Fog Droplet Collection by Corona Discharge in a Needle–Cylinder Electrostatic Precipitator with a Water Cooling System

Abstract

In this study, a needle–cylinder electrostatic precipitator with a water cooling system was designed to enhance the harvest of atmospheric water in wet flue gas. The effects of flow rate, temperature and particles on the collection of fog droplets were investigated. Meanwhile, the energy efficiency of water collection was analyzed at different voltages. The results show that the current decreases with the increase of air relative humidity under the same voltage, and the breakdown voltage increases obviously. Concurrently, by appropriately reducing the wet flue gas flow velocity, the residence time of fog droplets in the electric field can be increased, fully charging the droplets and improving the water collection efficiency. Moreover, experiments revealed that through decreasing the flue gas temperature, both the water collection rate and energy efficiency can be improved. In addition, the presence of particles in wet gas can improve the water collection rate by 5~8% at different discharge voltages. Finally, based on energy efficiency analysis, with the increase of voltage, although the water collection rate increased, the energy efficiency decreased.

Numerical simulation of the enhancing effect of micro–nano protrusions on electrostatic fog harvesting

“…Inspired by the efficient dust removal from barbed corona wire, decorating sharp discharge tips on the discharge electrode is a promising idea to optimize the electrostatic fog harvester. The enhancement effect of protrusions on the ionic wind discharge current has already been experimentally demonstrated, especially in the application of electrostatic precipitation [38,[40][41][42], fog harvesting [32] and so on. However, the enhancement mechanism at the microscopic level is less reported, which is what we are concerned with in this manuscript.…”

“…Although considerable excellent research has been carried out to improve fog harvesting efficiency [32][33][34], there are still some problems, such as high dependence on high voltages [26], complex structures [35,36] and expensive cost [8,37]. Therefore, a low-voltage, high-efficiency, simple and economical discharge method is urgently needed.…”

Ionic Wind Driven Fog Collection in Windless Environment

“…22,23 Corona discharge and cooling have been coupled to harvest the fog and water vapor in the wet flue gas. 24 The deposition efficiency depends on the Stokes number. In a windless environment, the wind velocity and St number are both zero.…”

“…An active fog collection approach by using the corona discharge and electric field has recently attracted much attention. − Droplets in the fog are charged by the corona discharge, and the deposition efficiency can be greatly enhanced (>1.0) by the electric field . A field experiment demonstrated that an electrostatic fog collector provides a 60% better fog collection rate than a standard mesh-like fog collector .…”

“…An overall fog collection efficiency of more than 90% was reported by using pillar arrays as the collection electrodes and wires as the repelling electrodes . Ionic wind generated by the corona discharge process was used to intercept the fog stream and capture fog droplets. , Corona discharge and cooling have been coupled to harvest the fog and water vapor in the wet flue gas …”