| With the rapid development of economy and the increasing improvement of people’s living standards,people’s requirements for air quality in buildings are becoming higher and higher.At the same time,the proportion of building energy consumption in terminal energy consumption is also increasing.The proportion of building energy consumption in terminal energy consumption in China also reaches nearly one third.The research on building energy saving and thermal comfort has attracted wide attention at home and abroad.The use of renewable energy is an effective measure to achieve building energy conservation and improve indoor air quality.Solar wall is a method to control and regulate indoor thermal environment by using solar energy,a renewable energy.However,solar energy is intermittent and unstable,which makes heating by solar energy have the characteristics of periodicity and uncertainty.Phase change heat storage technology can store heat by phase change materials and utilize latent heat released in the process of phase change,which can solve the contradiction between the time and space of heat supply.In this paper,the ventilation,heat transfer and auxiliary heating characteristics of phase change solar wall are studied by experiment and numerical simulation.A new type of solar energy wall experimental system was built.The indoor air temperature,outdoor meteorological parameters,collector surface temperature,air passage temperature and wind speed were tested in winter in Yuci District of Jinzhong City,Shanxi Province.The auxiliary heating performance was analyzed and studied in detail.A three-dimensional numerical model of phase change solar energy wall was established and tested.The validity of the numerical simulation is verified by the test data,and the performance under different phase transition temperatures in winter is studied.The experimental results show that:(1)Phase change solar energy wall can effectively prolong the auxiliary heating time,and has a good role of heat storage and auxiliary heating.The test results show that closing the inner upper and lower air outlets at about 2 o’clock in winter and opening them at 1-2 o’clock after sunrise can improve the thermal efficiency and heat storage,and achieve better heating effect.(2)The temperature of phase change storage solar wall system is more stable than that of the solar wall system without phase change paraffin.The maximum temperature of the heat absorbing surface of the phase change material without phase change paraffin is higher than that of the phase change paraffin system,while the lowest value is lower and the temperature fluctuation is larger.Therefore,the use of phase change material can make the indoor temperature fluctuation smaller.(3)As far as time-sharing ventilation rate is concerned,the maximum ventilation rate of unloaded phase change materials is 2.62 times that of filled phase change materials,and the ventilation rate of unloaded phase change materials is large at noon,but in the afternoon,the air volume decreases rapidly and does not have continuity,so the ventilation effect of filled phase change materials fluctuates more smoothly.(4)The heat supply of phase change solar wall is concentrated between 9:00 and 2:00,and after 2:00 there will be a negative value,the peak value of the whole day will appear around 13:00;while the heat supply of the unfilled phase change material system is mainly concentrated between 10:00 and 19:00,the rest of the time is close to zero,and the peak value of the whole day will appear around 12:00;the total heat supply of phase change solar wall is 29.7% more than that of the unfilled phase change material.Three-dimensional numerical simulation results show that:(5)In the endothermic stage,the use of phase change materials with high phase change temperature will make the endothermic surface temperature higher,while the use of phase change materials with low phase change temperature will restrict the increase of the endothermic surface temperature of phase change wall;in the exothermic stage,the use of phase change materials with high phase change temperature will make the wall temperature drop faster,while the use of phase change materials with low phase change temperature will make the temperature drop trend more stable.(6)The ventilation volume of the phase change solar wall system with higher phase change temperature is larger in the rising stage of temperature,and a turning point occurs at 19:00 in the decreasing stage of temperature.After that,the ventilation volume of the phase change material with higher phase change temperature decreases faster,while the ventilation volume of the system with lower phase change temperature decreases more gently.(7)In the rising stage of temperature,the time-sharing heat of phase change solar wall system with large phase change temperature will be larger than that of phase change solar wall system with low phase change temperature;before the temperature becomes stable in the falling stage,the time-sharing heat with large phase change temperature will be larger,but the time-sharing heat drop rate with high phase change temperature will be larger than that with low phase change temperature;after 19:00,the time-sharing heat value of phase change solar wall system with large phase change temperature will be faster.A system with a lower speed and lower phase transition temperature. |
