Experimental Study On Photovoltaic Electrodialysis Desalination

The electrodialysis(ED)desalination has low requirements for energy supply stability,however,the energy consumption is relatively high.This paper proposed the photovoltaic electrodialysis desalination system with photovoltaic direct energy supply and energy storage system energy supply respectively.By theoretical analysis and experimental research,the performances of the photovoltaic electrodialysis desalination system under two energy supply modes were characterized.The energy utilization efficiency,fresh water production,energy consumption and water production cost of the system with different salt water concentrations,different flow rates,and different irradiation conditions were discussed.The key point of electrodialysis in the two modes of photovoltaic energy supply is the ability to match the energy consumption of the electrodialysis saltwater desalination system with the power generation capacity of the energy supply system.The optimized photovoltaic power and electrodialysis size match is 200 W,3000 m L capacity.It can realize the synergy work of energy input,fresh water production,and inflow and outflow.The main research work is as follows:1.The working principle of electrodialysis desalination was proved by Donnan membrane equilibrium theory.The mathematical model of photovoltaic electrodialysis was established,and the mass transfer process of electrodialysis desalination was analyzed.Two kinds of photovoltaic energy-assisted electrodialysis desalination systems were constructed to study the effects of different energy supply modes and different photovoltaic energy supply on different areas of electrodialysis desalination system.The effects of electrodialysis desalination systems on different voltages,different flows,and different concentrations are discussed.The results show that the higher the voltage,the lower the salt content in the solution.When the voltage is about 30 V,the salt content curve drops smoothly,the system works stable,the water production is 2800 m L,it takes 210 minutes,and the energy consumption is1.515 k W·h.When the critical value of 40 V is reached,concentration polarization occurs.Under the same voltage conditions,the desalination rate of the solution with aconcentration of 12.8 g/L is higher than that of the solution with a concentration of25.6 g/L,and the flow rate is inversely proportional to the desalination rate;under the same flow conditions,the voltage is proportional to the desalination rate.2.Analyze the effect of solar radiation intensity received by photovoltaic panels on daily freshwater production.The results show that when the irradiance reaches 400 W/m2,it takes 480 minutes to produce 2800 m L of fresh water below0.5%;when the irradiance reaches 600 W/m2,it takes 180 minutes;when the irradiance reaches 800 W/m2,it takes 160 minutes;when the irradiance reaches 1000W/m2,it takes 140 minutes.The average experimental irradiance was 764 W/m2,the production of 2800 m L took 173 minutes,and the energy consumption was 1.124 k W·h.It can be concluded that the same amount of water produced,the stronger the irradiance,the shorter the time required.3.The analysis of the charging and discharging curves of the energy storage system and the work of electrodialysis system show that the energy storage system effectively increases the sustainable working time of the electrodialysis desalination system.Under the system conditions,the desalination process can be guaranteed in the sunshine weather.Sustainable energy supply for more than 27 hours under poor weather conditions.