Study On The Effect Of Double Diffusive Convection On The Heat And Salt Transport Law In A Salinity Gradient Solar Pond

In the environment of increasing shortage of energy,the use of new energy naturally concerned by the majority of scholars.Salinity gradient solar pond as a new type of solar energy conversion and utilization system,has the advantages of simple structure,low cost,environment friendly,non-pollution and a series of advantages.It has broad prospects for development.Therefore,the study of salinity gradient solar pond is one of solar energy utilization of new hotspots at home and abroad.Salinity gradient solar pond is typically a heat-salt double diffusive system,in the non-convective zone the temperature gradient and salinity gradient exist simultaneously.The key factor for the stable operation of the solar pond is the thermal and salt diffusion process caused by the temperature gradient and salinity gradient in the solar pond.In this paper,the non-convective zone of the salinity gradient solar pond in the steady state was taken as the research object.The numerical simulation and experimental study were carried out to analysis and study the process of the heat and salt migration in the non-convective zone.In the aspect of numerical simulation,the mathematical model of the non-convective zone of salt gradient solar pond was established,and the boundary conditions and initial conditions were defined and also verified the grid independence.The numerical results show that the solar pond in the steady state,in the non-convective zone the temperature and salinity were nearly linearly distributed,and had little change with the time;the velocity vector diagram shows that,there was the annular diffusion phenomenon in micro scale in the non-convective zone,it was diffusion layer.In addition,the non-convective zone mass flow rate was analyzed,which provides a reference for the maintenance of the gradient layer.In the experimental study,the heat and mass transfer process in the non-convective zone of the salt gradient solar pond was studied by building a small test bench.The experimental part mainly included two layers of experimental research and multi layers(i.e.,the non-convective zone of the solar pond)experimental study of the two parts.It can be got through the processing and analysis of experimental data that: when the salinity difference under the condition of constant,the temperature increases will accelerate the diffusion velocity of the salt in the fluid,the temperature difference is too large,the destruction of the salinity gradient in the non-convective zone also will speed up.During the experiment,also found that when the salinity gradient is constant,there is a maximum temperature gradient,it make the non-convective zone of the solar pond keeps stable state when the temperature gradient is not higher than the maximum value.In addition,when compared with the simulation results in the steady state,at the same time,the temperature and the salinity distribution were the same trend.They have a higher degree of coincidence.This paper through numerical calculation and experimental analysis of two studies found that study on the migration of heat and salt in the non-convective zone of the solar pond can provides reference and theoretical supports for the stable operation and maintenance of the salinity gradient solar pond.