering extended shelf life for farm produce in an energy-efficient and sustainable manner.