Plasma-enhanced electrostatic precipitation (PE-ESP) of restaurant smoke emissions

The remediation of nanoscale particulate matter generated during restaurant cooking processes presents a unique challenge, characterized by higher flow rates than most engines but at significantly lower pollutant concentrations. As such, it combines the worst aspects of both scenarios. We present a novel solution to this persistent challenge using transient plasma generated by high-voltage (20 kV) nanosecond pulse discharge. This approach has recently demonstrated potential for enhancing electrostatic precipitation (ESP) in capturing oil-based aerosol particles from restaurant emissions and diesel particulates.(Jang, Yoo et al. 2023) However, prior studies have been limited to small-scale systems operating at low flow rates (~ 2.8 CFM, i.e., 0.0013 m³/s). Here, we report particulate matter (PM) mass concentrations plotted over 7-min cooking cycles with 24 hamburgers at 1000X higher flow rates than those reported previously. At flow rates of 2000 and 3000 cubic feet per minute (CFM), i.e., 0.94 m³/s and 1.416 m³/s, we achieve 93.7% and 86.9% reduction in PM, respectively. This system uses a total of 805 Watts of electrical power, which is less than 5% of a typical rooftop blower power (i.e., 18 kW). This system provides the additional benefit of reducing odor. The PE-ESP enables the system to operate at significantly higher flow rates (3000 CFM, i.e., 1.416 m³/s) than current filter-based technologies without creating a large backpressure on the fan (i.e., blower). In fact, our system produces a pressure drop of just 0.85 inches of water gauge (inwg) (212 Pa) at 2000 CFM (0.94 m³/s) and 1.91 inwg (476 Pa) at 3000 CFM (1.416 m³/s), which is considerably lower than current filter-based technologies and well below the blower limit, which can only tolerate a pressure drop of up to 10 inwg (2494 Pa) and represents a relatively firm design constraint. This plasma-enhanced approach demonstrates the potential for deploying such a system to restaurants to improve the efficacy of the remediation of smoke.