Application Of Phase Change Wall And Ventilation Technology In Building Energy Conservation In Hefei

Building energy consumption is an important factor in generating carbon emissions.To achieve the goal of emission peaking and carbon neutralization,we must first overcome difficulties from the construction field.With the enhancement of living conditions,the comfort demanded of office space are also gradually raised.At present,phase change energy storage technology and night ventilation technology have become the research hotspots in Buildings.The two energy-saving technologies can improve the building energy use and room thermal system at the meanwhile to a certain extent.So as to study the efficiency of phase change technology and night ventilation technology in office buildings in Hefei area,this article adopts numerical analysis method to explore the influence of phase transformation temperatures,phase change thickness and phase change arrangement pattern on heat transfer of phase change material wall and the influence level of various factors on temperature attenuation and delay time of phase change wall,and select the optimal phase change composite wall.The effects of different structural phase change material walls on construction energy saving and environmental benefits are analyzed.All at once,the application effects of night ventilation technology,phase change heat storage technology and phase change ventilation coupling technology on indoor comfort and building energy consumption of office buildings in Hefei in different seasons were analyzed.The main work of this paper is as follows:（1）Using Fluent numerical simulation software,one-dimensional unsteady model of phase change material wall has been development.Taking the temperature distribution,attenuation ratio and delay time of phase change wall as evaluation indexes,the temperature influence and major effect factors of phase change material wall heat transfer under different phase change temperature,different phase change layer thickness and different phase change layer arrangement form are discussed.It was found that the effect was the best when the phase transition temperature was 30°C.When the thickness of phase change layer is 30mm,the temperature attenuation factor is 0.2778 and the delay time is 430min.The arrangement of the outer phase change wall can effectively improve the thermal insulation performance in summer,with the temperature attenuation multiple of 0.2926 and the delay time of 400 min.The degree of influence on attenuation coefficient and delay time is:phase change layer thickness>phase change temperature>phase change layer arrangement.Through the comparative analysis of 16 groups of schemes,the best combination of phase change wall is phase change temperature 30°C,phase change thickness 30 mm,and phase change layer is arranged outside.（2）The room energy consumption and environmental benefits of office buildings with different wall structures are compared and calculated.It is concluded that the energy saving and emission reduction effect is the most obvious when the phase transition temperature is 28°C.At this time,the cooling load of the building is 18335.91 k W·h,the electricity cost is 5370.99 yuan,and the carbon emission during the use stage is 53.14kg CO₂/m~2;the effect of energy saving and emission reduction of phase change layer thickness and phase change layer layout is consistent with the effect of phase change wall heat transfer.The optimum thickness of phase change layer is 30 mm.The arrangement of phase change layer outside is more conducive to reducing building energy consumption and carbon emission.（3）Taking an office building in Hefei as the research object,the cooling effect of phase change heat storage technology,ventilation technology and phase change heat storage ventilation coupling technology was studied,and the influence of phase change heat storage technology,ventilation technology and phase change heat storage ventilation coupling technology on indoor temperature in different seasons was revealed.It is concluded that the phase change heat storage ventilation technology is suitable for the transition season and summer in Hefei,and the phase change heat storage technology is more suitable for winter.Phase change heat storage technology has a positive effect on reducing the indoor temperature amplitude throughout the year and stabilizing the indoor thermal environment.In spring and autumn,the indoor uncomfortable hours of phase change ventilation coupling technology,ventilation technology and phase change heat storage technology were reduced by 24.6%,20.9%and 14.5%respectively compared with the reference group.（4）The influence law of phase change technology,ventilation technology and phase change ventilation coupling technology on building energy consumption is obtained.In spring,the total building load of phase change technology,ventilation technology and phase change ventilation coupling technology decreased by 0.42%,2.74%and 3.33%compared with the reference group,respectively.The building load decreased by 2.9%by adding ventilation technology on the basis of phase change heat storage technology.In summer,compared with the reference group,the three cooling technologies decreased by 1.7%,4.6%and 4.8%,respectively.In autumn,compared with the reference group,it decreased by 1.4%,1.93%and 3.40%,respectively.In winter,the building heat load using phase change heat storage technology decreased by 9.6%compared with the reference group.In transition season and summer phase change heat storage ventilation technology energy saving potential>ventilation technology>phase change heat storage technology,and in winter phase change heat storage technology is more conducive to reducing building heat load.Figure[48]table[13]reference[90]...