Experiment And Simulation Of Iron Diffusion At End Of Water Distribution System

Urban water supply security is an important issue that relates to the lives and health of the people,after years of use,metal pipes will have different degrees of corrosion,iron release is an important reason for deterioration of water quality,which will lead to "red water".It affects the perception of drinking water,causing complaints from users,while excessive intake of drinking water can also cause the user's health problems.The water quality model is an important tool to realize water quality monitoring and control it.EPANET toolkit is an important method of hydraulic water quality modeling.However,EPANET does not consider the release of water quality and the diffusion effect of iron at the end of water supply pipe network which Resulting in inaccurate grasp.In order to study on this phenomenon,we revise EPANET and obtain a more accurate water quality model.In this study,we designed diaphragm technique device and calibrated the constant of the membrane reactor using the known KCL.The average of the experiments is the most Membrane pool constant.The diffusion coefficient of ferrous chloride at 288.15 K,293.15 K and 298.15 K was measured by membrane constant and complexometric titration method to obtain the integral diffusion coefficient as the initial value.The differential diffusion coefficient was obtained by least squares method on the expression of concentration.Based on the differential diffusion coefficient determined by the above experiment,the CFD numerical model is established,and the turbulent field is used as the coupling field of the material migration field.The accuracy of the CFD numerical model is calibrated by setting seven different working conditions at three temperatures.At the same time,the same situation is simulated by EPANET,and the diff erence between them is considered.The CFD numerical model can be reflected to a certain extent situation,while EPANET need some amendments.Using the CFD numerical model at 288.15 K,293.15 K,298.15 K,the effects of the diffusion on the iron diffusion were studied by the end length,the end diameter,the diameter of the end connecting pipe,the velocity of the terminal connected pipe and the end water concentration.In order to facilitate the practical engineering application,this study uses a new multivariate nonlinear regression method to determine the best regression model of a single independent variable by univariate nonlinear regression,and the superposition of the optimal model of multiple independent variables.The initial value of the linear regression is followed by an iterative analysis of the empirical model at three temperatures.The resulting multivariate nonlinear regression model is fast and accurate in the domain interval.In this paper,the engineering application is taken as an example.The hydraulic model of the pipeline network is established by using the topology data of the pipeline network.The accuracy of the hydraulic model of the pipe network is calibrated.Based on the hydraulic model of the pipe network which conforms to the relevant standard,the water quality modeling of the water supply network is carried out on the pipe network of DG city with improved EPANET.The results show that the improved model EPANET can more accurately describe the real distribution of iron in the water supply network,with a wide range of application value.