Numerical Simulation Of The Convection And Diffusion Process Of The Discharge Of Hot Concentrated Brine In Desalination

Low temperature multi-effect distillation seawater desalination technology is used to produce high quality fresh water,however,it will produce hot concentrated brine at the same time.Whether the brine discharged into the sea will have an impact on the marine environment is urgent to study.In this paper,a numerical model is established by using the MIKE software to study the process of convection and diffusion,also heat and mass transfer process.The main research results are as follows:(1)The control equations of hydrodynamic,salinity and temperature convection and diffusion are established.Using the eddy viscosity model to describe the turbulent flow.The boundary conditions and the numerical method of MIKE3 flow model are introduced.(2)The model of ideal flume is designed.The results show that the surface and vertical distribution of the salinity and temperature are periodically changed in a certain range.The distribution of them are very similar,indicating that convection plays a leading role.In the vertical direction,the salinity and temperature will increase synchronously with depth.But when the depth increases,velocity decreases.(3)A three-dimensional hydrodynamic model of the Liaodong Bay is established.The calculation of tidal level is compared with the measured data.The results show that they are in good agreement.The numerical simulation results could reflect the change of the tidal current in the Liaodong Bay.The model is suitable for study the process of convection and diffusion of the concentrated brine.(4)Then,the convection and diffusion law of concentrated brine is studied.The results show that the increase of salinity and temperature is mainly concentrated in the maximum range of 4.58 km from coastline,and most of the area in Liaodong Bay has not been affected.The surface distribution of salinity and temperature is greatly influenced by the tidal flow and periodically change with the flow.The surface distribution of temperature and salinity is very similar,indicating that convection plays a leading role.In the vertical direction,the salinity and temperature value of the same surface position will be increase along with the depth,and will accumulate at the bottom plane.