Technical Sessions

Mr. Dennis Backofen, Otto-von-Guericke University, Institute of Mobile Systems, Chair of Reciprocating Machines, Germany
Dipl.-Chem. Michael Könnig, Otto-von-Guericke-University Magdeburg; Institute of Fluid Dynamics and Thermodynamics; Chair Thermodynamics, Germany
Prof. Dr.-Ing. Dr. h. c. Helmut Tschöke, Otto-von-Guericke-University Magdeburg; Institute of Mobile Systems; Chair Reciprocating Machines, Germany
Prof. Dr.-Ing. Jürgen Schmidt, Otto-von-Guericke-University Magdeburg; Institute of Fluid Dynamics and Thermodynamics; Chair Thermodynamics, Germany

The need to reduce CO2 emissions of modern diesel powertrains will be intensified in the near future, because of the current European legislation for CO2 emissions and the rising shortage of fossil energy sources,. Using alternative fuels, extracted from biomass, has a high potential to reduce CO2 emissions from their production to their combustion in the engine. A possibility to optimize the mixture formation is the increasing of the injection pressure. The produced spray leads to an optimized mixing of fuel and air and an improved combustion process involved which results in reduced specific fuel consumption and soot emissions. In combination with a rising exhaust gas recirculation, the increasing injection pressure leads to an additional reduction of the nitrogen oxides emissions. The employment of alternative fuels with simultaneous optimizing the mixture formation presents an important mean to reduce the fuel consumption of modern diesel engines. A high pressure injection system is developed in the project "Ultra High Injection of Alternative Diesel Fuels", which is able to inject with an ultra high injection pressure. Simultaenously a pressure chamber has been refited for diesel operation in which a chamber pressure and temperature niveau can be realized up to 60 bar respectevily 500 °C. Ambient conditions like in the combustion chamber of a charged diesel engine during the injection time can be described. The paper presents, results of the spray behaviour, which were measured in a pressure chamber with optical measuring devices at ambient conditions like in the engine. Using a highspeed camera, the macroscopic structure of the spray (spray angle, penetration) will be investigated at different injection pressures and for different alternative fuels. By variation of the fuel and the injection parameters, for example injection pressure and the start of injection, tendencies about the behaviour of the mixture formation with alternative fuels under engine conditions can be derived. With the help of these results statements can be defined for constructive modifications of the nozzle parameters which are important for the mixture formation, like the diameter and the number of nozzle holes, conicity or rate of rounding to optimize the spray characteristic. Furthermore the highspeed investigations are important for definition of the geometric measuring locations in relation to the following measurement with particle dynamic analysis (PDA). Using PDA the global spray is not investigated but the droplets are analyzed regarding to the velocity and the geometric size. Particularly the mean droplet diameter gives information about the quality of the mixture formation and the involved combustion process as well as the formation of emissions. The paper presents the main results of the investigations and concludes with an outlook to ongoing research activities.

This abstract is supplemented by a PDF, which can be viewed here.

Session: IC Engines, Goals and Development