The effect of spire width on microclimate within Venlo-type greenhouses

Abstract

【Objective】 The Venlo-type greenhouse is commonly used in commercial horticulture due to its efficient space utilization and superior light transmission. This study investigates the impact of spire width on microclimate within such greenhouses under natural ventilation conditions. 【Method】 The study focused on multi-span glass greenhouses. We used experimental measurement and CFD modelling to simulate the variations in temperature and airflow in the greenhouse for various spire widths: 3.2 m JD3.2, 3.6 m JD3.6 and 4 m JD4 under natural ventilation conditions when the outdoor wind speed was 0 and 1 m/s, respectively. 【Result】 ① Comparing with measured temperature at different sampling points in the greenhouse reveals that the relative error of the simulated temperature ranged from 0.2% to 3.3%, ② Spire width had a significant effect on temperature distribution in the greenhouse. In particular, temperature increased upward in the greenhouses with the JD3.2 spire, while, in contrast, temperature increased downward in the greenhouses with the JD3.6 spire. ③ Regardless of the outdoor wind speed, greenhouses with JD3.2 spire had the best heat removal efficiency. The heat removal efficiency of JD3.6 and JD4 spire and the associated temperature distribution in the greenhouses was better when the outdoor speed was 0 m/s than when the outdoor wind speed was 1 m/s. 【Conclusion】 For all spire widths we compared under different working conditions, the greenhouse with JD3.2 spire work best for ventilating and cooling the greenhouse.

Keywords

• venlo type greenhouse
• spire width
• natural ventilation
• numeral calculations