28 August 2010

The 14th ETH Conference on Combustion Generated Nanoparticles was held August 1-4, 2010 in Zurich. Presenters at this year’s meeting discussed particulate formation fundamentals, vehicle and engine emissions, transformation of particulates in the ambient environment, health effects, particle filter systems, instrumentation, legislation and particles from combustion sources other than vehicle engines. The meeting also included a poster session with 56 posters. This year the conference hit a new attendance record with over 440 registered delegates.

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The conference kicked off with a key-note lecture by Matti Maricq of Ford Research, USA on particle free combustion. While “particle free combustion” technology currently exists in the form of the port fuel injected gasoline engine, the fuel efficiency from this engine is inferior to that of the diesel engine and it is not adequate for meeting many national and international CO2 emissions targets. However, technologies applicable to diesel engine providing “particle free combustion” are not without their own challenges:

  • Low temperature combustion strategies need to overcome higher noise and higher CO and HC emissions.
  • Extended lift-off combustion requires improvements in control strategies to deal with sensitivity to temperature, pressure, and fuel quality.
  • Reactivity controlled compression ignition (dual fuel strategies using gasoline and diesel fuel) must overcome the drawback of increased complexity.
  • HCCI and PCCI perform well, but have limited ranges of operation.
  • Biofuels have tradeoffs with respect to fuel system durability and lower energy density.

Light-Duty Particle Number Emissions. With increased attention being paid to particle number emissions by regulators in Europe and now in California, the question of how to deal with direct injection gasoline (GDI) engines is often raised. Some insight into the effect of the proposed CARB LEV III regulation on GDI technology was provided by a recent study by Southwest Research Institute [Khalek] where particle mass and number emissions were characterized from a 2009 vehicle with a GDI engine. The study tested a range of commercially available US gasoline fuels with different volatility and aromatic content. The GDI engine met the proposed CARB LEV III particle mass limit for 2014 with all fuels but not the proposed 2017 limit with low volatility/high aromatic fuel. The challenge was even more substantial with respect to particle number emissions. The GDI engine met the proposed 2014 number limit with two out of three fuels but was unable to meet the proposed 2017 limit with any of the fuels.

In related developments in Europe, particle number emissions from light-duty Euro 6 positive ignition (e.g., gasoline) engines will be regulated with a limit being defined as early as the end of 2011. The limit will take into account actual particle number emissions, available techniques for emission reduction and related costs [Steininger, European Commission].

Ford Germany [Vogt] measured particle number emissions from a number of Euro 5 and 6 light duty diesel vehicles in order to quantify the precision of the PMP test procedure. They found particle number differences of >100% between tests on the same vehicle that originated primarily with the vehicle and not the instrumentation. An inter-lab uncertainty of <27% was estimated for the particle number method.

Development of a new light duty test cycle by the World Light duty Test Procedure (WLTP) group for a future global technical regulation (GTR) under the 1998 UNECE agreement that aims to harmonize the related measurement procedures offers an opportunity to revise the particle number measurement procedures [Steininger, European Commission].

The conference also included a number of other interesting presentations. A full program and presentation abstracts is available from the conference website. The next year meeting, 15th ETH Conference on Combustion Generated Nanoparticles, will be held on 26-29 June, 2011.

Conference website: www.lav.ethz.ch/nanoparticle_conf