超低能耗居住建筑预制混凝土夹心保温墙体桁架式连接件热桥效应研究

Study on Thermal Bridge Effect of Precast Concrete Sandwich Insulation Wall Truss-type Connectors for Ultra-Low Energy Residential Buildings

围护结构的热工性能是建筑节能的重点,针对高热工性能围护结构的应用需求,本文以预制混凝土夹心保温外墙为例,依据严寒、寒冷地区近零能耗建筑的热工指标限值,通过模拟墙体的三维稳态传热过程探究了当墙体使用超厚保温时桁架式连接件异型构造处的热桥问题。总结了桁架式连接件热桥效应的关键控制要素,并以外墙三维稳态传热为视角揭示了墙体热桥影响区域的一般规律,提出了局部传热的表征体元选取方法。结果表明:当外墙保温层厚度为180~340 mm时,由钢筋、不锈钢、玻璃纤维增强复合塑料桁架式连接件造成的外墙平均传热系数增长率分别为13.25%~22.55%、4.02%~6.62%、0.17%~0.29%;桁架式连接件热桥效应的关键控制要素为连接件导热系数,其次是连接件直径、保温层导热系数与连接件间距,最后是保温层厚度、锚固长度与外饰面厚度。

The thermal performance of building envelopes is the focus of building energy conservation. In view of the application requirements of high thermal performance building envelopes, this paper took precast concrete sandwich insulation external walls as an example, and explored the thermal bridges at the special-shaped structure of truss-type connectors when ultra-thick insulation is used in walls by simulating the three-dimensional steady-state heat transfer process of walls according to the thermal index limits of nearly-zero energy buildings in cold and severely cold areas. The key control factors of the thermal bridge effect of truss-type connectors were summarized, and the general rule of the influence area of thermal bridges in walls was revealed from the perspective of three-dimensional steady-state heat transfer of external walls. The results showed that when the thickness of the external wall insulation layer was 180 ~ 340 mm, the average heat transfer coefficient of external walls increased by 13.25% ~ 22.55%, 4.02% ~ 6.62% and 0.17% ~ 0.29%, respectively, under the effect of steel bars, stainless steel and Glass-Fiber Reinforced Plastic(GFRP) truss connectors;the key control factor of the thermal bridge effect of the truss connector was the thermal conductivity of the connector, followed by the diameter of the connector, the thermal conductivity of the thermal insulation layer and the distance between connectors, and finally the thickness of the thermal insulation layer, the anchoring length and the thickness of the exterior facing.