Thermal Performance And Structural Optimization Research Of A Wood Structure With Phase Change Tubular Wall

The application of phase change heat storage technology in building envelope can change the heat transfer characteristics of wall and reduce the energy consumption of building operation.Wood structure wall has been paid more and more attention because of its strong heat insulation and flexible design.In this paper,a kind of phase change tube wall of wood structure coupled with solar heat collection is proposed.The heat transfer efficiency of phase change material(PCM)is improved by uniformly inserting fin.Based on the numerical simulation method,the influences of PCM layer thickness,inline tube diameter,tube spacing and fin geometric parameters on the comprehensive performance of the wall were explored.Combined with sensitivity analysis and NSGA-Ⅱ algorithm,the high sensitivity parameters of the wall(fin number,PCM thickness and pipe diameter)were optimized.The main conclusions are as follows:(1)A kind of phase change tubular wall of wood structure coupled with solar heat collection is designed.Through the simulation analysis of FLUENT,the following results are obtained:Compared with the ordinary wood wall,the maximum temperature of the inner surface of the wall is 14℃higher than that of the ordinary wood wall in the water supply stage.After the water supply is stopped,the temperature of the wall slowly decreases and is still 7℃higher than that of the room.The average heat flux of 24 h is82.4 W/m2,and the heating effect is good;(2)The influence law of the internal physical parameters of the wall on the comprehensive performance of the wall is explored.The increase of the average heat flux on the inner surface of the wall slows down with the increase of the PCM thickness.The utilization rate of PCM is the highest under the condition of 30 mm,and the payback period of phase change wall under 25 mm is the shortest.In this study,the optimal interval of PCM layer thickness of the wall is 25-35 mm;(3)The influence of tube diameter and tube spacing on wall thermal performance is analyzed.The results show that the larger the pipe diameter,the higher the wall temperature during water supply,and the lower the wall temperature after water supply is stopped.In this study,the optimal interval of pipe spacing was 105-115 mm,and the optimal interval of inline pipe diameter was 20-25 mm.The optimal thickness,length and number of fins are determined to be 3-5 mm,80 mm and 20-25,respectively;(4)The response surface method was used to construct the regression equation between the highly sensitive parameters and the optimization objective.NSGA-Ⅱ algorithm was used to call the response surface model to carry out the optimization study,and the Pareto frontier of the optimization scheme was obtained.TOPSIS method was used to select the optimal ten schemes of theoretical phase-change wall,in which the PCM thickness was 31.5 mm.The pipe diameter was 24.9 mm,the number of fins was 25,the average heat flux was 91.36 W/m~2,and the utilization rate of PCM was 83.39%.