Solar drying Technologies: A review and future research directions with a focus on agroindustrial applications in medium and large scale

Abstract

• Design, integration schemes, and economic analysis of Solar Dryer were discussed. • The most important works about industrial Solar Dryer were classified and tabulated. • The current state of the art and future development of Solar Dryers were presented. • Loads greater than 90 kg of fresh food or solar collection areas greater than 30 m 2 was analyzed. • Industrial drying literature was reviewed to identify opportunities for integrating solar thermal technologies. The food industry accounts for approximately 30% of global energy consumption. In addition, food-processing activities contribute almost 26% of total greenhouse gas emissions. Dehydration is an energy-intensive unit operation, and most foods require drying, at least partially, at some stage of processing. Solar food drying can help sustainable energy supply and contributes to the solution of environmental degradation problems. This review focuses on medium and large-capacity solar drying systems, some challenges for their implementation in the agro-industrial sector, and the analysis of the integration schemes of solar thermal systems to the most common drying processes in the agroindustry. A systematic information search was carried out by analyzing four reviews on industrial solar drying and more than 50 articles on medium to large scale solar food drying (i.e., fresh product load greater than 90 kg or solar collection area greater than 30 m 2 ); from 1991 to date. The solar technology with thermal convection systems is mature for industrial food drying on an industrial and semi-industrial scale. There is a niche opportunity to produce industrial size systems for small and medium producers, which can incorporate added value to their production.