CFD based airflow uniformity optimization of Chinese solar greenhouses with long-row cultivation: Impact of unit layout design

The inherent conflict between thermal insulation and optimal airflow distribution presents a critical challenge in Chinese solar greenhouses (CSGs) during winter production. This study develops an innovative computational fluid dynamics (CFD) prediction model to optimize fan-coil unit (FCU) installation parameters under long-row cultivation conditions, aiming to enhance airflow velocity and uniformity within crop canopies. Experimental validation confirmed the reliability of the numerical model across different crop height scenarios. The results demonstrated that for lower crop heights (1.0 m), the unit optimal interval and installation height were 1.5 m and 2.0 m, the optimal tilt and swing angles were 10° and 30°, respectively; while for higher crop heights (1.6 m), the unit optimal interval and installation height were all 2.0 m, the optimal swing angle was 10°. The airflow velocity and temperature distribution uniformity improved by 33.33 %, 24.07 % (1.0 m) and 23.05 %, 45.06 % (1.6 m), respectively. The proposed methodology provides actionable guidelines for FCU system design while establishing a theoretical basis for both environmental optimization and mechanization development in CSG operations.