Current status of solar-assisted greenhouse drying systems for drying industry (food materials and agricultural crops)

Abstract

Abstract Solar energy has long been utilised in crop conservation. The use of solar dryers as a drying method overcomes the drawbacks of the traditional approach to drying crops under the sun. Previous studies were coherently described and focused on the development and thermal convection of greenhouse dryers, structural analysis, crops cultivation for offering choices to reader about solar greenhouse dryers in agriculture. Based on the previous related studies, the current work proposes an evolve and detail review of solar-assisted greenhouse dryers, namely, passive dryers, active dryers and hybrid dryers, from the aspects of system performance, collector performance and the drying characteristics of various crops. Drying crops in a solar greenhouse dryer protects crops from insects, rain and dust. Thus, these dryers are preferred in natural and conventional drying. This review provides a satisfactory guide for researchers to compare, develop and improve solar greenhouse drying systems to achieve optimum crop drying rates based on thermal convection mode.