Sadeghpour Abolfazl, Oroumiyeh Farzan, Zhu Yifang, Ko Danny D, Ji Hangjie, Bertozzi Andrea L, Ju Y Sungtaek
Department of Mechanical and Aerospace Engineering, University of California Los Angeles, Los Angeles, USA.
Department of Environmental Health Sciences, University of California Los Angeles, Los Angeles, USA.
J Air Waste Manag Assoc. 2021 Jul;71(7):851-865. doi: 10.1080/10962247.2020.1869627. Epub 2021 May 18.
Wet electrostatic precipitators (WESP) have been widely studied for collecting fine and ultrafine particles, such as diesel particulate matter (DPM), which have deleterious effects on human health. Here, we report an experimental and numerical simulation study on a novel string-based two-stage WESP. Our new design incorporates grounded vertically aligned polymer strings, along which thin films of water flow down. The water beads, generated by intrinsic flow instability, travel down the strings and collect charged particles in the counterflowing gas stream. We performed experiments using two different geometric configurations of WESP: rectangular and cylindrical. We examined the effects of the WESP electrode bias voltage, air stream velocity, and water flow rate on the number-based fractional collection efficiency for particles of diameters ranging from 10 nm to 2.5 μm. The collection efficiency improves with increasing bias voltages or decreasing airflow rates. At liquid-to-gas (L/G) as low as approximately 0.0066, our design delivers a collection efficiency over 70% even for fine and ultrafine particles. The rectangular and cylindrical configurations exhibit similar collection efficiencies under nominally identical experimental conditions. We also compare the water-to-air mass flow rate ratio, air flow rate per unit collector volume, and collection efficiency of our string-based design with those of previously reported WESPs. The present work demonstrates a promising design for a highly efficient, compact, and scalable two-stage WESPs with minimal water consumption.: Wet Electrostatic Precipitators (WESPs) are highly effective for collecting fine particles in exhaust air streams from various sources such as diesel engines, power plants, and oil refineries. However, their large-scale adoption has been limited by high water usage and reduced collection efficiencies for ultrafine particles. We perform experimental and numerical investigation to characterize the collection efficiency and water flow rate-dependence of a new design of WESP. The string-based counterflow WESP reported in this study offers number-based collection efficiencies >70% at air flow rates per collector volume as high as 4.36 (m/s)/m for particles of diameters ranging from 10 nm - 2.5 μm, while significantly reducing water usage. Our work provides a basis for the design of more compact and water-efficient WESPs.
湿式静电除尘器（WESP）已被广泛研究用于收集细颗粒和超细颗粒，如对人体健康有有害影响的柴油颗粒物（DPM）。在此，我们报告了一项关于新型基于串的两级WESP的实验和数值模拟研究。我们的新设计采用了接地的垂直排列聚合物串，水流沿着这些聚合物串向下流动。由内在流动不稳定性产生的水珠沿串向下移动，并在逆流气流中收集带电粒子。我们使用两种不同几何构型的WESP进行了实验：矩形和圆柱形。我们研究了WESP电极偏置电压、气流速度和水流速率对直径范围为10纳米至2.5微米颗粒的基于数量的分级收集效率的影响。收集效率随着偏置电压的增加或气流速率的降低而提高。在液气比（L/G）低至约0.0066时，即使对于细颗粒和超细颗粒，我们的设计也能实现超过70%的收集效率。在名义上相同的实验条件下，矩形和圆柱形构型表现出相似的收集效率。我们还将基于串的设计的水-空气质量流量比、单位收集器体积的空气流速和收集效率与先前报道的WESP进行了比较。目前的工作展示了一种具有前景的设计，即一种高效、紧凑且可扩展的两级WESP，其水消耗最少。：湿式静电除尘器（WESPs）对于收集来自各种来源（如柴油发动机、发电厂和炼油厂）的废气中的细颗粒非常有效。然而，它们的大规模应用受到高水用量和超细颗粒收集效率降低的限制。我们进行了实验和数值研究，以表征一种新型WESP设计的收集效率和水流量依赖性。本研究中报道的基于串的逆流WESP对于直径范围为10纳米至2.5微米的颗粒，在单位收集器体积的空气流速高达4.36（米/秒）/米时，基于数量的收集效率>70%，同时显著减少了水的用量。我们的工作为设计更紧凑和节水的WESPs提供了基础。
