Moreover, Responding Heat Loss Was Less

School of Electronic Information and Electrical Engineering, Shanghai Jiao Tong University, Shanghai 200240, China 2. Institute of Crop Science, Chinese Academy of Agricultural Sciences, Beijing 100081 , China 3. Sunqiao Modern Agricultural Development Zone, Shanghai 201210, China) 机构地区:[1]上海交通大学电子信息与电气工程学院,上海200240; [2]中国农业科学院作物科学研究所,北京100081; [3]上海孙桥现代农业园区,上海201210 出  处:《农业机械学报》 EI CAS CSCD 2012年第43卷第11期 186-191页,共6页 《Transactions of the Chinese Society of Agricultural Machinery》 基  金:上海市科技兴农重点攻关项目(沪农科攻字(2009)第8-1号) 摘  要:连栋塑料温室主要依靠日光蓄热,冬季为保温需要长时间密闭以避免室内热量流失,这就导致室内形成高湿环境,使栽培作物易患病虫害。以有效除湿和减小室内热量损失为目标,以十一连栋塑料温室为研究对象,建立全尺度计算流体力学模型(CFD模型)。在顶窗通风工况下,CFD模型的有效性经实验数据验证,其计算值与各测点湿度的实验值变化趋势吻合,且差异在5%以内;并利用该模型研究了不同开窗组合(侧窗、顶窗和顶窗加侧窗)对温室内空气流场和湿度场的影响。仿真结果表明,顶窗通风是一种较理想的通风组合,能够在3min内完成作物冠状层的除湿。除湿结束后,室内平均相对湿度从92%降至68%,湿度分布均衡性较好,且热损失较小,能满足冬季温室保温、除湿的要求。 Multi-span plastic greenhouses mainly depend on solar heat storage. In winter, greenhouse is closed for prolonged periods for thermal insulation to avoid indoor heat being lost. Therefore, this would lead to indoor high humidity and consequently the occurrence of crop diseases. For making a good compromise between dehumidification effectiveness and indoor heat loss prevention, a full-scale computational fluid dynamics (CFD) model was developed based on an 11-span plastic greenhouse. Firstly, the model was validated by comparing experimental humidity with CFD simulations under roof ventilation. CFD simulations had similar trends to those of the experiments, with less than 5% difference. Then, the validated model was used to investigate the influences of vent configurations (i. e. side, roof and side plus roof) on the airflow pattern and humidity field inside the greenhouse. Simulations showed that roof ventilation tended to be the best. With the roof ventilation, dehumidification in the crop canopy could be achieved in 3 min. After dehumidification, relative humidity was reduced from 92% to 68% and indoor humidity homogeneity was good. Moreover, responding heat loss was less. Therefore, this ventilation mode is able to meet the requirements of thermal insulation and dehumidification under winter climate conditions.



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