Evolution of deep-bed filtration of engine exhaust particulates with trapped mass

Viswanathan, Sandeep; Rothamer, David; Foster, David E.; Fansler, Todd D.; Zelenyuk, Alla; Stewart, Mark; Bell, David M.

doi:10.1177/1468087416675094

Cited by 16 publications

(13 citation statements)

References 63 publications

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“…ρ soot,eff describes the density of an ideal spherical particle with the mobility diameter as particle size. In this work, ρ soot,eff is assumed constant at 800 kg/m 3 because, for particles of relevant size, the density does not have a strong dependency on the diameter …”

Section: Methodsmentioning

confidence: 99%

Extended Model for Filtration in Gasoline Particulate Filters under Practical Driving Conditions

Walter

Neumann

Hinrichsen

2020

Environ. Sci. Technol.

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In order to reliably predict the particle number filtration of gasoline particulate filters (GPF) under practical driving conditions, an extension to established filtration models is developed. For the validation of this approach and in order to close a gap of available measurement data at high space velocity in the literature, the particle-size-resolved fresh filtration efficiency of seven different cordierite filters is determined experimentally. Moreover, the experiments on a dynamic engine test bench focus on the impact of the pore-size distribution and the filter wall thickness under steady-state as well as transient, cold-start conditions. In order to model all trends observed, a new correlation for the particle collection due to inertial deposition is proposed and embedded in a heterogeneous multiscale model framework for a GPF. The presented approach can predict all trends observed in the measurements, including a stabilization of the filtration efficiency with increasing space velocities above a certain level. A comparison of several modeling approaches reveals the partly different behaviors at varying space velocities for the here presented model as well as for established filtration models.

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Section: Methodsmentioning

confidence: 99%

Extended Model for Filtration in Gasoline Particulate Filters under Practical Driving Conditions

Walter

Neumann

Hinrichsen

2020

Environ. Sci. Technol.

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“…More information on the methods used to obtain the mass-mobility relation is given in previous works. 55–57…”

Section: Experimental Methodsmentioning

confidence: 99%

Impacts of combustion phasing, load, and speed on soot formation in spark-ignition engines

Hageman

Rothamer

2019

International Journal of Engine Research

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The premixed prevaporized engine operation method was used to study the effects of main combustion thermodynamic properties and residence time on soot formation in a spark-ignition engine. Select cases were repeated under early-injection, nearly homogeneous, spark-ignition direct-injection operation to determine if the impact of the investigated parameters was the same or if the impact of in-cylinder liquid fuel injection and the resulting heterogeneous fuel-air mixture alters the trends. The original premixed prevaporized study hypothesized that soot is more likely to form after main combustion than during the main combustion event under completely homogeneous conditions. This hypothesis was tested in this study by performing premixed prevaporized combustion phasing sweeps at equivalence ratios (Φs) of 1.35 and 1.40. Both sweeps showed low sensitivity of the particle size distribution to significant changes in peak temperature and pressure during combustion, providing supporting evidence for the original hypothesis. This information was then used to design experiments to isolate the impacts of pressure (engine load) and residence time (engine speed). A premixed prevaporized load sweep showed that particulate emissions increase as a function of load/pressure. A spark-ignition direct-injection load variation showed similar pressure dependence for cases with in-homogeneous in-cylinder fuel-air distributions. A premixed prevaporized residence time variation (performed by changing engine speed) demonstrated an increase in soot formation with increased residence time. The results for identical spark-ignition direct-injection residence-time variations suggest a trade-off in soot formation between the effects of increased mixing time and increased residence time for spark-ignition direct-injection operation. The premixed prevaporized load and speed points were each investigated using Φ sweeps to determine the critical enrichment threshold for soot formation (ΦC) and the dependence of soot formation for Φ > ΦC. The spark-ignition direct-injection investigations were performed at Φ = 0.98, such that any soot formation above the non-fuel-related baseline particle size distribution could be attributed either to mixture heterogeneity or in-cylinder fuel films.

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“…48 Many research works have focused on understanding the gradual bridging of the pores close to the wall surface with deposit and the transition from deep-bed to cake filtration. 38,39,49–53…”

Section: Modellingmentioning

confidence: 99%

Filtration efficiency and pressure drop modelling of particulate filters with rear plug damage

Haralampous

Μαστρόκαλος

Tzorbatzoglou

2020

International Journal of Engine Research

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A model suitable for wall-flow particulate filters with partial rear plug damage is developed and experimentally validated in this work. A ceramic filter with 16% of the rear plugs mechanically removed is tested at steady-state conditions on the engine bench and transient driving cycle conditions on the chassis dynamometer. After decanning of the monolith, destructive analysis is conducted to identify deposit loading variations and scanning electron microscopy is used to study the deposit structures in the channels. It is shown that channels without rear plugs develop distinct deposit structures in the entry zone. Hence, a local pressure loss coefficient is applied to model the effect of entrance flow constrictions, taking also into account deposit restructuring phenomena at higher flow rates. In addition, a deep-bed filtration submodel is used to capture the effect of non-uniform wall velocities on deposit accumulation in the wall. The modified model is first fitted to the engine bench data and then validated in a wider range of conditions using the driving cycle tests. With the exception of prolonged steady-state loading conditions, good pressure drop and filtration efficiency predictions are obtained throughout the tests in conjunction with correct deposit property profiles. Notably, the cold-start worldwide harmonized light vehicles test cycle shows that the current European on-board diagnosis threshold limit for particulate mass is too relaxed to trigger a malfunction indication for moderate filter faults. In conclusion, the model can be applied in damaged particulate filter studies for the assessment of leaked particulate mass, the specification of more effective legislation limits and the development of rigorous on-board diagnosis systems and algorithms.

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Evolution of deep-bed filtration of engine exhaust particulates with trapped mass

Cited by 16 publications

References 63 publications

Extended Model for Filtration in Gasoline Particulate Filters under Practical Driving Conditions

Extended Model for Filtration in Gasoline Particulate Filters under Practical Driving Conditions

Impacts of combustion phasing, load, and speed on soot formation in spark-ignition engines

Filtration efficiency and pressure drop modelling of particulate filters with rear plug damage

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