兰州地区日光温室北墙体长度变化对温室热环境的影响

Effect of North Wall Length Variation of Greenhouse on Thermal Environment of Solar Greenhouse in Lanzhou

以兰州地区日光温室为研究对象,建立了日光温室模型,并对该模型进行了试验验证,以北墙体阴影率和温室日放/蓄热量比值以及累积日有效积温等为评价指标,分析了不同天气条件下温室长度变化对温室内热环境的影响,以期探究日光温室北墙体长度的变化对温室热环境的影响。结果表明:日光温室东墙和西墙在北墙会造成阴影,以13:00时为中心呈对称的关系,保温被开启与关闭时刻的阴影率最大,随着温室墙体长度的增加,其阴影率逐渐减小。在改变温室北墙体长度,而温室其它结构参数保持不变的条件下,兰州地区日光温室的日放/蓄热量比值与太阳辐射强度及北墙体长度呈非线性关系;当日放热量等于日蓄热量时,确定温室北墙体适宜长度为89.4~102.5 m;累积日有效积温与北墙体长度呈幂函数关系,北墙体长度越大,其累积日有效积温越低。

The solar greenhouse in Lanzhou was used as the study object, and the model of solar greenhouse was established and verified by the experimental results, to simulate and analyze the effect of the length of greenhouse north wall on the thermal environment under different weather conditions. The shadow rate of the north wall, the daily heat release/storage of the solar greenhouse and cumulative daily effective accumulated temperature were used as evaluating indicators to explore the effect of the length of greenhouse north wall on the indoor thermal environment. The results showed that the shadow of north wall was caused by the east wall and the west wall of solar greenhouse. The shadow rate was symmetrical at 13： 00. When the insulation quilt was opened or closed, the shadow rate of north wall was the largest and with the increase in the length of greenhouse wall, its shadow rate gradually reduced at other times. Under different length of the north wall and retaining the other structural parameters of solar greenhouse, the ratio of daily heat release/storage was nonlinearly related to the solar radiation intensity and the length of north wall. When the daily heat release was equal to the daily heat storage, the suitable length of the north wall of solar greenhouse was from 89.4 m to 102.5 m in Lanzhou. Moreover, the cumulative daily effective accumulated temperature had a power function relationship with the length of north wall, the larger the length of the north wall, and the lower the cumulative daily effective accumulated temperature.