Oxidation Catalytic Converter Research Articles

Effects of fuel injection system and exhaust gas catalytic treatments on PAH emissions from motorcycles.

The motorcycles are unignorable near-ground pollutant emission sources that increase the human exposure in the dense area. However, the information of the polycyclic aromatic hydrocarbons (PAHs) emissions under different scenarios of engine and emission control for motorcycle is limited. This study focused on the PAH emissions from two fuel-injection types of motorcycles, including the premixed fuel-injection (PFi) with carburetor and electronic fuel-injection (EFi). Specifically, the effects of throttle opening (TO), secondary air system (SAS), oxygen sensor (OS), oxidation catalytic converter (OCC), and three-way catalytic converter (TWC) on PAH emissions are investigated. Results show that the PAH emission concentrations increase 227-727%, 351-492%, and 155-408% by the increasing TO ratio, unworking SAS, and OS units in both motorcycles. For the PFi engine, the OCC unit is found to be more effective in PAH control (31-89%) than the SAS system (72-80%), especially under low TO operation. For the EFi engine which dominates the motorcycle market recently, the oxygen sensor for more accurate combustion control shows a better PAH reduction (36-76%) than TWC system (21-66%). The ultra-fine particulate phase PAHs, which is hardly removed by catalyst, needs to be further considered. Moreover, the total PAH emission level of the EFi engine is still about ten times higher than that of the PFi. By the annual emission calculation for three densely populated countries, the recent evolution significantly reduces the annual hydrocarbon (HC), carbon monoxide (CO), and nitrogen oxide (NOx) emissions but have unignorable PAH emissions. These emissions continuously affect the human health in the near-ground urban air and need to be considered in the next generation of motorcycle design.

Research the Effect of Oxidation Catalytic Converter on Reducing Diesel Engine Particulate Emission Based on Artificial Intelligence

Research the Effect of Oxidation Catalytic Converter on Reducing Diesel Engine Particulate Emission Based on Artificial Intelligence

Modeling the Effects of the Inlet Manifold Design on the Performance of a Diesel Oxidation Catalytic Converter

The effect of inlet flow distribution on the performance characteristics of a catalytic converter is analyzed for two common inlet manifold designs. Three-dimensional steady-state computational flu...

VOCs emission characteristics in motorcycle exhaust with different emission control devices

Speciated VOCs and regulated air pollutant emissions (CO, HC and NO) of carburetor (CB) and fuel injection (FI) motorcycles were evaluated based on engine dynamometer tests. Effects of engine loads and emission control systems were evaluated. CB was equipped with oxidation catalytic converter (OCC) and secondary air system (SAS) while FI had three-way catalytic converter (TWC) and oxygen sensor (OS). Under normal operation of the control devices, the emissions of regulated pollutants and the sum of detected VOCs (ΣVOC) were higher in CB than in FI motorcycle. Alkanes and aromatics had the highest concentrations contributing approximately 90% to the ΣVOC while xylene and toluene were most abundant among the BTEX, in both motorcycles. Emissions of all regulated pollutants and ΣVOC increased with increase in engine load. The emission control devices showed differential efficiencies on different VOC groups. Average emission reduction efficiencies of OCC with SAS (CB motorcycle) were 45.4% (ΣVOC) and 48.6% (BTEX) and TWC with OS (FI motorcycle) were 74.4% (ΣVOC) and 88.0% (BTEX). Without SAS, the efficiency of OCC dropped to 30.2% (ΣVOC) and 34.9% (BTEX) in CB motorcycle. Similarly, the efficiency of TWC reduced to 69.0% (ΣVOC) and 85.2% (BTEX) when the OS was blocked in FI motorcycle. The ozone formation potentials of VOCs ranged from 500 mg-O3/m3 (FI motorcycle with TWC and OS, TO 20%) to 2218 mg-O3/m3 (CB motorcycle without control system, TO 30%).

Effects of FAME biodiesel and HVORD on emissions from an older-technology diesel engine.

