日光温室墙体一维导热的MATLAB模拟与热流分析

为探明日光温室墙体层间温度变化及热量传递动态规律,采用有限差分法建立墙体一维非稳态导热模型,利用MATLAB编制相应的模拟程序,计算出日光温室墙体各点的温度和热流。结果表明:该模型能够比较准确模拟日光温室土墙的温度。墙体内侧存在有效蓄热层,它对日光温室室内热环境有积极的作用。墙体有效蓄热层的热流白天指向墙体外侧,夜间指向墙体内侧,因此它的厚度直接根据热流的方向确定。有效蓄热层与天气、墙体总厚度以及墙体热特性参数有关。2012-12—2013-01期间有效蓄热层厚度为0.26~0.45m不等,最大值出现在连续雪天。同时从理论上验证了3.0m厚的温室土墙内部存在热流相对稳定的"热稳定层"。

MATLAB simulation of one-dimensional heat transfer and heat flux analysis of north wall in Chinese solar greenhouse

To explore the changes of temperature and heat transfer characteristic in the north wall layer of the Chinese solar greenhouse, a one-dimensional difference model for unsteady heat transfer of wall was established.By the corresponding computer program with MATLAB, the temperature and the heat flux of any point in the wall at any time could be obtained.The analysis showed that the simulation model could accurately estimate the temperature of soil north wall in solar greenhouse.The effective heat storage layer existed in the inner surface of wall, which played a positive role on indoor thermal environment of solar greenhouse.As the heat flux of the effective heat storage layer was from the indoor to the outdoor during the day, and was from the outdoor to the indoor at night, the thickness of the layer was determined by the direction of heat flux.The effective heat storage layer was associated with the weather, the total thickness of wall and thermo physical properties of the wall material.The thickness of the storage layer that calculated in certain cases was from 0.26 to 0.45 m.A maximum value appeared on a continuous snowy day.In addition, it theoretically verified the existence of a thermal-stable layer inside 3 m soil wall whose heat flux was relatively constant in the solar greenhouse.