Study On The Law Of Heat And Salt Transport In Salt Gradient Solar Pond Based On Lattice Boltzmann Method

As a solar thermal conversion system,the salt gradient solar pond integrates heat accumulation and heat storage,which brings a lot of convenience to human life.The double diffusion of heat and salt exists in the solar pond,and the complicated heat and mass transfer mechanism is involved in the fluid flow.The study of the double diffusion natural convection phenomenon provides an important theoretical basis for maintaining the stability of the solar pond and increasing the heat storage capacity of the solar pond,and plays a guiding role in the actual construction of the solar pond.Considering the Soret effect and Dufour effect,the Lattice Boltzmann method is a hot research topic in recent years.Therefore,this paper uses C++to write a program,taking the two effects into account,to study the double diffusion phenomenon in the salt gradient solar pond.The specific research contents are as follows:Based on Boussinesq hypothesis and considering Soret effect and Dufour effect,the double distribution function is extended to multi-distribution function model.The coupling of velocity field,temperature field and concentration field is realized.The independence of grid and the correctness of program are verified.The effects of Soret effect and Dufour effect on temperature diffusion and concentration diffusion are studied.The results show that Soret effect promotes the diffusion of temperature and concentration,Dufour effect inhibits the diffusion of temperature and accelerates the diffusion of concentration,and Soret effect influences the temperature field and concentration field of salt gradient solar pond more than Dufour effect obviously,when the buoyancy lift ratio is less than 1,the Soret effect plays the main role,and when the buoyancy lift ratio is greater than 1,the Dufour effect plays the main role.Based on the multi-distribution function model,considering the Soret effect and Dufour effect,the effects of heat transfer mode transition,the relative size of heat and mass diffusion,the size of solar pond and the number of Non-Convective Zone on the double diffusion in a salt gradient solar pond are studied under certain conditions,and the law of dynamic transfer of heat and salt and the change of Non-Convective Zone thickness in a salt gradient solar pond are also studied.The results show that when the Rayleigh number increases from 5×10~5 to 10~6,the heat transfer mode will change from heat conduction to heat convection.The heat diffusion speed of the solar pond is faster than that of mass diffusion,and the heat storage capacity will increase with the increase of the size of the solar pond.The optimal number of Non-Convective Zone is8,and the thickness of Non-Convective Zone in the solar pond will decrease with the increase of time.