Experimental Study On Coupled Heat,Air And Moisture Transfer Characteristics Of Composite Block Walls

With the increasing demand for building energy efficiency,new wall materials,such as composite thermal insulation block,are widely used in building walls.The structure of composite block wall composed of main material and filling material is non-uniform,and the coupling of heat and moisture transfer of wall is approximately one dimension,and the process of transmission will lead to great deviation.The air pressure of the building wall is affected by the outdoor air pressure,and the air infiltration under the pressure difference will affect the heat and moisture transfer characteristics inside the wall.The filling material of composite block is mostly material with good thermal insulation property,its air permeability is stronger,and filling material is mostly located in the middle of block.If the material is damp,it will reduce the thermal performance of the wall.If the consequences of the wet transmission in the wall are not fully considered,it will lead to wall surface erosion,leakage,mildew and even damage to the structure during the construction process.In order to ensure the normal use of the wall,it is necessary to study the coupled characteristics of heat,moisture and air transfer in the composite block wall.1)Fly ash concrete composite block by using the self-developed production test wall side of 1500mm×290mm×2400mm(Width×Thickness×Height).Based on considering the temperature and humidity and the wind pressure on the pass distribution of fly ash concrete composite insulation block,to determine the temperature and humidity measuring point position,set up for the test pressure of composite block wall under the action of heat and moisture and air permeability coupling transfer characteristic test device.2)In the artificial climate environment and indoor air environment under the condition of fly ash composite insulation block wall in the two-dimensional heat and moisture transfer properties of the coupling was studied by experiments results show that the fly ash composite insulation block wall thickness and width of cross section are section of heat and moisture transfer,as the main direction of the wall thickness the direction of transmission but there are some differences in temperature and humidity in the width direction,so this is a two-dimensional coupled heat and moisture transfer process will be simplified to one-dimensional deviation.3)The test on the wall pressure on both sides of fly ash concrete composite insulation block wall temperature and relative humidity inside the 0Pa,1013 Pa and 2002 Pa under the condition of composite masonry wall heat,moisture and air permeability coupling transmission characteristics.The results show that when the air permeation direction is in the same direction as the water vapor diffusion direction,it will increase the transfer of moisture content and damp the wall;if reverse,it will weaken the transfer of moisture content,and the wall will be dry.The greater the pressure difference between indoor and outdoor,the more prominent the heat and moisture transfer in the wall,and the influence of air infiltration on the relative humidity distribution is more significant than the temperature distribution.