Research And Engineering Application Of Water And Gas Two-phase Flow Spray Temperature Control Method For Concrete Pouring Surface

When concrete is poured in high temperature season,it is exposed to air after entering concrete surface.Because of the influence of temperature and solar radiation heat,there is heat transfer between the surrounding environment and concrete,which results in temperature recharge,leading to the pouring temperature and the highest temperature exceeding the standard.At present,the concrete surface spray is the main means of controlling the temperature of concrete bin.The main principle is:(1)through the spray on the concrete surface,the fog layer with a certain thickness can be formed on the concrete surface,which can block the solar radiation.(2)the droplet evaporates in the concrete surface and takes away the heat,so as to achieve the purpose of reducing the concrete surface environmental temperature.At present,the main ways of spraying concrete surface are air duct sprayer,flushing gun and mobile air duct sprayer.These spray methods have the following problems due to the defect of their own spray principle:(1)The atomizing particles is larger,and it is easy to form accumulated water in the concrete surface,affecting the mix proportion of concrete;(2)Due to the concentration of spray points,it is not suitable to cover the whole concrete surface;(3)Quantitative control of concrete surface environment cannot be carried out,and the cooling effect is not obvious.;(4)higher operating costs.Therefore,based on the existing problems of spray method,and based on the engineering practice,a complete set of intelligent spray technology for water and gas two-phase flow is developed,including hardware equipment,spray prediction model and software system.The main innovative achievements are as follows:(1)Developed a complete set of spray hardware equipment for water and gas two-phase flow,which is suitable for dam surface environment and combined with template structure.Based on the engineering climate conditions and construction conditions,according to the temperature control needs of the concrete surface,The design,development and integration of high-pressure gas supply device,high pressure water supply device,water gas two-phase flow spray device,water delivery pipeline,gas transmission pipeline and supporting structure were carried out,and a complete set of air-water two-phase flow spray hard equipment was formed,The spray system has the advantages of smaller atomized particles(less than 30 um),full coverage of warehouse surface,rapid installation and no influence on construction.(2)Set up a set of numerical prediction models for water and gas two-phase flow concrete surface spray,which mainly include the numerical prediction model of the prediction model of concrete temperature rise,atomization quantity of concrete surface,and the prediction model of water gas two-phase flow volume.Through real-time collection of concrete surface information,including data of temperature,humidity,wind speed,solar radiation intensity and temperature of concrete surface,the spray parameters(water requirement and gas requirement)were calculated according to the target temperature of concrete surface temperature control.The engineering application results showed that the prediction results of this model were good,and the error rate was less than 5%.(3)Designed a complete software system for water and gas two-phase flow spray,and realized automatic acquisition,real-time interconnection,intelligent analysis and feedback control of temperature control information.It mainly includes:1)the real-time automatic acquisition subsystem of the concrete surface microclimate;2)the real-time transmission subsystem of the concrete surface microclimate monitoring data;1)the spray control subsystem on the control surface;4)the real-time evaluation subsystem of information management and temperature control effect.Each subsystem integrates feedback to form a closed-loop system.(4)Relying on an Concrete Dam in Northeast China and a Large Water Conservancy Project in Guangxi,the first engineering application of concrete surface spray is realized.The spray temperature control method of water-gas two phase flow can reduce the average temperature of the warehouse surface by 10-15?,and the average casting temperature is increased by 2-2.5 ?.Finally,the water and gas two-phase flow spray system can effectively solve the shortcomings of the traditional spray method,and has broad application prospects,and has high popularization and application value.