Engine Exhaust Treatment Research Articles

Spike Electrode-Based DBD Reactor for Improved Electric Discharge Power Toward Better Diesel Engine Exhaust Treatment at Low Applied Voltage

Spike Electrode-Based DBD Reactor for Improved Electric Discharge Power Toward Better Diesel Engine Exhaust Treatment at Low Applied Voltage

Ultrasound-Assisted Deposition of Co-CeO2 onto Ceramic Microfibers to Conform Catalytic Papers: Their Application in Engine Exhaust Treatment.

The combination of the selective catalytic reduction technology with catalytic filters constitutes one of the most efficient ways for diesel engine exhaust treatment. In this paper, the development of catalytic ceramic papers as structured systems for the abatement of diesel soot particles is addressed. Ceramic papers were prepared by the dual-polyelectrolyte papermaking method, which is based on the conventional papermaking technique used for cellulosic papers, in which a portion of cellulosic fibers is replaced by ceramic ones. The deposition of Co and Ce as catalytic materials by the wet spray method on ceramic papers was studied for the development of structured catalysts using an ultrasonic nebulizer and different solvents. The use of alcohol–water solutions for the impregnation of cobalt generated smaller particles and a high dispersion of them on the ceramic fibers, greater than that obtained when pure water was employed. Temperature programmed oxidation (TPO) assays showed that the best catalytic performance was acquired with the catalysts generated with alcohol solvents, showing a maximum rate for soot combustion at a temperature close to 400 °C. The adequate soot combustion performance and the high thermal and catalytic stability make catalytic ceramic papers impregnated by the wet spray method, promising systems for their application as diesel particulate filters.

Catalytic oxidation of NO to NO2 for nitric acid production over a Pt/Al2O3 catalyst

The oxidation of nitric oxide (NO) to nitrogen dioxide (NO2) is a key step both in NOx abatement technologies as well as in the Ostwald process for nitric acid production. A 1 wt.% Pt/Al2O3 catalyst was used to study oxidation of nitric oxide at two different concentrations of NO; 400 ppm NO (representative of engine exhaust treatment) and 10% NO (nitric acid plant). The catalyst was characterised using N2 adsorption and CO chemisorption. The effect of temperature and feed concentration on catalytic activity was investigated.For a feed comprising of 10% NO and 6% O2, Pt/Al2O3 exhibits significant catalytic activity above 300 °C. Addition of 15% H2O in the feed had an insignificant effect on activity of the catalyst. We report for the first time the kinetics for oxidation of NO to NO2 under nitric acid plant conditions. An apparent activation energy of 33 kJ/mol was observed. The rate equation for the overall reaction was determined to be r=kfKG(PO2)0.5, where kf is the forward rate constant. The reaction is independent of NO concentration while it has half order dependency on oxygen. The reaction mechanism which fits our experimental observation consists of dissociative adsorption of oxygen, associative adsorption of nitric oxide with desorption of nitrogen dioxide as the rate limiting step.

A comparative study of oxygenated additives for diesel in compression ignition engine

Performance improvement and emissions control are quite difficult to handle simultaneously in diesel engines. These two tasks can be achieved by one of the methods such as: engine design improvement, engine exhaust treatment and modification in fuel. The modification of fuel using additives is most feasible approach to control the high emissions without deteriorating the engine performance. The aim of this paper is to present the comprehensive review and comparative study of oxygenated additives with respect to engine performance and emission characteristics. It is concluded from literature review that oxygenated compounds are the most suitable and economical among all additives available for this purpose.

Installation of Road Heavy Duty (truck) Engines on Board of Small Inland Self-propelled Barges for an Environmentally Friendly European Inland Waterway Transport of Goods

Freight transport is an essential issue to the competitiveness of territories but the negative impact that it induces, like polluting emissions and their physical consequences on public health, have received growing attention in recent years. Policy makers set goals for sustainable development transportation. Since 1 January 2014, all new trucks have to be powered with a Euro 6 certified engine. Inland waterways are used for transportation of goods and are recognized for their contribution towards sustainable development therefore, engine's barges are old and emission of air pollutants are significant. Currently, the emission limits for inland waterway barges are defined in the Directive 97/86/CE on non-road mobile machinery. That emission limits are similar to Euro 2. The Euro 6 regulations reduced significantly the emission limits. The European Commission has recently proposed a revision of the Directive 97/86/CE which will significantly reduce emission limits. Development of new engines for the small market of small barges in France and also in Europe will be very expensive. Small barges owners should not be able to afford investments in new engines. The range of road engine power is similar to the small barges one. Using Euro 6 heavy duty engines will permit to reach low emissions of air pollutants and should be less expensive for small barges owners. A technical feasibility study had been carried out. It was based on an approach of all parameters of the re-power existing barges. Stakeholder's interviews permitted to deepen same specific topics. The technical feasibility study, added with expected environmental effect, has shown that no technical impossibility had been identified, but some key technical issues have to be considered. It has also confirmed re-powering existing barges (same propulsion power value, no change in naval transmission, etc.) with Euro 6 truck engines is interesting to limit significantly emission air pollutants. The on-board diagnostic controls monitor the engine's exhaust treatment and, it's important to adapt this monitoring for engines used in barges.

