Andreas Janssen

Tailor-made fuels from biomass — potential of biogenic fuels for reducing emissions

Fuels made from biomass offer an enormous potential for use in vehicle applications by greatly reducing carbon dioxide emissions affecting the climate as well as engine pollutant emissions such as soot or nitrogen oxides. Scientists in the Cluster of Excellence “Tailor-made Fuels from Biomass” are researching production as well as the engine’s combustion of innovative biofuels. The long-term objective is to optimize the entire process chain from producing the biomass down to the engine’s combustion without competing with the food chain to the extent possible. Initial fuels with adapted properties confirm the potential of a nearly soot-free combustion in diesel engines.

Surrogate fuels for the simulation of diesel engine combustion of novel biofuels

Recently, several promising biomass-derived fuels for diesel engines have been identified, produced, and tested. Diesel engine experiments confirmed very low soot and low nitrogen oxide emissions. With regard to further improvements of the combustion system, it is desirable to complement the diesel engine experiments with numerical simulations. To date, this is hindered by the lack of suitable chemical reaction mechanisms for these novel fuels. Therefore, a surrogate approach is presented here and applied in computational fluid dynamics simulations. Combustion and pollutant formation is simulated using the representative interactive flamelet model. Ignition, combustion, and pollutant formation are described in a consistent manner by inclusion of detailed reaction chemistry. Different mixtures of n-heptane, toluene, ethanol, dimethylether, ethane, and phenol are employed to describe the combustion chemistry of the biofuels. The compositions of the surrogate fuels are compiled according to hydrogen/carbon ratio, oxygen content, cetane rating, and molecular properties of the experimental fuels. Spray, injection, and evaporation properties of the experimental fuels, as obtained from spray vessel experiments, are included in the computational fluid dynamics simulations. By systematic comparison of experimental and numerical results, the surrogate methodology is validated and an improved understanding of the limitations of the current surrogates is achieved. Thus, a methodology for the fast adoption of novel fuels for simulations is proposed that can be used regardless of the availability of specific chemical reaction mechanisms.

Massgeschneiderte Kraftstoffe aus Biomasse - Potenzial biogener Kraftstoffe zur Emissionsreduktion

Fur den Einsatz in mobilen Anwendungen eroffnen aus Biomasse gewonnene Kraftstoffe ein erhebliches Potenzial, neben einer Reduktion der klimawirksamen Kohlendioxid-Emissionen auch die motorischen Schadstoff-Emissionen wie Rus oder Stickoxide deutlich zu verringern. Wissenschaftler im Exzellenzcluster „Masgeschneiderte Kraftstoffe aus Biomasse“ erforschen die Herstellung sowie die motorische Verbrennung neuartiger Biokraftstoffe. Das langfristige Ziel ist die Optimierung der gesamten Prozesskette von der Biomasse bis hin zum Verbrennungsmotor, moglichst ohne dabei mit der Nahrungsmittelkette zu konkurrieren. Erste Kraftstoffe mit angepassten Eigenschaften belegen das Potenzial einer nahezu rusfreien Verbrennung im Dieselmotor.