Technical note Reduction of aerosol particulates through the use of an electrostatic precipitator with guidance-plate-covered collecting electrodes Tsrong-Yi Wen a , Igor Krichtafovitch b , Alexander V. Mamishev a,c,n a Department of Mechanical Engineering, the University of Washington, Seattle, Washington, United States b Pacific Air Filtration Inc., Seattle, Washington, United States c Department of Electrical Engineering, the University of Washington, Seattle, Washington, United States article info Article history: Received 10 July 2014 Received in revised form 6 October 2014 Accepted 6 October 2014 Available online 23 October 2014 Keywords: ESP Holes Filtration efficiency Re-entrainment abstract This paper presents a novel particle-trapping mechanism that enhances the filtration efficiency of an electrostatic precipitator (ESP). Collecting electrodes are covered with guidance plates that have patterned holes. Gaps are intentionally left in-between the guidance plates and the collecting electrodes, so that particles can travel through these holes and sit inside the gaps. Guidance-plate-covered ESPs have up to 20% higher filtration efficiencies than traditional ESPs. The parametric studies show that the number of holes in the guidance plates has more influence on filtration efficiency and power consumption than the diameter of the holes. & 2014 Elsevier Ltd. All rights reserved. 1. Introduction Fine airborne pollutant particles, or particles smaller than 2:5 μm in diameter (PM 2.5 ), are considered as a source of risk for diseases, such as ischemic stroke and cardiovascular disease (Brook et al., 2010; Wellenius et al., 2012). Filtering these particles out of the air stream to improve air quality has gained considerable attention. For HVAC systems (heating, ventilation, and air conditioning), filters are used to improve indoor air quality and to protect components like fans and heat exchangers. From an energy saving standpoint, a filtration system saves a significant amount of energy when using electrostatic precipitators (ESPs), rather than fiber-based filters. This is because electrostatic precipitators have much lower pressure drop than fiber-based filters. Fiber-based filters are obstructively placed into the path of the airflow, whereas electrostatic precipitators have most components placed along the path of airflow. In other words, fewer obstacles obstruct the airflow in electrostatic precipitators than in fiber-based filters. Furthermore, as more and more particles accumulate on the fiber-based filters, the accumulated particles increase the resistance to the airflow, causing the fans to require more power to maintain a specific airflow rate (Edelman, 2008; Fisk et al., 2002; Railio & Makinen, 2007; Xu et al., 2007). For ESPs, the collected particles do not increase the resistance to the airflow as much as they do for fiber-based filters, because the collecting electrodes and the airflow direction are in parallel, and the surface areas of the collected particles are relatively small. ESPs can be generally grouped into two types, single-stage and two-stage. Single-stage ESPs charge and collect particles at the same time, whereas two-stage ESPs charge and collect particle at separated sections (Mizuno, 2000). When compared to Contents lists available at ScienceDirect journal homepage: www.elsevier.com/locate/jaerosci Journal of Aerosol Science http://dx.doi.org/10.1016/j.jaerosci.2014.10.002 0021-8502/& 2014 Elsevier Ltd. All rights reserved. n Corresponding author at: Department of Electrical Engineering, the University of Washington, Seattle, Washington, United States. E-mail addresses: tywen@u.washington.edu (T.-Y. Wen), mamishev@u.washington.edu (A.V. Mamishev). Journal of Aerosol Science 79 (2015) 40–47