Computational fluid dynamics-based optimization of inclined slotted solar drying chamber for enhanced Citrus hystrix drying: Experimental validation and numerical analysis

A uniform temperature distribution optimizes the energy efficiency and operational costs of solar drying processes. However, existing solar drying chamber designs often suffer from non-uniform heat distribution and extended drying times, limiting their industrial applicability. This study introduces novel inclined slotted solar drying chamber (ISSDC) configurations and investigates their performance through computational fluid dynamics (CFD) simulations and experimental validation. Six configurations were analyzed: the ISSDC with inclination angles of 90°, 67.5°, 45°, and 22.5°, a perforated-type solar drying chamber (PTSDC), and a cylindrical-type solar drying chamber (CTSDC). The study employed a hybrid solar drying system incorporating cross-matrix absorbers and auxiliary heating, operating at an air velocity of 2.0 m/s. The performance was evaluated using temperature distribution mapping, pressure drop analysis, and drying kinetics of Citrus hystrix leaves. The ISSDC 67.5° configuration demonstrated superior performance, achieving a 30% reduction in drying time (280 min versus 385–390 min for conventional designs) and the lowest specific energy consumption (SEC) of 3.17 kWh.kg⁻¹. This configuration maintained optimal temperature uniformity (52.59 °C average) and exhibited reduced pressure variations (90–290 Pa) compared to conventional designs (300–400 Pa). CFD simulations revealed that the inclined slots generated beneficial swirling flow patterns, enhancing heat transfer and eliminating dead zones within the chamber. The novel ISSDC 67.5° design significantly improved the drying efficiency through optimized airflow patterns and enhanced temperature uniformity.