Research

Particle Number Emissions from Gasoline Engines

Owing to its high efficiency, direct injection has established itself as the standard technology in gasoline engines. Compared to external carburetion, however, health-damaging particles are produced. The aim of this project was to analyse the mechanisms for particle formation and in a second step to reduce particle number emissions. To this end, the project partners analysed the carburetion and combustion processes using optical measurement technology. With the use of electron microscopic investigations they gained knowledge about the morphology and the composition of particles. The findings revealed that the essential parameter on particle formation is carburation, which is mainly influenced by the injection system, the charge movement and the injection strategy. The oxygen concentration and the gas temperature profile in the primary zone of the combustion chamber significantly influence particle oxidation. These results form the basis for the further development of emission reduction technologies.

» The investigations provide us with a thorough understanding of the key influencing factors of particle formation in direct injection gasoline engines. We now know which parameters we need to look at to reduce particle number emissions. «
Prof. Dr. sc. techn. Thomas Koch (IFKM | KIT Karlsruhe)

Motivation

Direct injection – the direct injection of fuel in the combustion chamber – together with turbocharging has become a key technology in gasoline (GDI) engines. One disadvantage compared with external formation of the air-fuel mix is, however, an increase in particle emissions in exhaust gas. Owing to their tiny size, these particles can enter the lungs and in this manner are hazardous to health. A thorough understanding of the engine internal sources for particle formation is a prerequisite for avoiding PN emissions.

Methodology

Using optical measurement methods, the carburetion and combustion processes were analysed, the particle concentration and size distribution in exhaust gas were measured, and emitted soot was examined for its morphology and chemical composition using an electron microscopy. A single-stroke engine and one-cylinder aggregate with direct injection and central injector storage served as the test vehicle. At the beginning, the focus of the investigations was on reviewing the influence of different compositions. Then through a restriction of the injector diversity, the influence of different parameters on PN emissions could be established.

Result

The carburetion as a sum of direct injection system, charge movement and injection strategy has the largest influence on particle formation. The particle oxidation is mainly determined by the oxygen concentration and the gas temperature profile in the primary zone of the combustion chamber. The investigation also showed that both spray targeting – the optimal spatial distribution of fuel mixture in the combustion chamber – and wear on components can influence the oil concentration in the exhaust gas and thus also the lubricant oil content of particles. Further investigations offer the possibility of performing the PN measurement directly in the exhaust gas system and of further developing the engine internal data / measured value acquisition.

Documentation

Particles at Otto-DI I | Investigations to reduce particulate-emissions from Otto-DI-engines | Project No. 1046

Particles at Otto-DI II | Investigations into reducing particle number emissions from GDI engines | Project No. 1144

Particles at Otto-DI III | Investigations into reducing particle number emissions from GDI engines | Project No. 1193

Themis

Status
Finalised

Programme
Public & FVV Funding

Budget
820.00,00 EUR

Time Period
2010-08-01 to 2013-07-31 Part I
2013-07-01 to 2014-06-30 Part II
2015-06-01 to 2017-03-31 Part III

Research Association for Combustion Engines (FVV) eV

Lyoner Strasse 18
60528 Frankfurt am Main
Germany

German Federation of Industrial Research Associations (AiF) e. V.

Bayenthalgürtel 23
50968 Cologne
Germany

Federal Ministry for Economic Affairs and Energy (BMWi)

Scharnhorststrasse 34-37
10115 Berlin
Germany

Industry

Dr.-techn. Herwig Richter | I
Dr.-Ing. h. c. F. Porsche AG

Dr.-Ing. Daniel Sabathil
Opel Automobile GmbH | II+III

RTD Performer

Institute of Internal Combustion Engines (IFKM) | Karlsruhe Institute of Technology (KIT)

Head of Research:
Prof. Dr.-Ing. Ulrich Spicher | I
Prof. Dr. sc. techn. Thomas Koch | I-III

Research Associates:
Dipl.-Ing. Markus Bertsch | II+III
Dipl.-Ing. Helge Dageförde | I
Denis Notheis, MSc | III

Karlsruhe Institute of Technology

Institute for Chemical Technology and Polymer Chemistry

Engesserstr. 18 / 20
76131 Karlsruhe
Germany

Project Management

Ralf Thee

FVV
+49 (0) 69 6603 1349
+49 (0) 69 6603 2349


Research Association for Combustion Engines eV

Lyoner Strasse 18
60528 Frankfurt am Main
Germany
T +49 69 6603 1345