The Research On Design Method Of Rain Spraying,Evaporating And Cooling System For Pavement In Hot And Humid Climate

With the advancement of national urbanization,a large number of surface vegetation has been destroyed,and the surface area of hardened urban areas has continuously increased,which has affected urban climate characteristics,leading to an increasingly serious problem of“hydrological effects”and“heat island effects”.In this paper,a rain spraying,evaporating and cooling system for pavement is designed for the high temperature phenomenon of urban pavement.The purpose is to reduce the temperature of outdoor hardened pavement by using rainwater,alleviate the erythema of urban heat island,and improve the outdoor thermal environment.The main work and research results of the paper are as follows:(1)In this paper,a rain spraying,evaporating and cooling system for pavement is designed.Combining with the meteorological characteristics of hot and rainy areas in hot and humid areas,the paper analyzes the regional adaptability of related technologies such as rainwater collection,road-spraying and cooling,and gives the design and calculation reference for the main equipment of the system.(2)The main factors affecting pavement temperature and evaporation rate were studied.By establishing the calculation model of each heat in the thermal equilibrium equation of the pavement and combining with the actual measurement results of the road temperature in summer in Guangzhou,the main factors influencing road surface temperature are solar radiation,followed by air temperature.During sunny or cloudy summer days in Guangzhou,during the period from 10:30 to 16:00,the temperature of dry asphalt pavement is generally higher than50°C.During this period,the watering operation is performed.The theoretical vaporization latent heat obtained by calculating the solar radiation intensity and measured data is obtained.The average difference in heat exchange capacity can reach-58.28 W/m~2,and the surface temperature after water showering can be significantly reduced,and the cumulative calculated evaporation amount is 8.76 mm.(3)Measured the decrease of the pavement temperature after the spraying operation.Based on the measured results of dry roads,the paper further conducted outdoor road watering test on the pavement.The test results show that the average asphalt pavement temperature can be reduced by about 11.7°C,the maximum cooling rate can reach 15.2°C,and the effect of cooling the pavement temperature can be significant after 5 to 30 minutes of spraying operations during the summer noon from 11:00 to 15:30.Finally,by comparing the duration of cooling,the absolute value of maximum cooling temperature difference,and the accumulated time cooling value of each working condition after watering,from the view point of cooling efficiency and water saving,paper establishes a system operation scheme for spraying and cooling temperature of dry asphalt pavement in summer in Guangzhou.