Electrostatic battery for emissions control (ESBEC): Further development and testing with diesel emissions

We recently developed a novel diesel emissions control device, Electrostatic Screen Battery for Emissions Control (ESBEC), where an electrostatic mechanism removes diesel exhaust particles onto metal screens. In this study, we made the following improvements to the initial ESBEC’s design: (1) used metal collection screens of different porosity for a more even distribution of captured diesel exhaust throughout ESBEC, (2) redesigned screen holders for easy assembly of ESBEC, (3) heat-resistant materials were used to build the current model, which is 3 in. in diameter and 4 in. in length. ESBEC was investigated in a laboratory to optimize the screen porosity and configuration. Then, in the field, it was challenged with diesel particulate matter (DPM) exhausted from a diesel electric power generator. The DPM mass concentrations produced by the generator varied from 38 to 187 mg/m3, and air flow rates passing through ESBEC varied from 219 to 410 L/min. The testing was intermittently performed over 49 h. In addition, ESBEC’s particle collection efficiency was compared to that of a traditional diesel particulate filter (DPF). We also explored various washing methods to effectively remove DPM captured by ESBEC. When challenged with DPM, ESBEC showed collection efficiency of ∼100% for 26 h, during which 60 g of DPM was captured. For comparison, the collection efficiency of DPF was ∼77%. After the total run time of 46 h, the collection efficiency of ESBEC decreased to CARB (California Air Resources Board) Level 3 (85%), with 102 g DPM accumulated. When ESBEC was operated beyond 46 h, its collection efficiency was <85%. However, washing screens for 5 min in isopropyl alcohol restored the collection efficiency to 86%. Future studies will examine the performance of ESBEC when it is installed in an actual diesel-powered vehicle.