Thermal Performance Optimization Analysis Of Building Exterior Walls Based On Thermal Insulation And Thermal Storage

With the improvement of building energy efficiency and people’s requirements for indoor thermal comfort,the unsteady thermal performance of building walls is receiving more and more attention.This article consists of six types of insulationenergy storage building walls by adding thermal insulation material(TIM),phase change material(PCM),and simultaneously adding TIM and PCM to multilayer wall and heterogeneous wall respectively.Based on the enthalpy method model and using MATLAB software,calculate the thermal performance of six types of walls with different influencing parameters under typical outdoor comprehensive temperatures in hot summer and cold winter regions.Taking the thermal resistance(or heat transfer coefficient),decrement factor and time lag as evaluation indicators,comprehensively summarizing the influence of parameter changes on the thermal performance of the wall.Exploring thermal performance optimization schemes for insulation energy storage walls,and proposing general design rules for multilayer and heterogeneous insulation-energy storage walls with good thermal performance.The main research work and achievements are as follows:(1)One-dimensional and two-dimensional enthalpy models were proposed and experimentally validated using the variable temperature hot box method to test PCM specimens and hollow blocks.The results indicate that the results indicate that the numerical simulation results are in good agreement with the experimental data,because the average values of standard error and maximum absolute error of one-dimensional enthalpy model are 0.63℃ and 2.77℃ respectively,and the standard error and maximum absolute error of the two-dimensional enthalpy model are below 1.7℃ and3.6℃ respectively.(2)Conduct a comprehensive analysis of the influencing factors of the three insulation-energy storage walls of multilayer wall,and summarize the influencing laws of each wall.The results indicate that the thermal performance of the wall can be improved by placing TIM\PCM separately on the outside\inside of the wall,reducing TIM thermal conductivity and increasing TIM layer thickness,increasing PCM latent heat and thickness,increasing PCM volume fraction within 50%,matching phase transition temperature with PCM actual temperature,reducing base wall thermal conductivity and increasing base wall heat capacity,etc.(3)Conduct a comprehensive analysis of the influencing factors of foundation wall and the three insulation-energy storage walls of heterogeneous wall,and summarize the influencing laws of each wall.The results indicate that the thermal performance of foundation wall and walls containing only TIM or PCM can be improved by reducing the thermal conductivity of the block material and increasing the heat capacity of the block material;the thermal performance of all walls can be improved by using appropriate hollow block construction configurations,increasing the latent heat and content of PCM,matching the phase change temperature with the actual temperature,and filling PCM in the holes near the indoor area of the block.(4)According to the above conclusions,the general design rules of multilayer and heterogeneous wall is summarized,and the wall in hot summer and cold winter and cold area is optimized and its suitability is analyzed.The results show that the temperature amplitude of the inner surface of each optimized wall is lower than 1℃,which improves the indoor thermal comfortableness.Compared with heterogeneous wall,PCM is more suitable for multi-layer flat wall.Compared with the cold area,the application of PCM in hot summer and cold winter area is more valuable.