不同遮阳工况下温室作物冠层辐射场与温度场的CFD分析

Analysis of Canopy Radiation and Temperature Field in Greenhouse under Different Shading Conditions Based on CFD

为研究不同类型遮阳网对温室作物冠层辐射场与温度场的影响,采用标准k-ε湍流模型和DO模型建立了温室作物冠层辐射对流换热的CFD模型,采用辐射折算的方法模拟外遮阳对室内环境的影响。将模型计算的辐射和温度值与试验实测值进行对比,辐射值平均误差为18. 8%,温度值的相对误差为3. 9%。利用建立的温室CFD模型,对不同遮阳率的遮阳网下温室作物冠层辐射场与温度场进行分析,结果表明:一层遮阳网温室内降温明显;比对一层遮阳网工况,开启两层遮阳网时室内降温幅度增加并不明显,且辐射值偏低。在此基础上,改变了遮阳网遮阳率,发现在其他条件相同的情况下,开启遮阳率为65%的遮阳网相比遮阳率43%的遮阳网温室内辐射减少40W/m^2,室内温度相对降低0. 8℃。此模型可为基于作物光温需求的遮阳调控方案提供仿真计算分析。

In order to study the effects of different types of shading nets on the canopy radiation field and temperature field of greenhouse crops,the CFD model of crop canopy radiation convective heat transfer was established using the standard k-ε turbulence and DO model,considering the influence of external shading on indoor environment by radiative conversion method. The radiation and temperature values of the model were compared with the experimental values. The average error of the radiation value was 18. 8%,and the relative error of the temperature value was 3. 9%. Using the established CFD model,the canopy radiation field and temperature field of the crop under shaded nets under test conditions and different shading rates showed that the temperature in the greenhouse was significantly reduced by one layer of shading net;the temperature drop of the two shading nets was not obvious,and The radiation value is low. Based on this,the sunshade net shading rate was changed. It was found that in addition to the same shading rate and other conditions,the shading rate was 65%. The shading rate was 43%. The shading rate was 43%. Shade nets reduced the radiation in the greenhouse by 40 W/m^2,reduce the indoor temperature by more than 0. 8℃. This model can provide simulation calculation and analysis for shading control scheme based on crop light and temperature requirements.