| Abstrakt: |
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°C 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°C higher than that in the brick wall solar greenhouse, and 2.1°C lower than that in the soil wall solar greenhouse. All the air temperature of solar greenhouse was above 9.0°C when the outdoor temperature was -7°C. The soil temperature in the straw-bale wall solar greenhouse was 1.2°C higher than that in the brick wall solar greenhouse, and 1.1°C lower than that in the soil wall solar greenhouse. All the soil temperature of solar greenhouse was above 12.1°C when the outdoor temperature was -7°C. 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. [ABSTRACT FROM AUTHOR] |