The results of laboratory evaluations were used to compare the potential of two alternative, biomass-derived fuels as a control strategy to reduce the exposure of underground miners to aerosols and gases emitted by diesel-powered equipment. The effects of fatty acid methyl ester (FAME) biodiesel and hydrotreated vegetable oil renewable diesel (HVORD) on criteria aerosol and gaseous emissions from an older-technology, naturally aspirated, mechanically controlled engine equipped with a diesel oxidation catalytic converter were compared with those of widely used petroleum-derived, ultralow-sulfur diesels (ULSDs). The emissions were characterized for four selected steady-state conditions. When fueled with FAME biodiesel and HVORD, the engine emitted less aerosols by total particulate mass, total carbon mass, elemental carbon mass and total number than when it was fueled with ULSDs. Compared with ULSDs, FAME biodiesel and HVORD produced aerosols that were characterized by single modal distributions, smaller count median diameters, and lower total and peak concentrations. For the majority of test cases, FAME biodiesel and HVORD favorably affected nitric oxide (NO) and adversely affected nitrogen dioxide (NO2) generation. Therefore, the use of these alternative fuels appears to be a viable tool for the underground mining industry to address the issues related to emissions from diesel engines, and to transition toward more universal solutions provided by advanced engines with integrated exhaust after treatment technologies.

Effects of diesel/ethanol dual fuel on emission characteristics in a heavy-duty diesel engine

In order to reduce emissions and diesel consumption, the gas emissions characteris-tics of diesel/aqueous ethanol dual fuel combustion (DFC) were carried out on a heavy-duty turbocharged and intercooled automotive diesel engine. The aqueous ethanol is prepared by a blend of anhydrous ethanol and water in certain volume proportion. In DFC mode, aqueous ethanol is injected into intake port to form homogeneous charge, and then ignited by the diesel fuel. Results show that DFC can reduce NOx emissions but increase HC and CO emissions, and this trend becomes more prominent with the increase of water blending ratio. Increased emissions of HC and CO could be efficiently cleaned by diesel oxidation catalytic converter (DOC), even better than those of diesel fuel. It is also found that DFC mode reduces smoke remarkably, while increases some unconventional emissions such as formaldehyde and acetal-dehyde. However, unconventional emissions could be reduced approximately to the level of baseline engine with a DOC.

Principles for construction of mathematical model of a modern low-toxic diesel engine for transport and technological means and agricultural machines

The article considers the principles of mathematical modeling of thermodynamic and gasdynamic processes in modern diesel engine and in systems intended to reduce the harmful substances level in exhaust gases, namely in oxidation catalytic converter, in particulate filter with regeneration system and in selective catalytic reduction system for nitrogen oxides neutralization.

Simulation of oxidation catalyst converter for after-treatment in diesel engines

In the diesel engine after-treatment system of motor vehicles, Diesel Oxidation Catalytic (DOC) converter is used to purify hydrocarbons (HCs) consisting of oil and fuel residue, and Carbon Monoxide (CO) from the exhaust gas. The exhaust gas flowing through DOC converter experiences chemical reactions that oxidize CO and HCs which are formed by incomplete combustion. Reactive properties, geometric features and thermal properties are fundamental design elements of a DOC converter. Flow of the exhaust gas through the converter with these properties can be described using a mathematical model given by Partial Differential Equations (PDEs). In this work, a simulation program for solving these PDEs describing the mathematical model of DOC converter was developed. PDEs were solved by Finite Volume Method (FVM) for volume elements and an implicit method for time steps. Using the solution of PDEs, reduction of CO and HCs at the outlet of the converter was computed. Thus, our model can be used to simulate, or design DOC converters and to predict the reduction of CO and HCs from DOC converters.

A fleet-prediction oriented catalyst model for highly transient driving in cold and hot mode conditions

Various models for simulating catalytic converters are given in the literature. They deal with a wide range of different aspects. In addition to the type of catalytic converter (three-way catalytic converter, diesel oxidation catalytic converter, etc.), the aspect of complexity versus accuracy and speed can be tackled using different approaches. Moreover, the desired use has an influence on the model structure: optimization of catalyst design or prediction of emissions from real-world traffic situations or optimization of air–fuel ratio control? The model described here has been developed to predict emissions in arbitrary real-world driving patterns, both for hot driving as well as for cold-start situations. As these tests mainly last over 30 minutes (real time), the calculation effort should be small. The model should be easy to parameterize, as it should be applicable to vehicles from traffic. A model with a reduced set of chemical reactions has been developed with a particular focus on the thermal balance for cold-start cycles. Its outputs are the pollutant emissions at the tailpipe if the emissions, exhaust mass flow and temperature from the engine are given. It is applied to three-way catalytic converters. It models the chemical phenomena almost entirely based on oxygen storage and release reactions, which dominate highly transient situations. The model has been validated against a large database of measured driving cycles, carried out using different types of cars. It presents an acceptable degree of correlation between simulated and experimental results.

