Experimental Research On Mass Transfer In A Reverse Electro-Dialysis Stack

In recent years,the state has vigorously promoted energy-saving and emission-reduction technologies.At the same time,a large amount of industrial waste heat cannot be used effectively.According to statistics,waste heat generated in industrial production accounts for approximately 17% to 67% of the total combustion heat of fossil fuels.And the available waste heat is as high as 60%,which has great potential for development.Converting waste heat resources into electric energy is an effective way to achieve it.At present,there are relatively mature technologies that include organic Rankine cycle power generation technology,lowtemperature steam turbine power generation technology,and semiconductor thermoelectric power generation technology.However,there are still areas where they cannot do anything.The group proposed a new power generation technology,which mainly uses the residual heat as a low-temperature heat source,and uses a multi-effect distillation technology to separate the solution into concentrated and light solutions.The reverse electro-dialysis technology is then used to convert the solution salt difference energy into Electrochemical potential energy,so the entire device is also divided into thermal separation part and reverse electro-dialysis power generation part.Since the power source of the battery is mainly the mass transfer of two different concentrations of solution,the degree of mass transfer also affects the output voltage of the battery.Therefore,the internal mass transfer of the battery is one of the most important factors that affect the performance of the battery.At the same time,the conversion relationship between conductivity and concentration of strong electrolyte solution was also studied.In this paper,NaCl and other strong electrolyte solutions are used as the working fluid to study the effect of the loop current and working solution concentration on the internal mass transfer of RED in the case of a closed circuit.The open cell voltage,cell terminal voltage,the permeation coefficient of the ion membrane,ion migration,water infiltration rate and ion diffusion rate are selected to analyze the mass transfer conditions.Based on the experimental results,the following conclusions are drawn: Within the range of 5 mol/L,there is a good linear relationship between the conductivity of NaCl and LiCl and the cubic root of the concentration,and the concentration can be directly calculated from the conductivity;for a fixed working solution,the stack Internal ion migration,water permeation rate,cell terminal voltage,and solute diffusion rate all increased with increasing solution concentration,and the permeation coefficient of the ion membrane decreased with increasing solution concentration.When the concentration of the solution is constant,the ion migration and solute diffusion rate in the reactor increase with the increase of the stack output current,and the battery terminal voltage and water infiltration rate decrease as the current increases.The permeation coefficient of ion membranes is different in different working solutions.