Enhancing the drying uniformity in solar drying systems: Computational and experimental study

Abstract

Drying is a widely used method for food preservation, but convectional drying systems are energy-intensive. Solar drying presents a sustainable and cost-effective alternative, offering significant energy savings and reduced environmental impact. However, challenges such as poor airflow uniformity and inefficiencies within the drying chamber limit its performance and product consistency. This study investigates the use of triangular and rectangular baffles, along with swirl generators, inside a drying chamber connected to a diffuser-shaped single-pass solar air heater to improve flow uniformity. While baffles are commonly used in various thermal systems and process equipment to improve flow uniformity, their application in solar dryers remains limited. Computational fluid dynamics simulations were conducted to analyze airflow patterns, identify inefficiencies in the baseline design, and assess the impact of proposed modifications. Experimental validation was also performed to evaluate the effects of baffles and swirlers on drying uniformity under varying solar radiation and ambient conditions. Results demonstrated that triangular baffles improved moisture distribution across trays, reducing the coefficient of variation (Cv) from 11.16 % to 10.26 %. Similarly, the integration of rectangular baffles lowered Cv from 12.55 % to 10.96 %, indicating enhanced uniformity in weight loss. The incorporation of a swirler further improved drying consistency, with Cv decreasing markedly from 14.95 % to 8.86 %.These findings highlights that internal airflow control elements such as baffles and swirlers effectively enhance drying performance and product consistency across trays.