亚洲一区欧美在线,日韩欧美视频免费观看,色戒的三场床戏分别是在几段,欧美日韩国产在线人成

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 Qf) is defied with the soil temperature more than 15℃ at 20cm 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 2.4~2.8m. 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.