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New method to quantify liquid transport inside hydrophilic interior insulation materials

: Binder, A.; Zirkelbach, D.; Künzel, H.M.

Zmeskal, O. ; Brno University of Technology (Veranst., Hrsg.):
Thermophysics 2010. Proceedings : 3rd to 5th November 2010, Valtice, Czech Republic, Brno University of Technology
Brno: Brno University of Technology, 2010
ISBN: 978-80-214-4166-8
Conference "Thermophysics" <12, 2010, Valtice>
Conference Paper
Fraunhofer IBP ()

Interior insulation systems influence the hygrothermal behaviour of a construction. Therefore, special attention is required towards its hygrothermal design. One approach, that is recently becoming increasingly popular, is based on the concept of capillary activity. By using vapour permeable hydrophilic insulation materials, liquid moisture occurring inside the construction can be transported back towards the interior surface to a certain extent, which helps to control the moisture level inside the construction beneath critical values. To determine a building component's hygrothermal performance prior to construction, detailed material properties have to be at hand. For various reasons, the common test methods to quantify liquid transport often do not deliver adequate results for the specific purpose. Therefore, a new laboratory test has been developed, that is carried out under conditions similar to real life. Under defined boundary conditions, a temperature below the dew point is applied to a laterally sealed material sample, thus generating a gradient of partial pressure. The insetting vapour diffusion into the material leads to a rising moisture content and increased relative humidity at the cold side of the material. A liquid transport reverse to vapour diffusion sets in. By performing regular gravimetric as well as nuclear magnetic resonance measurements, both water gain and distribution across the sample are monitored, serving as a basis to fine?tune the liquid transport coefficients via hygrothermal computational simulation. On the basis of a fibrous insulation material, the results of the new measuring method are demonstrated and compared to the results of conventional test methods.