基于均流板原理的通风墙型植物工厂循环送风系统设计与模拟

Design and simulation of the circulating air supply system for a ventilated wall-type plant factory based on the principle of uniform flow plate

植物工厂是当前可控农业环境的最高形式之一,但植物工厂内温度、气流空间分布不均,不同栽培架之间存在一定温差、气流速度差。为解决气流植物工厂内局部环境因子差异大的问题,该研究对植物工厂进风口设置进行改进,在侧进上出气流循环模式下,借鉴均流板原理设计了一款全网孔通风墙型植物工厂,并通过计算流体力学软件(computational fluid dynamics,CFD)进行模拟,分析该类型工厂下温度、气流速度、CO_(2)浓度、相对湿度、适宜风速占比、空气龄、指定流线速度变化情况,以评价全网孔通风墙对植物工厂内局部环境差异的改进效果。该设计平均空气龄为7.5 s,是无全网孔通风墙条件下的1/9,空气更新效率有效提升。研究表明全网孔通风墙型植物工厂能有效提升植物工厂内环境因子分布均匀性。

The plant factory realizes environmental control and plant growth prediction by integrating environmental data,monitoring plant growth conditions,utilizing computers to make dynamic adjustments,and ultimately carrying out environmental control to realize the planned annual production of plants.However,its internal temperature and airflow space distribution are uneven between the two sides and the middle cultivation shelf,the same row of cultivation shelves between the different layers of shelves has a certain temperature and airflow speed difference.Airflow velocity is related to the position of the air inlet,within the direct radiation range of the air inlet,the airflow flow is intense,the airflow velocity is large,and the air exchange efficiency is high;while not in the direct radiation range of the air inlet area,the airflow flow is slow,the velocity is small,and the air exchange efficiency is low.Traditional plant factories have large differences in environmental factors,resulting in poor plant growth consistency.Therefore,the air inlet setting is the key to solving the problem of large differences in local environmental factors within the airflow plant factory.At present,most studies on airflow circulation patterns inside plant factories take the position,number,and angle of air inlets and outlets as the entry points.The effect of airflow circulation in plant factories is significantly affected by the internal structure,and it is worthwhile to study whether it is possible to improve the uniformity and stability of the distribution of environmental factors in plant factories by optimizing the airflow circulation mode and improving the internal structure.In this study,we improved the setting of the air inlet of the plant factory,designed a plant factory with a full mesh ventilating wall under the air circulation mode of side inlet and top outlet,compared the uniformity of the distribution of the environmental factors in the plant factory with and without the full mesh ventilating wall,which was simulated by computational fluid dynamics(CFD)software,and analyzed the temperature,air temperature,and air temperature in this type of plant.We analyzed the changes in temperature,airflow velocity,CO_(2) concentration,relative humidity,percentage of suitable wind speed,air age,and specified streamline velocity under this type of plant to evaluate the improvement effect of the full mesh ventilation wall on the local environmental differences in the plant factory.The full mesh ventilation wall type plant factories designed by this institute changed the original airflow trajectory,increased thermal convection,promoted greenhouse cooling,and improved temperature distribution uniformity.The full mesh ventilation wall type plant factories increased the airflow flow in the middle and lower layers,alleviated the stagnant airflow area percentage of the original structure,increased the percentage of suitable wind speed area by 20.05%compared with that of the type without a full mesh ventilation wall,and significantly improved the CO_(2) distribution uniformity in the plant factory.The relative humidity of this design is better than that of the plant factory without full mesh ventilation wall type,and the uniformity is significantly improved;the average air age of this design is only 1/9 of that of the side inlet and top outlet type,which is 7.5 s;and the air renewal efficiency is effectively improved.The study shows that the full mesh ventilation wall structure has a significant effect on the uniformity of the distribution of environmental factors in the plant factory.