An Electrostatic Enhanced Highly Efficient Self-powered Fog Collection System Driven By Triboelectric Generators

Although over 70%of the Earth’s area is covered by water,many arid regions in the world still face water scarcity problems due to extremely uneven distribution of water resources.Collecting fog to obtain fresh water is a feasible method and has been successfully implemented in some countries along the Pacific coast of South America and southern Africa.Adding an electric field to a fog collection system is an effective method to improve the efficiency.Charged droplets are subjected to electric field forces in the electric field,thereby overcoming the airflow following effect under low Stokes number conditions and improving the capture rate of droplets by the metal mesh.As a portable energy collection and conversion device,triboelectric generators have become a research hotspot in recent years.It can provide sufficient electric field due to its high voltage output.Thus it is an ideal power source for electric field enhanced fog collection devices.A high-performance fog collection system is designed in this paper that utilizes a triboelectric generator to provide an external electric field to improve fog collection efficiency.Firstly,we investigated the fog collection performance of metal mesh by directly applying an electric field.Under a fog flux of 333 g/(m~2·min),the amount of fog collection per unit area increases by 3.43 times when the electric field intensity is12 k V/cm,compared to when no electric field is applied.By constructing a multi electrode matrix,the fog collection efficiency is further improved.The amount of fog collection per unit area is 3.76 times as much as that under single electrode conditions,and 16.7 times as much as that no electric field is applied,the amount of fog collection per unit area is as high as 15360 g/m~2.During the entire fog collection process,the emission electrode and the metal mesh are not connected,thus the fog collection performance is only affected by voltage,and the positive or negative emission electrodes do not affect the enhancement effect of fog collection performance.Triboelectric generator has the output characteristics of high voltage and low current,which just matches with it.Therefore,it is a feasible method to enhance the fog collection performance by using Triboelectric generator.In order to achieve the self-powered fog collection function,we have designed a wind driven rotating triboelectric generator to provide an external electric field for the fog collection system.Within a wide wind speed range which from 3 m/s to 21 m/s,the generator can operate normally.When the wind speed is 21 m/s,its open circuit voltage can reach 400V and short circuit current can reach 34μA.The instantaneous maximum output power is 4.275 m W.The voltage output of the triboelectric generator is rectified and connected to the electrode array as the power source for the electric field enhanced fog collection system.The amount of fog collection per unit area is increased by about 95%.Under poor fog conditions,the amount of fog collection per unit area is increased by approximately 1.3 times.And this effect can be achieved only with lower wind force.In addition,since this enhancement effect is only provided by the electric field,a small triboelectric generator can provide sufficient voltage for a larger working surface.This high-efficiency self driving fog collection system based on triboelectric generators has excellent application prospects.