Recent Advancements in Design, Application, and Simulation Studies of Hybrid Solar Drying Technology

Hybrid solar drying technology for food products is a clean and cost-effective replacement of highly energy intensive thermal dryers employed in agri-food processing chain. This involves the amalgamation of "only solar dryer" with various other energy harvesting systems like, biogas, heat pump, and thermal storage materials. This paper reviews the significance of hybrid solar dryers in terms of withstanding varied climatic and uncontrolled environmental conditions and their impact on drying characteristics of food products. From the appraisal, heat pump hybrid solar dryers proved to be more efficient, having wide range of drying temperature, and is suitable for heat-sensitive products. On the other hand, the advantages of biomass hybrid solar dryer lies in its ability to utilize cheap local resources for assisting the energy requirements and have low constructional cost. However, the state of art indicated that sanitary aspects of solar drying have not been explored much and should be encouraged. The presented review also explores the research scenario of relevant virtual platforms, applicable for simulating the dryer design and drying parameters. The important findings on modeling aspects of dryer design and thick layer drying of food products in solar dryer are also discussed. The economic assessment of presently available hybrid solar dryers showed competitive profitability metrics and equipment cost. Moreover, it is suggested for the promotion of energy-efficient hybrid solar dryers and its environmental benefits in the future to provide a benchmark for drying applications in food processing industries.