Search Results

The increasing use of gasoline direct injection (GDI) engines coupled with the implementation of new particulate matter (PM) and particle number (PN) emissions regulations requires new emissions control strategies. Gasoline particulate filters (GPFs) present one approach to reduce particle emissions. Although primarily composed of combustible material which may be removed through oxidation, particle also contains incombustible components or ash. Over the service life of the filter the accumulation of ash causes an increase in exhaust backpressure, and limits the useful life of the GPF. This study utilized an accelerated aging system to generate elevated ash levels by injecting lubricant oil with the gasoline fuel into a burner system. GPFs were aged to a series of levels representing filter life up to 150,000 miles (240,000 km). The impact of ash on the filter pressure drop and on its sensitivity to soot accumulation was investigated at specific ash levels.

Measurements of particulate matter (PM) from spark ignition (SI) engine exhaust using dilution tunnels will become more prevalent as emission standards are tightened. Hence, a study of the dilution process was undertaken in order to understand how various dilution related parameters affect the accuracy with which PM sizes and concentrations can be determined. A SI and a compression ignition (CI) engine were separately used to examine parameters of the dilution process; the present work discusses the results in the context of SI exhaust dilution. A Scanning Mobility Particle Sizer (SMPS) was used to measure the size distribution, number density, and volume fraction of PM. Temperature measurements in the exhaust pipe and dilution tunnel reveal the degree of mixing between exhaust and dilution air, the effect of flowrate on heat transfer from undiluted and diluted exhaust to the environment, and the minimum permissible dilution ratio for a maximum sample temperature of 52°C.

Recently, it was reported that the atmospheric pollution levels of nitrogen dioxide (NO2) and particulate matter (PM) are not decreasing despite the introduction of stricter vehicle emission regulations. The difference between conditions of the test cycles defined by the vehicle emission regulations and the real driving can contribute to the differences between expected and actual pollution levels. This has led to the introduction of in-use vehicle emission monitoring and regulations by means of a portable emission measurement system (PEMS). An optimized on-board PM analyzer was developed in this study. The on-board PM analyzer is a combination of a partial flow dilution system (PFDS) particulate sampler and a diffusion charger sensor (DCS) for real-time PM signals. The measuring technology and basic performance of the analyzer will be explained. Acceleration of the vehicle can cause uncertainty of flow measurement in the PM sampler.

Fine particle emissions from engine exhaust have attracted attention because of concern of their higher deposition fraction in alveoli. Since it was observed that sizes of solid particles in exhaust of conventional internal combustion engine technologies are mainly distributed above 30 nm and the mainly irreproducible sensitivity to volatile particles can be reduced, the current solid particle number (PN) measurement methodology was targeted to PN emissions particles larger than 23 nm. The necessity of the measurement of particles smaller than 23 nm is now under discussion. It is also surmised that there is difference between emissions under regulatory defined test cycles and real driving conditions. Currently, implementation of further real driving emission regulations utilizing portable emissions measurement systems (PEMS) is in place for the EU and being actively discussed in other regions.

Automobile Particulate Matter (PM) Emission regulation requires gravimetric determination of PM collected on filter media under simulated driving conditions in the laboratory traditionally in a full flow Constant Volume Sampling (CVS) dilution tunnel. There have been discussions about whether current sampling and measurement practices are sufficiently accurate in quantifying PM at the upcoming 1mg/mi PM emissions standards of CARB LEV III. Sampling technique alternative to a CVS such as a Partial Flow Dilution (PFD) system has already been developed and is acceptable for certification testing. Lower dilution ratios and higher filter face velocity (FFV) are options to load traceable amount of PM on filter in case of light duty vehicle (LDV) testing. On the other hand higher dilution ratios and lower FFV are required for heavy duty engine (HDE) testing to keep the PM loaded on filter <400μg.

Currently, states that are out of compliance with the National Ambient Air Quality Standards must, according to the Clean Air Act Amendments of 1990 (CAAA), develop and implement control strategies that demonstrate specific degrees of reduction in emissions-with the degree of reduction depending upon the severity of the problem. One tool that has been developed to aid regulators in both deciding an appropriate course of action and to demonstrate the desired reductions in mobile emissions is EPA's Mobile 5a emission estimation model. In our study, Mobile 5a has been used to examine the effects of regulatory strategies, as applied to the Northeast United States, on vehicle emissions under worst-case ozone-forming conditions.

The Particle Measurement Programme (PMP) established under the United Nations Economic Commission for Europe has developed the solid particle number (PN) measurement methodology, which has relatively higher sensitivity than the particulate matter measurement protocol. The first PN emission regulation was introduced in 2011. The stationary PN measurement system (PMP system) has been applied in the chassis and the engine test cells. In recent years, real driving emissions (RDE) measurement is attracting attention. Portable emissions measurement systems for PN measurement (PN-PEMS) which can be installed on vehicles during RDE testing are available now. The European RDE regulation requires validation of PN-PEMS by comparing emission measurement results with a stationary PMP system on a chassis dynamometer prior to the on-road emissions testing. Measurement differences between the PN-PEMS and the PMP system has to be within the tolerance defined by the regulation.

