Real diesel engine exhaust emission control: indirect non-thermal plasma and comparison to direct plasma for NOX, THC, CO, and CO2

Experimental evaluation of the effect of ozone treatment on the oxidation and removal of dry soot deposits of the exhaust gas recirculation system

The integration of alternative energy sources as a replacement for fossil fuels across various industrial sectors, including power generation, emergency systems, or marine applications, is uncertain. As a result, the utilization of traditional fuels is not anticipated to be fully phased out in the near future. To address this, new technologies, such as those that employ oxidising atmospheres, have been explored as a means to enhance the pollution control capabilities of existing technologies, as the Exhaust Gas Recirculation (EGR) system. In this regard, the present study has assessed the efficacy of ozone atmosphere exposure in mitigating the formation of undesired fouling deposits within the system, with the aim of facilitating more efficient operation of EGR devices and extending their service life. To this end, dry soot samples have been exposed to various ozone atmospheres at different temperatures and ozone concentrations through the utilization of an experimental test bench. The oxidation potential of these atmospheres has been evaluated through the analysis of the deposit mass loss. Likewise, confocal microscopy techniques have been employed to obtain the 3D topography of the fouling samples before and after the ozone treatment, allowing the assessment of the deposit thickness reduction, as well as the surface roughness variation. Additionally, thermogravimetric analysis has been conducted to examine the effects of the oxidation processes on fouling samples composition. The findings of this study have revealed that ozone atmospheres have been effective in reducing deposit mass at ozone treatment temperatures above 100 °C. The reduction in mass has reached 78.5% and 91.8% with treatment temperature of 140 °C with ozone concentrations of 30 gO3/m³ and 50 gO3/m³, respectively. It has also been established that treatment conditions with ozone concentrations of 30 gO3/m³ and 50 gO3/m³ are effective in reducing the thickness of deposits even at intermediate treatment temperatures, resulting in a thickness reduction of 78.6% and 81.1% at 80 °C, respectively. Additionally, it has been observed that the ozone exposure leads to the increase in the proportion of volatile material within the deposit.

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

The utilization of biodiesel as an alternative partial replacement of diesel fuel was shown to improve exhaust emissions from diesel engines. Waste cooking oil biodiesel (WCO) has also gained more attention due to edible biofuel supply and the environment. In this study, a nonthermal plasma (NTP) technique was applied to be equipped into the after-treatment system of a four-cylinder diesel engine at medium- and high-load conditions. The exhaust gases in the NTP state from the combustion of WCO and diesel (D100) fuels were partially drawn by spectrometers and nanoparticle-number-derived characteristics were analyzed. The particle number, area, and mass concentrations were in log-normal distribution over equivalent diameters, and they were higher at high load. The concentration of the particulate matter (PM) was lower but was larger in size when the NTP charger was activated due to coagulation principally owing to WCO's number and surface area. The total particle masses were lower for WCO at the two load conditions tested. During NTP charger activation, the mass mean diameters were increased by maximum values of 24.0% for D100 and 5.5% for WCO. The PM removal efficiencies were maximized by 10.8% for D100 and 16.7% for WCO when the NTP charger was in use, and the WCO exhaust was dominantly seen to simultaneously reduce NO _x and PM emissions.

Two-stage continuous production process for fatty acid methyl ester from high FFA crude palm oil using rotor-stator hydrocavitation

Two-stage continuous production process for fatty acid methyl ester (FAME) from crude palm oil was performed using the rotor-stator hydrocavitation reactor. The novel ABS filament printed rotor having spherical holes on the surface of the rotor which is an efficient, fast and cost-effective procedure, was installed in the stainless steel stator of hydrosonic reactor. The 3D printed hydrosonic reactor was used to treat the FFA-rich in MCPO by esterification and followed by transesterification to produce the methyl ester. The optimum conditions of both esterification and transesterification processes were determined using the response surface methodology (RSM). For the 1st step esterification, the conditions of methanol 17.7 vol%, sulfuric acid 2.9 vol%, 3000 rpm rotor speed, hole's diameter and depth 4 and 6 mm, and 25 L/h MCPO, were used for decreasing the FFA from 11.456 to 1.028 wt%. For the 2nd step, transesterification was employed with the optimal condition of 28.6 vol% methanol, 6.2 g/L of potassium hydroxide, 3000 rpm rotor speed, the dimension of the spherical holes on the rotor's surface having diameter of 6.4 mm and 6.2 mm in depth, and esterified oil flow rate 25 L/h, for producing the methyl ester to over 99.163 wt%. Moreover, the purified biodiesel yields and the average energy consumption for the entire two-stage continuous process between hydrosonic and ultrasonic clamp reactors were compared. The results of purified methyl ester clearly indicate that the methyl esters of 99.163 wt% and 97.814 wt% were achieved from hydrosonic and ultrasonic clamp reactors, respectively, under the same optimized conditions. The maximum yields of purified biodiesel were 97.51 vol% and 88.69 vol% using hydrosonic and ultrasonic clamp reactors, respectively. The average energy consumption for the entire continuous two-stage process for both hydrosonic and ultrasonic clamp reactors were 0.049 and 0.056 kW h/L, respectively. For practical industrial processes, stainless steel rotors inside the stator was manufactured by CNC machine, which was also verified under the optimum conditions. The results showed that 1.07 wt% FFA and 99.221 wt% methyl ester of were obtained from first step and second step, respectively.