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Moisture adsorption in glass wool products
Laurent Marmoreta, Florence Collet and Hassen Beji
Two glass wool insulating materials are studied. After describing the microscopic and macroscopic structure of the wool, the investigations are concentrated on water vapour sorption isotherm. The aim of this study is to calculate the values of parameters obtained by the regression of water sorption experimental data using Brunauer, Emmett and Teller (BET) and Guggenheim, Anderson and de Boer (GAB) and Three Sorption Stages (TSS) isotherms. We have chosen these isotherms because of their complementarity’s range of relative pressures regression. BET isotherm can be applied for data until 0.4 even though GAB isotherm can be fitted until 0.84 and TSS one can be used on the whole range of relative pressures. Usually, new parameters are calculated independently for each (BET, GAB or TSS) model. There after, these values obtained from different models are compared. We have used this method in a first time. In a second time, another method is proposed: parameters are not independently calculated but values of the two parameters (monolayer and the energy constants) determined with the BET model are retained and used in the GAB model. So, we fit the experimental data with the BET values and a new additional constant, denoted k. Thereafter, GAB parameters are completed in TSS model by introducing a new constant, called h* to fit the whole range of relative pressures.
Keywords: Insulating material, mineral wool, glass fiber, adsorption isotherm, BET model, GAB model, TSS model