The Wankel rotary engine is more compact than conventional piston engines, but its oil and fuel consumption must be reduced to satisfy emission standards and customer expectations. A key step toward this goal is to develop a better understanding of the apex seal lubrication to reduce oil injection while reducing friction and maintaining adequate wear. This paper presents an apex seal dynamics model capable of estimating relative wear and predicting friction, by modeling the gas and oil flows at the seal interfaces with the rotor housing and groove flanks. Model predictions show that a thin oil film can reduce wear and friction, but to a limited extent as the apex seal running face profile is sharp due to the engine kinematics.

The particle number (PN) emission regulation has been implemented since 2011 in Europe. PN measurement procedure defined in ECE regulation No. 83 requires detecting only solid particles by eliminating volatile particles, the concentrations of which are highly influenced by dilution conditions, using a volatile particle remover (VPR). To measure PN concentration after the VPR, a particle number counter (PNC) which has detection threshold at a particle size of 23 nm is used, because most solid particles generated by automotive engines are considered to be larger than 23 nm. On the other hand, several studies have reported the existence of solid and volatile particles smaller than 23 nm in engine exhaust. This paper describes investigation into a measurement method for ultrafine PNCs with thresholds of below 23 nm and evaluation of the VPR performance for the particles in this size range. The detection efficiency of an ultrafine PNC was verified by following the ECE regulation procedure.

A Particle Number (PN) limit for Gasoline Direct Injection (GDI) vehicles was introduced in Europe from September 2014 (Euro 6b). In addition, further certification to Real Driving Emissions (RDE) is planned [1] [2], which requires low and stable emissions in a wide range of engine operation, which must be durable for at least 160,000 km. To achieve such stringent targets, a ceramic wall-flow Gasoline Particulate Filter (GPF) is one potential emission control device. This paper focuses on a catalyzed GPF, combining particle trapping and catalytic conversion into a single device. The main parameters to be considered when introducing this technology are filtration efficiency, pressure drop and catalytic conversion. This paper portrays a detailed study starting from the choice of material recipe, design optimization, engine bench evaluation, and final validation inside a standard vehicle from the market during an extensive field test up to 160,000 km on public roads.

Three-piece oil control rings (TPOCR) are widely used in the majority of modern gasoline engines and they are critical for lubricant regulation and friction reduction. Despite their omnipresence, the TPOCRs’ motion and sealing mechanisms are not well studied. With stricter emission standards, gasoline engines are required to maintain lower oil consumption limits, since particulate emissions are strongly correlated with lubricant oil emissions. This piqued our interest in building a numerical model coupling TPOCR dynamics and oil transport to explain the physical mechanisms. In this work, a 2D dynamics model of all three pieces of the ring is built as the main frame. Oil transport in different zones are coupled into the dynamics model. Specifically, two mass-conserved fluid sub-models predict the oil movement between rail liner interface and rail groove clearance to capture the potential oil leakage through TPOCR. The model is applied on a 2D laser induced fluorescence (2D-LIF) engine.

The LDV gasoline emission regulation is set to be tightened for Euro7. In particular, the particulate number (PN) requirement has been significantly tightened requiring a GPF with extra - high filtration efficiency to meet the target requirement. In order to meet the stricter PN requirements, GPF substrate material improvement is necessary. However, conventional GPF material improvement for high filtration efficiency will increase the filter backpressure significantly. The relationship between pressure drop and CO2 emission is difficult to quantify but high pressure drop can potentially increase the CO2 emission. Therefore, Membrane Technology (MT) is the key to break through the trade-off between filtration performance and pressure drop. MT is thin and dense layer of small grains applied on the GPF surface. MT application can increase particulate filtration efficiency significantly with minimal pressure drop increase.

Diesel Particulate Filters (DPF) are becoming mandatory for many Heavy Duty Vehicle (HDV) and Non Road Mobile Machinery (NRMM) applications as the requirement for particulate filtration performance has increased over this past decade. In a previous study, a new generation of cordierite DPF was developed to meet the latest major emission regulations; PN-PEMS requirement for EuroVI StepE, while maintaining a lower pressure drop and high ash capacity. Despite the improvements made in the latest generation DPF material, the introduction of tighter particulate regulations demands further improvement in DPF technology. More specifically, PN emission limits for Euro7 under wide operation conditions in conjunction with PN down to 10nm, as described in the proposal from Consortium for Ultra Low Vehicle Emission (CLOVE), requires further improvement in PN filtration performance. Pressure drop, which may negatively influence the CO2 emissions, remains a key performance criteria.