复合相变材料在建筑节能领域的研究进展

相变材料在解决建筑能耗方面具有广阔应用前景。针对使用单一相变材料容易产生泄漏、导热性差、存在污染性、腐蚀性、过冷和相分离的问题,提出将相变材料制备成复合相变材料再添加到建筑材料中。对相变材料进行了细化分类,介绍了相变材料的选用原则;归纳了两大类最常用的复合相变材料的制备方法和热物性质研究方式;梳理了将相变材料应用到建筑节能领域的多种应用方式;总结了复合相变建筑材料的掺入对建筑控温的应用效果。综合分析表明:复合相变建筑材料的掺入对建筑物温度具有明显的调控效果。温度升高时,复合相变材料吸热降低室内温度;温度降低时,复合相变材料放热提高室内温度。复合相变材料结合建筑材料使用可以在一定程度上提高建筑物的热惰性和热舒适性,但应对其应用耐久性和稳定性应进行进一步研究,最后对其发展趋势进行了展望。

Corner strength enhancement of high strength cold-formed steel at normal room and elevated temperatures

In this study, the suitability of current design methods for the 0.2% proof yield strength of the comer regions for high strength cold-formed steel at normal room temperature was investigated. The current standard predictions are generally accurate for outer comer specimen but conservative for inner comer specimen. Based on the experimental results, an analytical model to predict the comer strength of high strength cold-formed steel at normal room temperature was also proposed. The comparison indicated that the proposed model predicted well the comer strength of high strength cold-formed steel not only at normal room temperature but also at elevated temperatures. It is shown that the predictions obtained from the proposed model agree well with the test results. Generally the comer strength enhancement of high strength cold-formed steel decreases when the temperature increases.