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Investigation of the thermal insulation performance of fibrous aerogel samples under various hygrothermal environment: Laboratory tests completed with calculations and theory
Energy and Buildings ( IF 6.7 ) Pub Date : 2020-02-25 , DOI: 10.1016/j.enbuild.2020.109902
Ákos Lakatos

Insulation materials are mainly porous or fibrous materials. Therefore, the presence of moisture can easily cause problems inside the materials, and in the whole building structure. For correct calculations of heat and moisture transfer problems in building applications, practitioners need design values. Design thermal values are deduced and calculated from declared values which are reached from laboratory measurements. This is the case for both insulation and building materials. If the design environments are different from those where the declared values should be used, the data have to be changed to the relevant conditions. There are standards giving suggestions on how to calculate the design values of thermal insulation materials, however, their database and tables are insufficient regarding the values of the super insulation materials. In this paper, a calculation method will be presented so as to specify the design thermal conductivities of a glass fiber-reinforced aerogel. The calculation method is based on measurement results, where the lambda values were measured treating the samples in a humid environment. As a result, the moisture conversion coefficient for the thermal conductivities is obtained after measuring the humid thermal conductivities of materials. Moreover, a new calculation method will also be presented to estimate the vapor absorption coefficient from humidity measurements. Furthermore, the effects of ice and freeze on the thermal conductivities of the aerogel samples are characterized, too. The thermal conductivities were measured in a Holometrix type heat flow meter, while for the wetting a Venticell 111 type drying apparatus and a Climacell 11 climatic chamber were applied. Moreover, the cooling treatment was executed in a freezing room. In addition, new theory for the thermal conductivity was given, for moist/frost insulation materials.



中文翻译:

各种湿热环境下纤维状气凝胶样品的隔热性能研究:通过计算和理论完成的实验室测试

绝缘材料主要是多孔或纤维材料。因此,湿气的存在很容易在材料内部以及整个建筑结构中引起问题。为了正确计算建筑应用中的湿热传递问题,从业人员需要设计值。根据实验室测量得出的声明值推导出设计热值并进行计算。保温材料和建筑材料都属于这种情况。如果设计环境与应使用声明值的环境不同,则必须将数据更改为相关条件。有一些标准建议如何计算隔热材料的设计值,但是,关于超级隔热材料的值,它们的数据库和表格并不足够。在本文中,将提出一种计算方法,以指定玻璃纤维增​​强气凝胶的设计热导率。计算方法基于测量结果,在此测量的是在潮湿环境中处理样品时的λ值。结果,在测量材料的湿热导率之后,获得了热导率的水分转化系数。此外,还将提出一种新的计算方法,以根据湿度测量值估算蒸气吸收系数。此外,还表征了冰和冻结对气凝胶样品的热导率的影响。热导率是在Holometrix型热流量计中测量的,为了润湿,使用了Venticell 111型干燥设备和Climacell 11气候室。另外,在冷冻室中进行冷却处理。另外,给出了用于湿/霜隔离材料的热导率的新理论。

更新日期:2020-02-25
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