The Research On Coupled Heat And Moisture Transfer Characteristics Of Bamboo Structure Wall

Energy is an important material basis for human society to survival and development, and the development and efficient use of energy has been a constant pursuit of the goal of human society. Building energy consumption as the important component in energy consumption, has been the main direction of a national energy conservation. Building envelope thermal performance of play a fundamental role in building energy consumption. in the summer, the heat coming from outdoor can be reduced; in the winter, heat loss to the outdoor can be reduced, so that thermal environment can be improved, thereby reducing the building consumption. Therefore, started with the component parts of building envelope’s thermal performance has a very real sense.In this paper play a detailed analysis and discussion on the coupled heat and moisture characteristics of the wall of bamboo structure. First, through theeanalysis of the moisture migration process inter the bamboo in the summer and winter,can be drawn: the diffusion of water vapor in bamboo and air infiltration has a close relationship with their material properties and the air pressure inside and outside surface; air permeability change the water vapor pressure gradient inside the bamboo, so that the amount of water vapor migration by diffusion has a greater change. When the air flow from the outdoors into the room, water vapor pressure gradient increases, thus increasing the diffusion flux, the maximum point of the relative humidity shifted to the interior; when the air leak from the interior to the outside, the water vapor pressure gradient decreases, the flow of water vapor mass diffusion reduced, the maximum point of the relative humidity shifted to the outside.Secondly, puting the capillary pressure and the air temperature in the the pore of bamboo structure wall as the driving potential, establish the migration model equations of the coupled heat and moisture transient within the bamboo structure wall. Using the finite element method for spatial discretization, while implicit finite difference for time discretization, and iterative method to solve the equations. The Changsha meteorological parameters has used to calculate 10 days of coupling heat and moisture.on the bamboo walls.Analysis method used to solve the coupled heat and moisture in the structure of the bamboo.Based on the Luikov equations, established coupled heat and moisture migration model in the bamboo structure wall,using Laplace transformation. First, the transmission equation, boundary and initial conditions for the Laplace transform, transfer function and the first use of coupled heat and moisture transfer equation will be converted to fourth-order ordinary differential equations, and then combined with the boundary conditions and initial conditions of the coefficient matrix Laplace Laplace domain by the temperature and humidity distribution, and then its inverse Laplace transform the physical space of the temperature and humidity distribution.Finally, a experiment research has carried out on the coupled heatand moisture transfer of bamboo structure wall, analysised of the temperature, relative humidity distribution of the bamboo structure wall in the summer and winter, and the relation of temperature, humidity, solar radiation transmission with the coupling heat and moisture transfer in the bamboo structure wall. To the cement mortar - steam pressure concrete block - bamboo wall, the experimental results show that:(1) Whether in summer or winter, there are the the coupling heat and moisture in bamboo structure wall, and analysised the impact of the temperature humidity and solar radiation intensity on the coupling heat and moisture transfer inside wall, significantly there is a big change in the of temperature and humidity distribution of the wall.(2) Whether in summer or winter, the temperature and humidity at the interface of ocement mortar and concrete block steam mainly orded by the outdoor temperature and humidity, the temperature, humidity has the same shape.with the temperature and humidity of outdoor air.(3) Whether in summer or winter, the relative humidity of the interface steam pressure of cement mortar and concrete blocks the may reach saturation point, and for a long time, the interface’s relative humidity above 80%, especially in the winter.