Joint development to check diesel particles

Edited by the Engineeringtalk editorial team Apr 19, 2006

Diesel particulate filter simulation tool to let firms computationally design and optimise particulate filters in car and truck applications with respect to soot loading and regeneration behaviour.

Fluent and J Eberspacher, a German automotive parts manufacturer, are jointly developing a diesel particulate filter simulation tool.

This tool will let companies computationally design and optimise particulate filters in passenger car and truck applications with respect to soot loading and regeneration behaviour for a filter's projected full lifecycle before it is even manufactured.

Increasingly, people in urban landscapes are experiencing deleterious health effects resulting from prolonged exposure to microscopic dust particles, especially particulates coming from the increasing numbers of diesel powered trucks and cars.

The current generation of particulate filters are effective within domestic diesel cars and are good at reducing particulate emissions.

However, a rising demand for improvements in filter designs is being demanded by governmental agencies especially with respect to their regeneration behaviour during normal cyclic operating conditions out on the street.

Parallel to this growing need to improve the increasing number of diesel filters in cities, manufacturers have identified a need for a software prediction tool to assess the behaviour of such filters in the early design phase.

Ideally, they want to take into account the condition of a given car's exhaust, the mileage of the car, its filter size and its filter shape in a flow modelling tool.

Fluent and Eberspacher have generated a combined 3D/1D modelling tool, using the Fluent CFD code and Matlab from Mathworks, to calculate diesel filter soot distribution, pressure and regeneration under any operating condition.

Eberspacher's Matlab based diesel filter tool simulates 1D channels during loading and regeneration and then, because it is closely coupled with Fluent's 3D CFD flow modelling datasets, can simulate a complete diesel filter's behaviour for local particulate buildup and regeneration over time.

This modelling approach can allow for the effects of non-uniform filter inlet flow conditions in a particular car to be simulated thus permitting an assessment of the soot distribution inside.

A custom filter design that prevents damaging soot build up can then be determined in the computer before it is manufactured.

A further requirement to a filter's design that the software tool provides is the ability to predict the local soot oxidation as the filter is exposed to regeneration under different driving conditions.

The filter's loading behaviour after partial regeneration when it has experienced different types of driving cycles is of special interest to manufacturers, and that too can be predicted using the tool.

This diesel filter design tool can simulate both a clean filter as well as a loaded filter after the car experiences high mileage.

In the latter case, effects such as ash deposits (resulting both from oil ash or ash from fuel additives) can be considered.

Gerd Gaiser, Director Pre-Development Exhaust Technology of Eberspacher, said: "The software resulting from this co-operation allows us to design optimum filter geometries with regard to soot loading distributions and the avoidance of partial regenerations even under difficult design conditions".

"The ability to predict the local regeneration behaviour and thereby avoid excessive local temperatures is a major requirement for the design of diesel filters consisting of less expensive but more temperature sensitive material".

Werner Seibert, Global Automotive Segment Manager for Fluent, said: "Our collaboration with Eberspacher has produced a unique design methodology that I believe will transform the design process for complex automotive diesel filters".

"The net effect will be a new tool to improve filter design and thereby reduce particulate emissions at the early design stage which should lead to an improved environment for everyone".