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外保温结构中保温材料的有效热阻随温度、湿度和使用年限的增加而下降,造成墙体传热系数大于设计值。为此,本文以耦合传热传湿模型为基础,结合保温材料的有效导热系数模型,以分别采用发泡聚苯乙烯,挤塑聚苯乙烯和聚氨酯泡沫作为保温材料的外墙保温结构为例,数值预测了长期实际气候下外墙保温结构的传热系数。计算结果表明,采用上述三种保温材料的墙体传热系数在20年后因保温材料热阻蜕变有不同程度的增加,这意味着需要增加保温层设计厚度才能保证墙体热损失达到设计值。
The effective thermal resistance of insulation materials in external insulation structure decreases with the increase of temperature, humidity and service life, resulting in wall heat transfer coefficient greater than the design value. Therefore, based on the coupled heat and moisture transfer model and the effective thermal conductivity model of insulation material, the exterior insulation structure with polystyrene foam, polystyrene foam and polyurethane foam as insulation materials is taken as an example , Numerically predicted the heat transfer coefficient of the external wall thermal insulation structure under long-term actual climate. The calculation results show that the heat transfer coefficient of the wall with the above three kinds of insulation materials increases with different degrees due to the thermal resistance of the insulation material after 20 years, which means that the thickness of the insulation layer needs to be increased to ensure that the wall heat loss reaches the designed value .