Study on the discharge coefficient of wind-driven naturally ventilated Chinese solar greenhouses

文献类型： 外文期刊

第一作者： Zhang, Jingfu

作者： Zhang, Jingfu;Zhao, Shumei;Li, Youyu;Fan, Zilong;Ding, Tao;Liu, Zhiwei;Li, Yanfeng

作者机构：

关键词： Chinese solar greenhouse; discharge coefficient; area ratio; position height; wind direction; altitude

期刊名称：BUILDING SIMULATION （ 影响因子：5.9； 五年影响因子：5.1 ）

ISSN： 1996-3599

年卷期： 2024 年 17 卷 9 期

页码：

收录情况： SCI

摘要： The Chinese solar greenhouse (CSG) is a prevalent feature in agricultural practices within China. Nevertheless, the regulation of natural ventilation within this architectural structure remains suboptimal. Consequently, the development of a natural ventilation model becomes imperative for the effective management of the greenhouse environment. Of particular significance within these models is the consideration of the discharge coefficient as a pivotal parameter. Conducting a multi-case investigation into the variable-dependent discharge coefficient is crucial for both practical application and model advancement. This research delved into the impact of various factors, including the upper-lower vents area ratio (Aup/Alow), vent-greenhouse area ratio (Alow/Agreenhouse), lower vent position height (h/H), the incident angle of the external wind, and altitude, on the discharge coefficient (Cd) of CSG. A CFD model was developed for a scaled CSG with validation conducted through field experiments and wind tunnel tests. Results indicated a 61.6% reduction in Cd on average corresponding to an 80% decrease in Aup/Alow. Cd levels remained consistent following the attainment of an Aup/Alow ratio of 1.0. Besides, there was an average increase of 52.5% in Cd levels for every 0.09 decline in h/H, attributed to the blocking effect of the cover. Moreover, the ventilation rate and the pressure coefficient difference were utilized to construct a model of Cd pertaining to greenhouse design and ventilation operation, exhibiting a notable accuracy level of R2 = 0.95. Furthermore, the blocking effect of higher h/H was relieved as the incident angle theta decreased under the windward conditions. The increase in Aup/Alow and the decrease in Alow/Agreenhouse were identified as crucial factors contributing to the growth of Cd under leeward conditions. Ultimately, the high-altitude environment led to a rise in Cd levels in contrast to the low-altitude region. The increasing rate of Cd correlated positively with Alow/Agreenhouse and h/H initially, but exhibited a decline once Alow/Agreenhouse reached 0.036, remaining stable thereafter once h/H reached 0.18. In summary, a comprehensive examination of the discharge coefficient of CSG was undertaken, addressing a significant knowledge deficiency and laying the groundwork for advancements in the natural ventilation model and the intelligent control system for CSG.

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