Validation And Application Of Simulation Calculation Model For Dynamic Coupled Heat And Moisture Transfer In Building Envelopes

Accurate dynamic models for the coupled heat and moisture transfer are important to simulate and predict the hygrothermal performance and to improve the indoor environment and structure durability.The dynamic hygrothermal models need to be fully validated.However,literature review revealed that these models have not been fully validated.Therefore,this study summarize the validation method of the coupled heat and moisture transfer model and summarize it into a set of widely used comprehensive validation methods to validate the dynamic coupled heat and moisture transfer model.A comparison and comprehensive verification,i.e.,including theoretical verification,inter-model verification and experimental verification,was performed on two models,the Künzel model and the Liu model for the hygrothermal simulation of porous building envelopes,which are driven by relative humidity.The simulations were also carried out by two computation tools,self-programmed Fortran code and COMSOL Multiphysics for the two models.The verification showed that the simulation results of the two models agree well with the comparison values.Comparing the simulation results of the two models,it was found that the two models have little difference in the low relative humidity section in the hygroscopic range;while in the end of the hygroscopic range(relative humidity gradually increases to nearly 95%),the Künzel model can no longer accurately simulate the distributions of moisture.The investigations in this study demonstrate that the two models are fully validated within the hygroscopic range and provide references for the verification of future hygrothermal models.Based on the comprehensive validation of the model,this study used the Liu model to simulate the application of the following two aspects:The Liu model is initially used in the application of hygrothermal simulation studies,and the simulation results are compared with the measured results of experimental data sets in the existing literature.This study compared the difference between the simulation results and the measured values;then,simulated the indoor environmental response under fluctuating heat and humid conditions;and finally,separately conducted the hygrothermal simulation of two general buildings and Roggerdorf church under the future climate conditions.This application is of general significance for predicting the moisture distribution and migration in the building envelope components.Internal insulation of historic building walls may cause hygrothermal damages such as mould growth,wood decay,etc.It is important to accurately predict the growth of mould and the decay of wood components for assessing the risk of heat and moisture damage in buildings.This study used a well-verified dynamic coupled heat and moisture transfer model to establish a two-dimensional model in COMSOL software and perform hygrothermal simulation to complete the experimental verification of the model by using the experimental case in the literature.On the base of that,the existing mould growth model and wood decay model were used to evaluate the mould growth risk of historical building walls and the wood decay risk of internal wooden components by using the results of hygrothermal simulation,Respectively.This research has positive significance for the renovation and protection of historic buildings.