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

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, CO₂ 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 CO₂ 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.