Effects of a diesel oxidation catalyst on gaseous pollutants and fine particles from an engine operating on diesel and biodiesel

The effects of a diesel oxidation catalytic (DOC) converter on diesel engine emissions were investigated on a diesel bench at various loads for two steady-state speeds using diesel fuel and B20. The DOC was very effective in hydrocarbon (HC) and CO oxidation. Approximately 90%–95% reduction in CO and 36%–70% reduction in HC were realized using the DOC. Special attention was focused on the effects of the DOC on elemental carbon (EC) and organic carbon (OC) fractions in fine particles (PM2.5) emitted from the diesel engine. The carbonaceous compositions of PM2.5 were analyzed by the method of thermal/optical reflectance (TOR). The results showed that total carbon (TC), OC and EC emissions for PM2.5 from diesel fuel were generally reduced by the DOC. For diesel fuel, TC emissions decreased 22%–32% after the DOC depending on operating modes. The decrease in TC was attributed to 35%–97% decrease in OC and 3%–65% decrease in EC emissions. At low load, a significant increase in the OC/EC ratio of PM2.5 was observed after the DOC. The effect of the DOC on the carbonaceous compositions in PM2.5 from B20 showed different trends compared to diesel fuel. At low load, a slight increase in EC emissions and a significant decrease in OC/EC ratio of PM2.5 after DOC were observed for B20.

Strategic environmental assessment application for sustainable transport-related air quality policies: a case study in Hanoi City, Vietnam

Recognition has grown among policy-makers that early in the decision-making process, there is a need for an environmental assessment of the effects of the policy, plan, and program (PPP) and their alternatives. Strategic environmental assessment (SEA) is widely recognized as a supporting tool that systematically integrates environmental aspects into strategic decision-making processes, thereby contributing to sustainable development. In this study, SEA was applied for an integrated assessment of environmental, social, and economic impacts of a wide range of scenarios for transport-related air quality policies to help decision-makers in identifying the most sustainable scenario with the purpose of reducing carbon monoxide (CO) concentrations from transport emissions in Hanoi City, Vietnam. In conducting SEA process, the urban air dispersion model MUAIR was used as a quantitative tool in prediction of CO concentrations. To evaluate the predicted impacts of scenarios, the SEA objectives concerning sustainability and the corresponding sustainable indicators were identified. Based on the likely significant predicted impacts on landscape, biodiversity, and health benefits, mitigation measures were proposed. These included planning in infrastructure development and implementation of public education campaign. The results of predicted and evaluated impacts of scenarios as well as proposed mitigation measures were taken into account for supporting sound decision-making that is consistent with the principles of sustainable development. Considering sustainable impacts of the scenarios, the SEA result clearly indicates that a combination of policy for public transport development and policy for installation of oxidation catalytic converter for motorcycles is the most sustainable scenario for reducing CO concentrations from transport emissions.

Mutagenicity of Diesel Exhaust Particles from an Engine with Differing Exhaust After Treatments

This study was conducted to investigate the effects of engine operating conditions and exhaust aftertreatments on the mutagenicity of diesel particulate matter (DPM) collected directly in an underground mine environment. A number of after-treatment devices are currently used on diesel engines in mines, but it is critical to determine whether reductions in DPM concentrations result in a corresponding decrease in adverse health effects. An eddy-current dynamometer was used to operate naturally aspirated mechanically controlled engine at several steady-state conditions. The samples were collected when the engine was equipped with a standard muffler, a diesel oxidation catalytic converter, two types of uncatalyzed diesel particulate filter systems, and three types of disposable diesel particulate filter elements. Bacterial gene mutation activity of DPM was tested on acetone extracts using the Ames Salmonella assay. The results indicated strong correlation between engine operating conditions and mutagenic activity of DPM. When the engine was fitted with muffler, the mutagenic activity was observed for the samples collected from light-load, but not heavy-load operating conditions. When the engine was equipped with a diesel oxidation catalyst, the samples did not exhibit mutagenic activity for any of four engine operating conditions. Mutagenic activity was observed for the samples collected when the engine was retrofitted with three types of disposable filters and sintered metal diesel particulate filter and operated at light load conditions. However, those filtration systems substantially reduced the concentration-normalized mutagenic activity from the levels observed for the muffler.

