Effect Of Solar Energy Heating Phase Change Energy Storage Wall On Indoor Thermal Environment

The development of ecological livable energy-saving houses is an important part of the construction of new socialist houses.my country has very rich solar energy resources.Taking advantage of regional solar energy resources to develop passive solar buildings is an important measure to promote energy conservation in rural buildings.However,solar energy has the characteristics of intermittent and instability,which can easily cause excessive fluctuations in the indoor thermal environment.Different from general sensible materials,phase change energy storage materials have the advantages of high heat storage density,isothermal storage and heat release process,etc.The development of phase change energy storage walls has a positive effect on alleviating the mismatch between supply and demand of solar thermal energy in time and space.In this paper,the phase change energy storage wall is applied to the design of passive solar heating buildings in order to solve the contradiction between indoor thermal comfort improvement and energy saving and emission reduction.Through field test on the existing rural buildings in Lhasa area,the structural characteristics and corresponding thermal parameters of the rural building envelope structure and the indoor thermal environment conditions of the local rural houses were mastered.Aiming at the shortcomings of low indoor air temperature and large temperature amplitude,the idea of combining phase change energy storage walls with solar heating buildings is proposed to improve the indoor thermal environment quality.In this study,the heat transfer equation of the phase change energy storage wall was derived based on the sensible heat capacity method.Using the CDMSOL software as a platform,the heat transfer model of the phase change energy storage wall was established to analyze the thermal characteristics of the phase change energy storage wall.Combined with the main factors affecting the heat transfer performance of the phase change energy storage wall,a phase change energy storage wall type solar heating building model was established to explore the influence of the phase change temperature,phase change latent heat value and other factors on the indoor thermal environment.The research results are as follows:(1)Based on the COMSOL software,the geometric model and the meshing model of the wall under the four construction modes are constructed,and the heat transfer process of the wall is simulated and calculated.The appropriate wall structure is selected with the indoor air temperature as the evaluation index,and the phase is found.When the variable material layer is arranged inside the wall,the indoor thermal environment has the best temperature adjustment effect.(2)In order to explore the heat storage capacity of the phase change energy storage wall,the phase change temperature and the thickness of the phase change material layer are used as two-factor variables,and the internal surface temperature amplitude ratio,internal surface temperature peak time difference,and heat storage are used as the evaluation criteria to determine Heat transfer characteristics of phase change energy storage wall.The surface temperature and heat flux density of the phase change energy storage wall and the ordinary wall body are compared,and the effects of the phase change temperature and the thickness of the phase change material layer on the thermal characteristics of the phase change energy storage wall under static/dynamic boundary conditions are analyzed.Phase change materials can reduce the temperature fluctuation of the inner wall surface,delay the appearance of temperature peaks and improve the heat storage capacity of the wall.(3)Taking Lhasa and Yinchuan as examples,this study analyzes the suitability of thermal parameters and thickness of solar energy building phase-change energy storage walls.The suitable phase transition temperature in Lhasa is 13?15?,and the suitable phase transition temperature in Yinchuan is 12?14?.The latent heat value of phase change materials is one of the important influences on the heat storage capacity of phase change composite walls.Compared with the Yinchuan area,when the latent heat value of the phase change wall is increased by the equivalent value,the heat storage of the wall formed by the solar building in Lhasa area increases more.This shows that the heat storage generated by the increase of the phase change latent heat value in areas with high solar radiation intensity is more significant.In Lhasa,the appropriate thickness of the phase change material layer is 30mm;in Yinchuan,the appropriate thickness of the phase change material layer is 20mm.(4)For buildings that use phase-change energy storage walls,different layout schemes have different effects on the indoor thermal environment.When using phase change materials in three walls,the phase change materials used in west,south,and north have the best effect on indoor temperature adjustment,which is similar to the effect of all phase change materials on four walls.When phase change materials are used in two walls and one wall,the phase change materials play a certain role in regulating the indoor thermal environment,but they still cannot meet the indoor thermal comfort requirements.(5)In the Lhasa area,the uncomfortable hours during the heating period before optimization were 1962?·h,and the uncomfortable hours during the optimized heating period were 1065?·h,compared with the uncomfortable hours during the heating period after optimization Reduced by 45.7%,excessive comfort hours and cold and uncomfortable hours decreased by 22.8%and 44.9%,respectively.In Yinchuan area,the uncomfortable hours during the heating period before optimization were 2038?·h,and the uncomfortable hours during the optimized heating period were 1307?·h,compared with the uncomfortable times during the heating period after optimization The number decreased by 35.9%,and the hours of cold and uncomfortableness and hours of excessive comfort decreased by 37.3%and 14.6%,respectively It can be seen that under the conditions of natural operation in winter,the minimum value of the indoor temperature can be significantly improved through optimization,and the thermal environment is significantly improved,while reducing energy consumption.Through the research in this paper,we hope to provide useful theoretical reference for the application of phase change materials in solar energy buildings.