Basic Research On Mold Growth Of The Building Inner Wall Surface Based On Thermal-moisture Coupling Effect

The mould growing on the wall surface can affect the health of human body,damage the outlook of the interior walls and furniture,and furturely result in the loss of residents' property and reduce the life expectancy of the wall structure.In order to alleviate the harm caused by mould,this paper studied the growth of mould on the wall.The main contents of this paper include:the optimized selection of mould prediction model and heat moisture coupled transfer model,the survey of mould growth,the sensitivity of mould to different factors,the related experiment of mould growth on the wall,the regional analysis of mould growth on the wall in different regions and the optimized selection of wall structure in Shenyang area.In this paper,the factors that influence the growth of mould and the basic characteristics of mould growth were firstly studied by reading a lot of domestic and foreign literatures.Then,different heat and moisture transfer models of wall and mould growth predictive models were studied.After the furture analysis of the advantages and disadvantages of different model,The CHAMPS utilized unstable heat and moisture coupling transfer model of wall and the WUFI-Bio-utilized Biohygrothermal model are optimized.The combining of these two models can predict the mould growth of the wall surface more accurately.The main factors affecting the growth of mould are temperature,humidity,and the mould growth substrate containing nutrients,and mould growth time.The sensitivity analysis method was used to determine the sensitivity coefficient of mould growth rate to different factors,the greater the sensitivity coefficient,the greater the effect on the growth rate.The growth rate of mould is most sensitive to humidity,and the sensitivity coefficient is between 60?100.The higher the humidity is,the easier for the mould to grow,and the maximum sensitivity coefficient appears between the humidity range of 85%?90%,where the mould growth rate increases most rapidly.To prevent the rapid growth of mould,the wall surface humidity should be controlled below 85%.The minor factor that affected the growth of mould is the mould growth substrate,and the sensitivity coefficient is 20?70.Therefore,controling mould growth should also try to reduce the nutrients on the surface of the wall.However,the growth rate is least sensitive to temperature,and the sensitivity coefficient is between 0?30,which shows that the temperature has the minimum effect on the growth rate.The questionnaire was used to investigate the indoor mildew condition,which contained the characteristics of mould growth in different regions of China,the characteristics of mould growth and the impact of the house using condition on the mould growth.The analyzed results show that the indoor ventilation,the choice of decoration materials,the use of the wall insulation board,and the use of the kitchen would have impact on the production of mould.In order to accurately predict the mildew condition of the wall in Shenyang area,the mould was collected from different buildings,then cultured,observed and microscopic examinated.It was found that the mould species in Shenyang area was mainly penicillium and yeast.When the humidity is 99%,the minimum time of the penicillium mildewed in the building material of the rich nutrition is 14 days.The minimum mildewing time is 17 days when the humidity turns to 90%.CHAMPS and WUFI-Bio were utilized to simulate the mildew condition in different regions of China with different wall structures and the wall substrate.From the simulation results we can see that the use of sintered clay brick makes the wall easier to mildew.Besides,the temperature and humidity of the south region is higher,resulting in the more serious mildew condition of the wall in south area.The Wall mildew severity ranking is Guangzhou,Shanghai,Kunming,and Beijing.While the least serious mildew condition appears in Harbin region.Taking Shenyang area as an example,this paper choosed the optimal wall structure by analytic hierarchy process considering three factors,which are the wall of the wall,the heat load of building and the building envelope.According to the experimental results and the existing mould prediction model,the prediction model which is more suitable to Shenyang area was formulated,this model can better predict the indoor mould growth in Shenyang area.Through calculation,the wall structure that most suitable to the Shenyang area is the 240mm concrete adding 80mm heat insulation board.This paper presents an effective method to prevent the mold growth,and provides a basis theoretical to prevent mold growth.