Study on DOC Auxiliary DPF Regeneration Method

Diesel oil is injected into upriver vent-pipe of diesel oxidation catalyst(DOC) and mixed with the engine exhaust.The diesel oil is oxidized through the catalytic converter and gives out heat to improve the engine exhaust temperature,thus realizing the regeneration of diesel particulate filter(DPF).The whole system consists of fuel injector,oxidation catalytic converter and particulate filter.The regeneration characteristics of this system are researched on the engine bench,including the attainable temperature of exhaust after oxidation catalytic converter at different simulation vehicle speeds and different injection quantities;the temperature rise characteristics after catalytic converter during regeneration;the back pressure characteristics of particulate filter in regeneration process;and the analysis on the economy and secondary pollution of the regeneration method.The results show that when simulation speed is greater than 60 km/h,injection and regeneration can be carried out.The whole regeneration time is 330 s,the economy of the regeneration method is good,and the secondary pollutants are mainly HC and CO.

Effects of Diesel Exhaust Aftertreatment Devices on Concentrations and Size Distribution of Aerosols in Underground Mine Air

Three types of uncatalyzed diesel particulate filter (DPF) systems, three types of high-temperature disposable filter elements (DFEs), and one diesel oxidation catalytic converter (DOC) were evaluated in underground mine conditions for their effects on the concentrations and size distributions of diesel aerosols. Those effects were compared with the effects of a standard muffler. The experimental work was conducted directly in an underground environment using a unique diesel laboratory developed in an underground experimental mine. The DPF systems reduced total mass of aerosols in the mine air approximately 10-fold for light-load and 20-fold or more for high-load test conditions. The DFEs offered similar reductions in aerosol mass concentrations. The efficiency of the new DFEs significantly increased with accumulation of operating time and buildup of diesel particulate matter in the porous structure of the filter elements. A single laundering process did not exhibit substantial effects on performance of the filter element The effectiveness of DPFs and DFEs in removing aerosols by number was strongly influenced by engine operating mode. The concentrations of nucleation mode aerosols in the mine air were found to be substantially higher for both DPFs and DFEs when the engine was operated at high-load modes than at low-load modes. The effects of the DOC on mass and number concentrations of aerosols in mine air were relatively minor when compared to those of the DPF and DFE systems.

Effect of Diesel/methanol compound combustion on Diesel engine combustion and emissions

This paper introduces a Diesel/methanol compound combustion system (DMCC) and its application to a naturally aspirated Diesel engine with and without an oxidation catalytic converter. In the DMCC system, there are two combustion modes taking place in the Diesel engine, one is diffusion combustion with Diesel fuel and the other is premixed air/methanol mixture ignited by the Diesel fuel. Experiments were conducted on a four cylinder DI Diesel engine, which had been modified to operate in Diesel/methanol compound combustion. Experiments were conducted at idle and at five engine loads at two levels of engine speeds to compare engine emissions from operating on pure Diesel and on operating with DMCC, with and without the oxidation catalytic converter. The experimental results show that the Diesel engine operating with the DMCC method could simultaneously reduce the soot and NOx emissions but increase the HC and CO emissions compared with the original Diesel engine. However, using the DMCC method coupled with an oxidation catalyst, the CO, HC, NOx and soot emissions could all be reduced.

Experimental study on exhaust emissions from a multi-cylinder DME engine operating with EGR and oxidation catalyst

The recent increase in the world oil price and concern with the growing awareness of the environmental problems associated with the use of petroleum fuels, has led to more interests on alternative fuels. DME is found to be one kind of promising clean alternative fuel for diesel engine. Smokeless emission can be realized under all operating conditions. This characteristic provides a potential for a large EGR ratio on the DME engine. Experimental results indicate that NO x emission can be reduced about 40% at a large EGR ratio without visible smoke and deterioration in thermal efficiency of DME engine. However, CO emission increases with the rise of EGR ratio. A commercial oxidation catalytic converter is used to investigate its influence on CO emission. Very promising results with respect to CO emission reduction can be achieved in DME engine. It is obvious that vehicle DME engine can meet more strict emission regulation with an integrated system with EGR and oxidation catalytic after treatment.

