单栋塑料温室内多因子综合CFD稳态模拟分析

为分析单栋塑料温室内的综合环境:气流场、温度场、湿度场、CO2浓度场,建立了包括温室内外空间、室内作物和土壤层等的温室环境几何模型。将温室内的湿空气看作水蒸气、CO2和干空气的混合气体,在分析温室中太阳辐射、作物与环境的质热交换,动量及质能传递过程的基础上,对单栋塑料温室内的环境因子进行了稳态模拟。温室内热辐射传递过程采用蒙特卡罗法模拟方法;将室内作物简化为连续固体换热模型,采用剪应力输运模型(SST)表述温室内的空气紊流。结果显示:温室通风对温度、湿度和CO2分布的影响很大,温室内部上风向温度低,湿度小,同时CO2浓度也不高;温室下风向作物冠层的环境未达到优化状态;模型的预测值低于实测值,但变化规律相似,温度、湿度、CO2含量的预测相对误差分别低于8%、6%和7%。

Three Dimensional Steady Simulation of Microclimate Pattern inside Single Plastic Greenhouse Using Computational Fluid Dynamics

o explore the microclimate factors, such as air flow, temperature, humidity and CO2 concentration inside a single span plastic greenhouse, an environmental model was established including components of greenhouse such as inner and outer space, plant and soil layer, etc. The air was assumed to be composed of dry gas, water vapor and CO2. Based on the solar radiation, mass-thermal exchange of plant-environment, transmitting process of energy and momentum of various parts, three dimensional simulation was executed to predict the pattern of temperature, humidity and CO2 concentration. The Monte Carlo method was adopted in the model of thermal-radiation transport process. Plant was simplified as continuous solid medium, and shear stress transport (SST) model was used in air turbulence analysis. The results showed that the ventilation pattern had an obvious effect on distribution of temperature, humidity and CO2 concentration. The values of temperature, humidity and CO2 concentration in upwind area were low, and the environment in downwind area was not favorable for crop growing. Generally, the predicted values were a little lower than those of the measured, while the trend was similar. The relative error values of temperature, humidity and CO2 concentration were less than 8%, 6% and 7%, respectively.