Balconies significantly affect the thermal performance of building envelopes. They are mostly constructed with porous materials, so the coupled heat and moisture transfer under hot-humid climatic conditions requires in-depth research. This study adopts numerical simulation method to investigate the heat and moisture transfer characteristics of a novel thermal break cantilever balcony in hot-humid climate regions, with ordinary cantilever balconies as the control group. The results show that: 1) When only heat transfer is considered, the thermal bridge influence range of the novel thermal break cantilever balcony is 69.9% lower than that of the ordinary balcony and 18.4% lower than that of the conventional thermal break balcony. When considering coupled heat and moisture transfer, the thermal bridge influence range of the novel thermal break cantilever balcony decreases by 89.1% and 45.1% respectively. 2) The novel thermal break cantilever balcony achieves faster moisture discharge. The three-year average moisture content of the novel structure, conventional thermal break balcony and ordinary balcony decreases by 7.0%, 5.1% and 4.7% respectively. This study can provide references for the optimization of building envelopes in hot-humid climate regions.
许多学者从热湿耦合传递角度开展了建筑围护结构性能研究[9-14]。王莹莹等[15]以相对湿度和温度为驱动势,建立墙体热湿耦合传递模型,研究湿传递对墙体传热的影响,结果表明,在考虑湿传递时墙体内表面相变潜热约占总传热量的27.5%,与不考虑湿传递的墙体内表面温度相差0.9 ℃。李会敏等[16]通过研究寒冷地区钢筋混凝土柱与红砖墙形成的热桥,发现考虑湿传递作用时墙体内表面的温度会比只考虑传热作用时低,热桥使围护结构热通量增加19.6%,热桥的影响区域为距离最不利点0.4 m 左右。阳台板与外墙的连接部位是湿气积聚的高频区域,也是潜在霉菌生长的敏感部位。准确分析热桥的影响范围,可为进一步的针对性优化提供参考。
阳台热桥区域内表面温度随室外气温呈现出稳定的年周期变化规律。基于此规律,本研究将聚焦于一个典型年份展开分析。对比仅考虑热传递与热湿耦合传递两种模拟情况发现,在热湿耦合条件下,测点的内表面温度在考虑热湿传递时低于单纯热传递工况。这主要是由于湿分相变过程中吸收了一部分热量,从而降低了内表面温度。受初始含湿量影响,在模拟初期,A 点与 C 点之间的温差变化不大;然而,模拟时长超过六个月后,热湿耦合作用使两点间的温差进一步增大。该现象表明,相较于主体墙体区域,热桥区域的内表面温度对湿传递过程更为敏感。
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