Impact of High-Voltage Discharge After-Treatment Technology on Diesel Engine Particulate Matter Composition and Gaseous Emissions

Abstract

Diesel particulate matter (DPM) and oxides of nitrogen (NOx) are the emissions from diesel engines (compression ignition engines) of the most concern and are currently strictly regulated. In this work, we present an alternative diesel emission control technique to assist in further emission reduction. An experiment-oriented study on diesel engine emission abatement using low-power, low-frequency, high-voltage discharge (HVD) treatment was carried out in a laboratory-scale reactor with whole diesel engine exhaust gas. A dielectric barrier discharge (DBD) reactor was used in direct contact with diesel exhaust gas at atmospheric temperature with an input energy density between 200 and 400 J/L. An investigation of the direct effect of the high-voltage discharge reactor on the diesel exhaust gas treatment was carried out to characterize both diesel particle and gaseous emissions. The proposed HVD system demonstrated up to 95% particulate matter reduction by mass or 64% reduction by number, and 63% reduction of the diesel soot particle geometrical mean diameter by HVD-generated O3 oxidation. Thermogravimetric analysis revealed the significant change in the diesel soot compositions and oxidation characteristics. HVD-treated particulate matter demonstrated a lower reactivity in comparison to untreated soot. Gas composition analysis indicated the generation of free radicals (e, O, OH, O3, and N) by the HVD system, as mainly indicated by the increase of the NO2/NO ratio and concentration of CO and O2. The pattern of CO2 reduction while CO and O2 increased indicated the dissociation of CO2 by HVD. Free radicals generated by HVD directly affected DeNO, DeNOx, NO2/NO ratio, and CO and CO2 selectivities.

Insight into Nanoparticle-Number-Derived Characteristics of Precharged Biodiesel Exhaust Gas in Nonthermal Plasma State

“…In addition, the particle concentration results show a great reduction performance for the small size particles, which indicates that the NTP charger can cause the low-temperature oxidation of PM . The amount of PM in terms of carbon is reduced by plasma chemistry reactions through the ionization of nitrogen dioxide (NO 2 ), a component of NO x . The possible mechanisms of PM and NO x reduction are proposed as follows. ,, These reaction mechanisms can proceed at low temperatures (under 200 °C).…”

“…The amount of PM in terms of carbon is reduced by plasma chemistry reactions through the ionization of nitrogen dioxide (NO 2 ), a component of NO x . The possible mechanisms of PM and NO x reduction are proposed as follows. ,, These reaction mechanisms can proceed at low temperatures (under 200 °C). In addition, NO 2 can also be converted to nitrogen for PM reduction reactions.…”

“…35 The amount of PM in terms of carbon is reduced by plasma chemistry reactions through the ionization of nitrogen dioxide (NO 2 ), a component of NO x . 36 The possible mechanisms of PM and NO x reduction are proposed as follows. 31,36,37…”

The Influence of Direct Non-Thermal Plasma Treatment on Soot Characteristics under Low Exhaust Gas Temperature

“…An amount of ionic and excited species in plasma with sufficient energy to collide and break the stable molecular structure of the particles passing through it [17]. However, in the nonthermal plasma system, which occurs when the kinetic energy of electrons or temperature is higher than the kinetic energy of gas molecules outside (around ambient temperature) [18][19][20], electrical energy is transmitted to the electrons, causing the production of free radicals such as N, O, HO2, and OH [21]. Due to this characteristic, nonthermal plasma (NTP) has a high energy efficiency [22].…”

Establishment of Repeated In Vitro Exposure System for Evaluating Pulmonary Toxicity of Representative Criteria Air Pollutants Using Advanced Bronchial Mucosa Models

“…In urban areas, exhausts from diesel and gasoline vehicles constitute a major portion of PM and have been suspected of increasing the risk of cardio-pulmonary diseases. In a very recent study, Wongchung et al (2021) demonstrated that diesel particulate matter (DPM) and oxides of nitrogen (NOx) are the emissions from diesel engines (compression ignition engines) of the most concern and are currently strictly regulated [10]. It has been already reported by several air pollution researchers that diesel exhaust (DE) emissions are the major source of PM in the urban environment that contribute a very high numbers of ambient particles and a large reactive surface area, as well as the potential to deposit throughout the lungs [11,12].…”