Research On The Long-Term Performance Of Stone Wool ETICS Under Coupled Heat And Mass Transfer Impact

With the increasing requirement for the fire performance of ETICS in China,stone wool ETICS is used more and more as a Class A fire performance system.Most of the previous researches are focused on material properties.Few researches are based on quantitative analysis of stone wool ETICS.Therefore,these studies are unable to establish the relationship between long-term performance of and hygrothermal distribution of stone wool ETICS.In view of the application and development of stone wool ETICS,it was summarized into three basic structural forms.Based on the characteristics and requirements of coupled heat and mass transfer,three basic structural forms of stone wool ETICS are condensed into one simplified structural model suitable for coupled heat and mass transfer.The simplified construction model provides a practical basis for the hygrothermal analysis and establishes a reliable relationship between theoretical analysis and engineering application.This research takes the typical stone wool ETICS construction in China as test research object.Comprehensive tests of concrete and stone wool,EPS,adhesives,render coating were done in this research for the first time,which including the basic physical properties,thermal physical properties and mositure physical propertie.Especially,the water absorption coefficient,liquid water diffusion coefficient and specific heat tests for the adhesive and render coating fill the gaps in the domestic related research.In the test and analysis of thermal conductivity,the error of the test system is studied,the method of correcting contact thermal resistance is proposed,and the coupling effects of temperature and moisture on thermal conductivity of building materials can be simplified to the 2-variable linear function.This research choose stone wool ETICS as a whole object and establish coupled heat with moisture transport equation.According to the characteristics of the stone wool ETICS and porous media,simplified assumptions was set for coupled heat with moisture transport physical model.Based on the continuity principle of heat and moisture transfer,the balance equation of stone wool ETICS is given for the first time,which take the temperature and relative humidity as driving potential.This method is simple in form and easy to understand and calculate.Simulations of stone wool ETICS were done under different conditions to analyze the moisture content in each layer of the system.An important issue to be solved currently is how to propose reasonable indicators for water vapour and liquid water transfer performance in stone wool ETICS in different climate zones in China.Simulations of different render coating performances were also done to analyze the moisture content in each layer.―unsteady-state liquid water – water vapour model‖ is more close to the actual situation.The effects of rainfall of stone wool ETICS are far greater than the influence of air relative humidity.The moisture content of thermal insulation layer in ETICS is also affected by the water vapour diffusion resistance of wall.Based on these,indicators for water vapour and liquid water were proposed,which provides a foundation for the stone wool ETICS standards in China.Finally,the definition and connotation of the "Long-Term Performance(LTP)" of the stone wool ETICS under the hygrothermal action is proposed in this study.This method simplifies the Long-Term effect to a periodic cycle which include two-way HAM transfer.The method for determining the peak value of temperature and humidity load is given by taking into account the influence of frequency domain on the basis of periodic cycle.The change rule of LTP of the stone wool ETICS is analyzed.This paper puts forward the evaluation factor of thermal performance cumulative effect(),the evaluation factor of the safety performance cumulative effect()and the evaluation factor of the durability cumulative effect().These factors can be used to quantify the degree of changes in the overall performance of stone wool ETICS as time changes.The comprehensive evaluation index for the long-term performance(WLp)of stone wool ETICS under the hygrothermal action is proposed and its calculation method is made clear.