×
The submission system is temporarily under maintenance. Please send your manuscripts to
Go to Editorial ManagerThe conventional open sun drying is not efficient, it is slow and contaminated and there is a necessity to develop highly advanced technologies in solar drying. The review looks critically at solar dryers that are improved with concentrator, optical, thermal energy storage (TES) or phase-change materials (PCM). The incorporation of parabolic trough or compound parabolic concentrators leads to a high temperature of over 100-115 oC and a thermal efficiency of up to 88 %. Reflective walls are also made to enhance optical capturing by up to 37.6 %, and shorten drying time by 15-20 %. TES/PCM systems increase the operation of TES systems beyond the sunset, nano-enhanced PCMs reduce drying time by 40% and enhance thermal efficiency by more than 48%. These systems demonstrate short payback periods (0.43-5.14 years) with regard to economics. They minimise the emission of CO2 by 2-44 tons/ lifetime of systems. These combined technologies have addressed intermittency and low efficiency and enabled solar drying to be a reliable and cost-effective and sustainable solution, as the UN Sustainable Development Goals of clean energy and climate action suggest.