侧通风口高度对塑料温室气流及温湿度的影响

Effect of side vent height on airflow,temperature and humidity in plastic greenhouse

为确定降温、除湿等不同环境需求下温室最适侧通风口高度,以陕西省杨凌地区的塑料温室为对象,采用试验和计算流体力学模拟方法,对4种侧通风口高度(40、60、80和100cm)下室内的流场、气温、相对湿度变化及分布均匀性进行研究;模型经过实测验证,模拟值与实测值变化趋势基本吻合,各测点气温和相对湿度的平均相对误差分别为1.2%和2.0%。数值模拟结果表明:不同侧通风口高度的室内平均风速由高到低依次为距地面60、40、80和100cm;温湿度瞬时变化速率随通风口高度升高呈先升高再降低的趋势;侧通风口距地面100cm时,室内的温湿度均匀性最优,60cm的次之,27个测点的温湿度变异系数较同时刻100cm高度仅高出1.1%和3.0%;综合考虑降温及除湿需求,侧通风口距地面60cm时室内气流运动活跃,适合夏季降温排湿和换气补气;在距地面60cm基础上提高侧通风口高度,可在保证除湿效果的同时减缓降温速度,适合冬季保温排湿;降低侧通风口距地高度可减缓室内环境变化速率,适合极端天气下的通风换气需求。

In order to determine the optimum side vent height of the greenhouse under different environmental requirements such as cooling,dehumidification and ventilation,four heights of side vents,40,60,80 and 100 cm,were designed in greenhouse in Yangling,Shaanxi Province.The experimental measurement and computational fluid dynamics simulation technology were applied to research the effects of vent height on variation and distribution of indoor flow field,temperature,relative humidity.The model was verified by actual measurement.The results show that:The simulation values of model are consistent with the variation trend of measured values,and the average relative errors are 1.2% and 2.0%,respectively;The numerical simulation results show the average indoor wind speed with different vent heights are ranked from high to low is 60,40,80 and 100 cm;The instantaneous change rate of temperature and humidity increases first and then decreases with the increase of vent height;The side vent of 100 cm is the best in distribution uniformity,followed by 60 cm,the variation coefficient of temperature and humidity at 27 sites was only1.1% and 3.0% higher than that of 100 cm;Considering the cooling and dehumidification requirements of ventilation,indoor air flow is active when the side vent is 60 cm from the ground,which is suitable for cooling and dehumidification in summer;Moreover,the vent height can be increased on the basis of 60 cm to slow down the cooling speed while ensuring the dehumidification effect,which is suitable for the heat preservation and moisture drainage in winter;Reducing the vent height can slow down the rate of environment change,which is suitable for ventilation demand in extreme weather.