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The paper gives a short introduction to the notion of flex fuel approach for diesel engines. The paper continues with a description of a basic study of the diesel combustion process to allow the design of a strategy for recognition of a random bio-diesel fraction, Bx, by a purely software-based sensing technique, which creates an image of the temporal combustion behavior and uses only sensors already in service for current common rail mixture preparation systems. A description is made of two different approaches to software- based sensing techniques, one based on the presence of a crank angle speed sensor and the other on the presence of a lambda sensor in the exhaust system. The principles of the associated software flow diagrams embedded in the engine control unit are also explained. The paper concludes presenting a series of experimental verification data obtained on a large-scale series produced 1.3 liter turbo-charged common rail passenger car engine.

The paper gives a short introduction to the bio-diesel mixture approach for diesel engines. The paper continues with a description of the design of a strategy for recognition of a random bio-diesel fraction, Bx, by a purely software-based sensing technique, which creates an image of the temporal combustion behavior and uses only sensors already in service for current common rail mixture preparation systems. A short description is made of a baseline approach of a sensing technique using a crank angle speed sensor. Hereafter the paper continues by the introduction of several integral or Upper Level (UL) key-parameters applied to enhance the precision of the Bx-detection or completely replace the original lower level combustion key-parameter set, which relates the instantaneous fraction of bio-diesel, Bx, to the engine torque. The paper concludes presenting a series of experimental verification data obtained on a large-scale series produced 1.3 liter Turbo CR-rail passenger car engine.

The success obtained by use of Virtual Engine Modeling (VEM) in the design and development areas of fuel injectors generated a lot of interest from production and quality engineers to possess a similar tool related to spray vessel measurements. To respond to stringent PL6/EURO5 requirements it was decided to develop a Virtual Spray Vessel (VSV) tool capable of predicting spray patterns and perform droplet diameter analysis comparable to real-time Phase Doppler Analysis (PDA) results. The paper describes the analogies between VEM and VSV modeling and the specific new numerical approaches to obtain spatial spray data comparable to conventional mechanical measurement techniques and to perform droplet diameter analysis comparable to PDA data. The paper concludes with a series of comparisons of simulated and experimental data from virtual and real-time measurement vessels.