秸秆块墙体日光温室在苏北地区应用效果试验

    Application of sunlight greenhouse with straw bale thermal insulation wall in north of Jiangsu province

    • 摘要: 为探讨秸秆块构建日光温室墙体的可行性,分析了小麦秸秆块对空气水分吸附解析性能及其导热性能,并在苏北地区建造了一座小麦秸秆块墙体日光温室,以土墙体和砖墙体日光温室为对照,监测了3种温室室内外空气温度、空气湿度、土壤温度、土壤湿度及作物产量。结果显示,小麦秸秆具有相对稳定水吸附与解吸性能,高空气湿度下小麦秸秆吸附空气水分,低空气湿度下小麦秸秆所吸附的水发生解吸作用,秸秆含水率与所处空气湿度呈正相关。与砖墙和土墙相比,秸秆块墙热传导率、体积热容和热扩散系数显著低于前两者,这种热工特性利于隔热保温但不利于蓄积热量。田间监测发现,秸秆块墙体温室内平均气温和土温比土墙体温室分别低2.1和1.1℃、比砖墙体温室分别高1.3和1.2℃,但整个冬季秸秆块墙体温室最低气温为9.6℃,最低土温为12.1℃,可以保障所定植彩椒安全越冬;冬季覆膜条件下,秸秆块墙体温室室内空气湿度最低,砖墙和土墙温室空气湿度比秸秆块墙体温室平均高出10个百分点,秸秆块墙体秸秆含水率在12.5%~23.6%区间波动;土墙体、砖墙体和秸秆块墙体日光温室的彩椒产量分别为6 375,7 130和6 833 kg。秸秆块替代土壤、红砖等常规建材构建日光温室保温墙体具有可行性,有利于节约土地资源和实现秸秆综合利用。

       

      Abstract: Abstract: The straw-bale has been widely used in the building field, compared to the traditional architecture material, it has lots of advantages such as high thermal resistance value, light weight, and environmental friendly material. In order to investigate the application effect, a solar greenhouse was designed and built with straw-bale. The performance of straw-bale wall solar greenhouse was evaluated, and compared with the soil wall and brick wall solar greenhouse. The hygroscopicity and desorption of straw, and thermal conductivity of straw-bale were evaluated. The moisture content of straw-bale, temperature and humidity, crop yield, morbidity of different solar greenhouse (soil wall, brick wall, and straw-bale wall) were discussed in the paper. The results showed that the maximum moisture content of straw was about 22.0% under the condition of 97% relative humidity and 25℃ temperature, while the maximum moisture content of straw in the solar greenhouse was 23.6% during the experiment. The thermal conductivity of straw-bale with density of 0.20 g/cm3 was 0.069 W/(m·K), while the thermal conductivity of soil wall and brick wall were 1.210 W/(m·K) and 0.982 W/(m·K). The inertia index of straw-bale wall (0.46 m), soil wall (4.0 m) and brick wall (0.5 m) were 5.603, 43.513, and 4.636, respectively. The air temperature in the straw-bale wall solar greenhouse was 1.3℃ higher than that in the brick wall solar greenhouse, and 2.1℃ lower than that in the soil wall solar greenhouse. All the air temperature of solar greenhouse was above 9.0℃ when the outdoor temperature was -7℃. The soil temperature in the straw-bale wall solar greenhouse was 1.2℃ higher than that in the brick wall solar greenhouse, and 1.1℃ lower than that in the soil wall solar greenhouse. All the soil temperature of solar greenhouse was above 12.1℃ when the outdoor temperature was -7℃. The average air relative humidity of straw-bale wall, soil wall, and brick wall solar greenhouse were 75%, 87%, and 84%, respectively. The straw-bale displayed the adjusting capacity at some extent for the greenhouse air humidity due to the structural porosity of straw. It can not only improve the internal environment of greenhouse, but also restrain the occurrence of plant diseases. During full fruit period of the planted color peppers, the morbidity in the greenhouse with soil wall, brick wall, and straw-bale wall were 25%, 50% and 0, respectively, and the crop yields in the three kinds of greenhouse were 6 375, 7 130 and 6 833 kg, respectively. What's more, according to the design in the work, 35 000 kg straw (air dried) had been used to build the straw-bale wall solar greenhouse in this study. Also, the utilization rate of the land can improve by 34.6% due to reducing the wall thickness. In a conclusion, the straw bale has the potential to replace the soil or brick wall for building solar greenhouse thermal insulation wall. Further research should be paid attention on optimization of the straw greenhouse structural design, for example, the wall base and outer surface structural improvement, so as to elevate the thermal performance of straw bale greenhouse.

       

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