Recent advancements in solar drying: Role of absorber plate geometry, PCM thermal enhancement, and encapsulation for improved energy storage and drying efficiency

Solar drying systems play a key role in sustainable food and agricultural processing by employing renewable energy sources for effective moisture deduction. This review work systematically investigates the impact of absorber plate modifications, nano-augmented phase change materials (NAPCM), and encapsulation approaches on the thermal performance of direct and indirect solar drying systems. Several surface-modified absorber plates, including pin fins, baffles, jet impingement, and roughened, coated, and geometrically modified surfaces, are analyzed for their role in enhancing heat absorption, turbulence, and heat transfer efficiency. The incorporation of NAPCM enhances latent heat storage, thermal conductivity, and heat retention, confirming stable drying conditions even during intermittent solar radiation. Encapsulation techniques are explored for their effectiveness in advancing PCM durability, curtailing subcooling, and boosting thermal energy storage. Moreover, energy and exergy analyses evaluate system efficiency, exergy destruction, and entropy generation. Environmental effect assessment emphasizes the potential for reducing carbon emissions and energy consumption, while an economic analysis provides insights into the economic viability of integrating NAPCM into solar drying systems. It is found that the drying of vegetables and meats benefits from PCM and sensible storage materials, maintaining temperatures between 50 and 90 °C for optimal drying. Future research should focus on augmenting encapsulation techniques to prevent nanoparticle leakage, improve the long-term stability of PCMs, and explore low-cost manufacturing techniques for large-scale commercial adoption. The integration of these advanced technologies has the potential to significantly enhance the sustainability of solar drying systems, offering a pathway toward energy-efficient drying solutions for agricultural and industrial applications.