Characteristic Fuel Numbers Biofuels II

Authors

Oguz Budak, Prof. Dr.-Ing. Stefan Pischinger, Institute for Combustion Engines (VKA), RWTH Aachen University, Aachen;
Prof. Dr.-Ing. Karl Alexander Heufer, Physico-Chemical Fundamentals of Combustion (PCFC), RWTH Aachen University;
Jörg Dedl, Dr.-Ing. Josef Graf, Prof. Dr.-Ing. Bernhard Geringer,
Institute for Powertrains and Automotive Technology (IFA), TU Vienna;
Dr.-Ing. Ulrich Kramer, Ford-Werke GmbH, Cologne

Summary

The goal of this FVV project is to determine a characteristic number that serves to rate the influence of the fuel on pre-ignition. A distinction is made here between autoignition on a hot surface (glow ignition) and auto-ignition caused by a critical gas phase. With regard to surface-induced pre-ignition (glow ignition), comprehensive analyses have illustrated that flow conditions and thermodynamic operating conditions have a significant influence on glow ignition behavior. Accordingly, none of the test procedures examined does provide a reliable basis for predicting fuel behavior. However, it was possible to identify the influence of hydrocarbons on the glow ignition tendency of a fuel. Based on an adapted CFR engine, it is possible to predict the pre-ignition tendencies of the examined fuels from the gas phase with an accuracy of more than 90 %. An alternative measuring procedure was identified in the Advanced Fuel Ignition Delay Analyser (AFIDA), which made it possible to determine the pre-ignition tendency from the gas phase with an accuracy of over 80 %.

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