Influence of fuel properties, nitrogen oxides, and exhaust treatment by an oxidation catalytic converter on the mutagenicity of diesel engine emissions

Particle emissions of diesel engines (DEP) content polycyclic aromatic hydrocarbons (PAH) these compounds cause a strong mutagenicity of solvent extracts of DEP. We investigated the influence of fuel properties, nitrogen oxides (NO( x )), and an oxidation catalytic converter (OCC) on the mutagenic effects of DEP. The engine was fuelled with common diesel fuel (DF), low-sulphur diesel fuel (LSDF), rapeseed oil methyl ester (RME), and soybean oil methyl ester (SME) and run at five different load modes in two series with and without installation of an OCC in the exhaust pipe. Particles from the cooled and diluted exhaust were sampled onto glass fibre filters and extracted with dichloromethane in a soxhlet apparatus. The mutagenicity of the extracts was tested using the Salmonella typhimurium/mammalian microsome assay with tester strains TA98 and TA100. Without OCC the number of revertant colonies was lower in extracts of LSDF than in extracts of DF. The lowest numbers of revertant colonies were induced by the plant oil derived fuels. In three load modes, operation with the OCC led to a reduction of the mutagenicity. However, direct mutagenic effects under heavy duty conditions (load mode A) were significantly increased for RME (TA98, TA100) and SME (TA98). A consistent but not significant increase in direct mutagenicity was observed for DF and LSDF at load mode A, and for DF at idling (load mode E) when emissions were treated with the OCC. These results raise concern over the use of oxidation catalytic converters with diesel engines. We hypothesise that the OCC increases formation of direct acting mutagens under certain conditions by the reaction of NO( x ) with PAH resulting in the formation of nitrated-PAH. Most of these compounds are powerful direct acting mutagens.

Exhaust-pipe fuel injection for active particulate filter regeneration

Particulate filter systems which meter fuel into the exhaust system offer benefits at many operating points. The injected diesel fuel is catalytically converted in the oxidation catalytic converter. It is vital to have a very responsive system, which enables rapid controllability while the vehicle is in operation. This paper from J. Eberspacher describes a system for injecting fuel into the exhaust system which works without any engine-related measures and which represents the prototype of an independent active regeneration aid for vehicles with diesel particulate filters.

Study on combustion and emission characteristics of a vehicle engine fuelled with dimethyl ether

This paper reports on basic investigations into identifying the optimum parameters of a fuel system for a four-cylinder, direct-injection diesel engine with dimethyl ether (DME) as fuel—such as nozzle opening pressure, nozzle type, etc. Combustion and emission characteristics of the DME engine are studied experimentally. Smokeless emission can be realized under all operating conditions; in addition, NOx, HC, CO and particulate matter (PM) emissions of the CA498 DME engine can meet Euro 3 regulations by using an oxidation catalytic converter. It is also indicated that NO x emissions can reduce by about 40 per cent at larger exhaust gas recirculation ratios with less penalty on the brake thermal e ffi ciency of the DME engine. A DME-powered vehicle has been developed and is operating successfully on the highway. The maximum speed and accelerating performance are equivalent to those of diesel operation; the noise of the vehicle is lower than that of diesel vehicles. Very promising results with respect to emission, e ffi ciency, durability, and combustion noise can be achieved in a DME engine.

Influence of Exhaust Aftertreatment Devices on Heavy-Duty Diesel Engine's Particulate Emissions

This paper describes the impact of two exhaust aftertreatment devices, an oxidation catalytic converter and a diesel particulate Ž lter, on the particulate emissions of a heavy-duty diesel engine, the emphasis being on diesel particulate composition and size distribution. The analysis showed that the catalytic converter did not alter the size distribution signiŽ cantly, except for an increased production of nanosized particles below 30 n miles in mean diameter. On the other hand, the ceramic monolith wall- ow Ž lter reduced the emitted particle number up to 100 times. The results again indicated that a diesel particulate Ž lter can also increase the number of nanosizedparticles. Further investigations, however, revealed that the formation of nanosized particles downstream of the oxidation catalytic converters and diesel particulate Ž lters, respectively, is biased by inadequate sampling conditions.As long as realistic sampling conditions are applied, both catalyst and Ž lter reduce particle emissions over the entire size range.