Study On The Heat Collection And Cooling Characteristics Of Solar Collecting Pavement

The asphalt pavement absorbs solar radiation,and the local temperature inside the pavement can reach 70℃ in summer.High temperature causes aging and ruts,which not only affects the performance of the pavement,but also exacerbates urban heat island effects.In recent years,the solar collecting pavement(SCP)has received widespread attention.In summer,the SCP collects and stores the heat form asphalt pavement to reduce the temperature of the pavement and prevent high temperature diseases on the road.In winter,the system can release energy for snow melting.Road paceing technology is of positive significance for the development and utilization of solar energy,the sustainable development of the pavement,and the improvement of the urban heat island effect.To this end,this paper focuses on the heat collection-cooling performance of SCP and the impact on urban small climate conditions.First of all,the experimental system in the natural environment was constructed,and the 3D digital heat transfer model of SCP and ordinary asphalt pavement was developed,and the numerical model was verified by the obtained data.Then,on the impact of parameters,analyze the effects of thermal parameters of pavement materials,different pipeline materials,thermal exchange system structure parameters,fluid operating parameters,environmental climate parameters on the thermal performance of SCP,and use sensitive analysis methods to study the degree of impact on system performance.Finally,the 3D transient number model of the coupling urban canyon was developed,which evaluated the effect of SCP to alleviate the effect of the city heat island.The results of environment experiments show that in the summer,the temperature of ordinary asphalt pavement can reach up to 72.5 ° C,while the fluid heat collecting system can effectively reduce the temperature of the pavement and reduce 17 ° C.The results show that the increase of road thermal conductivity,road radiation absorption,fluid mass flow rate,solar radiation and ambient temperature can improve the heat collection efficiency of the coefficient.The increase of asphalt mixture density,pipe spacing,pipe buried depth,initial inlet temperature and wind speed leads to the decrease of heat collection efficiency.Increasing the pipe diameter can slightly improve the heat collection efficiency when the pipe velocity remains constant,but the effect is limited.The heat collection effect of metal pipes such as copper pipes is better than that of plastic pipes.With the increase of pavement thermal conductivity,radiation absorption,density,pipe diameter,mass flow rate and ambient temperature,the total heat output of pavement decreases gradually.The increase of pipeline spacing,pipeline depth,initial water temperature,solar radiation and wind speed leads to the gradual increase of the total heat output of the pavement.The increase of wind speed leads to the decrease of the pavement temperature,but the increase of the convective heat output of the pavement is greater than the decrease of the heat output of the pavement temperature.Therefore,the total heat output of the wind speed increases.The results of parameter sensitivity analysis show that the ambient temperature is the most important parameter affecting the heat collection performance,the road radiation absorption rate is the most important parameter affecting the total heat output of the road,and the pipe structure parameters have no significant influence on the heat collection performance and the road heat output.The application of SCP in urban canyon pavement shows that system collects the most heat in summer,but the heat collection efficiency is the lowest.The maximum pavement temperature of SCP in spring,summer and autumn decreased by 14℃,19.9℃ and 12℃ respectively.For urban pavement with fluid heat collection system,the sensible heat release of pavement surface can be reduced by 47.41%,60.37%,52.46% and48.62% in spring,summer,autumn and winter,respectively.Although the heat output is the largest in summer,the reduction range is also the largest.In summer,the heat collection system can reduce the air temperature 1.5m above the road surface by about 1.1℃.