主动式温室地暖系统温控效果仿真与试验

Simulation Analysis and Field Testing of Active Greenhouse Heating System

针对严寒天气影响温室内作物生长的问题,提出了一种主动式温室地暖系统,并基于热平衡理论,首先对地暖系统的热量传递过程进行了研究,分别建立了温控系统径向、轴向传热数学分析模型;再利用有限元分析软件进行了二维稳态温度分布状态的数值模拟,研究结果表明,若将距地面20 cm处土地温度大于15℃作为地暖系统的有效作业范围(简称Q_f),地暖系统的开启温度应不低于28℃,且系统入风口温度每增加2℃,其轴向有效作业辐射范围可扩大2.4~2.8 m;通过与昌平区马池口温室大棚实地试验的数据对比,地暖系统换热过程对浅层与深层土壤温度扰动规律与理论分析结果一致,进一步验证了仿真分析的有效性。

This paper proposed an active greenhouse heating system which focuses on the influence of crop growth under extreme cold weather.At the beginning,the heat transfer process of heating system was analyzed based on thermal equilibrium theory.The temperature control system models were established based on radial and axial heat conduction mathematical analyses respectively.Then,the numerical simulation of two dimensional steady temperature distribution was carried out by means of finite element method(FEM) software.The simulation result indicates the control parameters in the greenhouse.When the effective operation range(later referred to as Q_f) is defied with the soil temperature more than 15℃ at 20 cm underground,the temperature of heating system should be opened no less than 28℃.The kinetics is changed in terms of the temperature dependence.If the air intake temperature of heating system is raised by 2℃,the axial effective operating range extends by 2.4 ~2.8 m.Later,field test was conducted in greenhouses located in Changping District,Beijing.Compared with simulation data,the field testing data shows that the perturbation law of heating system heat transfer process on shallow and deep layer soil temperature is consistent with theoretical analysis.The simulation parameters could help to guide the greenhouse control.