College of Engineering, Shenyang Agricultural University, Shenyang, China.
National & Local Joint Engineering Research Center of Northern Horticultural Facilities Design & Application Technology (Liaoning), Shenyang, China.
PLoS One. 2020 Sep 29;15(9):e0239851. doi: 10.1371/journal.pone.0239851. eCollection 2020.
Natural ventilation is an effective energy-saving strategy conducive to promoting sustainable agricultural production. A comprehensive numerical simulation is performed to predict the airflow pattern and thermal behavior in different arched greenhouses. The defined arc chord angle and position angle are employed to examine the natural ventilation process and corresponding roof vent scenarios. The numerical simulation is compared with the experimental data and good agreements are observed. Various configurations of ventilated structures, wind conditions and ventilation layouts are simulated on a high-resolution polyhedral grid based on a grid sensitivity analysis, which is beneficial to the optimization of greenhouse cooling combined with the water circulation heat collection system. The cooling effect in summer is analyzed by estimating the ventilation flow rate and microclimate inhomogeneity. The results demonstrate that the position angle of 85° of the arched greenhouses is an optimum ventilation direction and its impact on the microclimate is marginally affected by the change of the ventilation structure. The designed ventilation scheme has perfect air exchange capacity and cooling effect because the average air temperature can be reduced by 1.5°C more than the existing greenhouse in 10 minutes of ventilation. Likewise, the results show that the temperature and velocity inhomogeneities are approximately decreased by 33.3% and 11.89%, respectively. The practical value of the research is expected to provide basic quantitative conclusions for evaluating the natural ventilation performance.
自然通风是一种有利于促进可持续农业生产的节能策略。通过全面的数值模拟，预测了不同拱形温室中的气流模式和热行为。采用定义的拱弦角和位置角来检查自然通风过程和相应的屋顶通风情况。将数值模拟与实验数据进行比较，观察到良好的一致性。基于网格灵敏度分析，在高分辨率多面体网格上模拟了各种通风结构、风况和通风布局，这有利于与水循环集热系统相结合的温室冷却优化。通过估算通风流量和小气候不均匀性来分析夏季的冷却效果。结果表明，拱形温室的位置角为 85°时是最佳通风方向，其对小气候的影响受通风结构变化的影响很小。由于通风 10 分钟后平均空气温度可降低 1.5°C，因此设计的通风方案具有完美的空气交换能力和冷却效果。同样，结果表明温度和速度不均匀性分别降低了约 33.3%和 11.89%。研究的实际价值有望为评估自然通风性能提供基本的定量结论。