Study of Pulsed Plasma in a Crossed Flow Dielectric Barrier Discharge Reactor for Improvement of NOx Removal in Raw Diesel Engine Exhaust

Improved performance of plasma in raw engine exhaust treatment is reported. A new type of reactor referred to as of cross-flow dielectric barrier discharge (DBD) was used, in which the gas flow is perpendicular to the corona electrode. In raw exhaust environment, the cross-flow (radial-flow) reactor exhibits a superior performance with regard to NOX removal when compared to that with axial flow of gas. Experiments were conducted at different flow rates ranging from 2 L/min to 25 L/min. The plasma assisted barrier discharge reactor has shown encouraging results in NOX removal at high flow rates.

Enhanced Performance of Discharge Plasma in Raw Engine Exhaust Treatment-Operation under Different Temperatures and Loads

This paper reports improved performance of discharge plasma in raw engine exhaust treatment. For the purpose of investigation, both filtered and raw diesel engine exhaust were separately treated by the discharge plasma. In raw exhaust environment, the discharge plasma exhibits a superior performance with regard to NOx removal, energy consumption and formation of by-products. In this study, experiments were conducted at conditions of different temperatures and loads.

Unfiltered Diesel Engine Exhaust Treatment by Discharge Plasma: Effect of Soot Oxidation

A cascaded system of electrical discharges (Non-thermal plasma), catalyst and adsorption process was investigated for the removal of oxides of nitrogen (NOx) and carbon monoxide (CO) from a Diesel engine raw exhaust. The three processes were separately studied first, and then the cascaded processes, namely plasma-catalyst and plasma-adsorbent, were investigated. In this paper main emphasis was laid on the effect of carbonaceous soot oxidation on the plasma treatment process. While the cascaded plasma-catalyst process exhibits a higher CO removal, the cascaded plasma-adsorbent process exhibits a higher NOx removal. The experiments were conducted under no-load. The plasma and adsorbent reactors were kept at room temperature throughout the experiment while the catalyst reactor was kept at 200°C/300°C.

Pulsed electrical discharges assisted by dielectric pellets/catalysts for diesel engine exhaust treatment

This paper reports the study on gaseous pollutants (NOx, CO and HCs) using a combination of electric discharge plasma and catalysts. In this study, catalysts being used in conventional catalytic converters of gasoline engine were tried, for the first time, in diesel engine exhaust treatment assisted by electric discharge plasma. Initial studies investigate the effect of packed dielectric materials and catalysts on NOx removal. Both conventional and non-conventional catalysts were used in the studies. With plasma alone, the removal efficiency of oxides of nitrogen was around 75% and with a suitable combination of catalytic reactor the removal efficiency was as high as 90%. Among the catalysts studied, a new catalyst (CuMnAlO/sub 4/) was found to be as effective as the conventional expensive catalyst. The formation of byproducts like N/sub 2/O and HNO/sub 3/ have been studied and the results are discussed.

Diesel engine exhaust treatment with a pulsed streamer corona reactor equipped with reticulated vitreous carbon electrodes

Reticulated vitreous carbon (RVC) has been shown to be useful for high-voltage and ground electrodes in gas-phase pulsed streamer corona reactors. RVC disks with large macroscopic porosity are placed perpendicular to the gas flow and the main axis of a cylindrical corona reactor. This electrode geometry produces streamers that propagate in the direction of the gas flow and are uniformly distributed in the cross section of the reactor. This highly electrically conductive material has large macroscopic porosity, thus allowing for gas flow through the electrodes with low pressure drop. Previous work has considered the effects of RVC electrodes on NO/NO/sub x/ removal from various test gases containing air, water vapor, and ethylene. The present studies show removal of NO/NO/sub x/ from the exhaust of a 5 kW diesel engine. Under cold reactor operating conditions (12/spl deg/C) 81% NO and 53% NO/sub x/ could be removed at an energy yield of 4.8 g/kWh (based on NO). Furthermore, experiments with the combination of TiO/sub 2/ or /spl gamma/-Al/sub 2/O/sub 3/ catalyst particles placed in the region between the high-voltage and ground electrode disks gave NO removal at energy yields of 29 g/kWh and 9 g/kWh, respectively, at about 100/spl deg/C, and significant fractions of the nitrogen were recovered as NO/sub 3//sup -/ deposited on the catalyst surface. The RVC electrode system without catalysts was found to lead to efficient ozone production (55-70 g/kWh) in dry air at room temperature.