A method to analyze the transient hygrothermal behaviour of building materials and components: Dissertation

A method has been introduced for the analysis of the hygrothermal behaviour of building materials and construction.The model equations for coupled heat and mass transfer used in the computer code TRATMO and in the determination of hygrothermal transport properties of materials are derived using the local volume averaging technique.In the energy balance equation the conduction, convection and accumulation of heat are considered as well as the generation of heat due to interstitial phase changes.The corresponding accumulation of moisture, diffusion in gas phase, surface diffusion and viscous flow of water vapour are considered in the moisture balance equation together with capillary and viscous flows of liquid water.Also introduced are methods for determining the diffusion coefficient of water vapour, moisture diffusivity and permeability as well as thermal conductivity and capacity.The numerical algorithm for the system of IWO coupled diffusion convection type equations used in the computer code TRATMO has been formulated using non-equidistance space differentiation and the trapetzoidal rule for the time derivative.The accuracy of the numerical algorithm is verified with an analytical solution of the model equations.In addition, a number of laboratory and field tests have been carried out in order to verify the validity of TRATMO.