Study On Thermal-moisture Coupling Characteristics Of Assembled ALC Wall

In order to further deepen the construction of ecological civilization,prefabricated buildings have received more and more attention at the national level.Autoclaved aerated concrete(ALC)is widely used in prefabricated buildings to study the heat and mass transfer characteristics of prefabricated ALC for envelope structures,evaluate its thermal and moisture properties,heat and moisture storage capacity,and establish envelope structures.The coupled heat and moisture migration model,predicting the risk of mold growth on the wall,and improving the indoor thermal and humid environment are of great significance.Based on literature analysis,the theory of heat transfer and moisture migration of ALC wall was analyzed with temperature and relative moisture as conduction potential,the interaction between moisture migration and heat migration is considered to establish the ALC one-dimensional transient thermal and moisture coupled transient equation.Case verification and experimental verification of the thermal and moisture coupling mathematical model are carried out,The verification results show the reliability of the new mathematical model.The physical parameters of ALC have an important influence on heat and moisture transfer.The basic physical parameters of B05 ALC are analyzed experimentally.The appearance of B05-grade ALC was characterized by scanning electron microscopy.There are a large number of spherical bubbles and pores inside the ALC,and the diameter distribution of spherical bubbles and pores is determined.The existence of spherical bubbles and pores affects the heat and moisture transfer.The isothermal moisture sorption isotherm of B05 ALC was determined,and the mathematical relationship between the environmental relative moisture and the ALC equilibrium moisture content was established.The thermal conductivity of ALC block with different equilibrium moisture content in B05 grade ALC was studied experimentally.The relationship between thermal conductivity and moisture content was linear and monotonically increasing.Taking the actual meteorological conditions in Shanghai as an example,the verified mathematical model is used to calculate the thermal and moisture coupling process of the ALC wall in the hot summer and cold winter area.The comparison and analysis of the heat and humidity parameters of the inner and outer heat preservation forms of the north-south wall are compared,and the heat and moisture coupling transfer process is compared with the pure heat conduction process,which further shows that moisture migration affects the thermal properties of the wall under actual weather conditions.Impact.On this basis,a wall mold growth risk prediction model is established,and the influence of the north-south wall orientation and different insulation forms on the wall mold growth risk is calculated and analyzed,which provides a reference for the actual project.