Experimental Investigations on Particle Number Emissions from GDI Engines

Experimental Investigations on Particle Number Emissions from GDI Engines
Author: Markus Bertsch
Publisher: Logos Verlag Berlin GmbH
Total Pages: 170
Release: 2016-12-31
Genre: Technology & Engineering
ISBN: 3832544038

This thesis discusses experimental investigations to reduce particle number emissions from gasoline engines with direct injection. Measures on a single cylinder research engine with combined usage of a particle number measurement system, a particle size distribution measurement system as well as optical diagnostics and thermodynamic analysis enable an in-depth assessment of particle formation and oxidation. Therefore, numerous optical diagnostic techniques for spray visualisation (Mie-scattering, High-Speed PIV) and soot detection (High-Speed-Imaging, Fiber optical diagnostics) are deployed. Two injectors with different hydraulic flows but identical spray-targeting are characterised and compared by measurements in a pressurised chamber. The operation at higher engine load and low engine speed is in the focus of the experimental work at the engine test bench. Thereby, the low flow velocities in the combustion chamber, caused by the low engine speed, as well as the large amount of fuel injected are major challenges for the mixture formation process. A substantial part of the thesis thus focusses on the detailed analysis of the mixture formation process, which is consisting of fuel injection, interaction of the in-cylinder charge motion with the fuel injected and the fuel properties. Measures for the optimisation of the mixture formation process and the minimisation of the particle number emissions are analysed and evaluated. The charge motion is manipulated by the impression of a directed flow, the variation of the valve timings and valve open curve. The injection process is influenced by a reduction of the hydraulic flow of the injector and an increase of the injection pressure up to 50 MPa. The investigations show fundamental effects and potentials of different variation parameters concerning their emissions reduction potential at the exemplary operation at high engine load. Due to the simultaneous analysis of the in-cylinder charge motion and a thermodynamic analysis, the results can be transferred to different engines.

Diesel Engine Transient Operation

Diesel Engine Transient Operation
Author: Constantine D. Rakopoulos
Publisher: Springer Science & Business Media
Total Pages: 408
Release: 2009-03-10
Genre: Technology & Engineering
ISBN: 1848823754

Traditionally, the study of internal combustion engines operation has focused on the steady-state performance. However, the daily driving schedule of automotive and truck engines is inherently related to unsteady conditions. In fact, only a very small portion of a vehicle’s operating pattern is true steady-state, e. g. , when cruising on a motorway. Moreover, the most critical conditions encountered by industrial or marine engines are met during transients too. Unfortunately, the transient operation of turbocharged diesel engines has been associated with slow acceleration rate, hence poor driveability, and overshoot in particulate, gaseous and noise emissions. Despite the relatively large number of published papers, this very important subject has been treated in the past scarcely and only segmentally as regards reference books. Merely two chapters, one in the book Turbocharging the Internal Combustion Engine by N. Watson and M. S. Janota (McMillan Press, 1982) and another one written by D. E. Winterbone in the book The Thermodynamics and Gas Dynamics of Internal Combustion Engines, Vol. II edited by J. H. Horlock and D. E. Winterbone (Clarendon Press, 1986) are dedicated to transient operation. Both books, now out of print, were published a long time ago. Then, it seems reasonable to try to expand on these pioneering works, taking into account the recent technological advances and particularly the global concern about environmental pollution, which has intensified the research on transient (diesel) engine operation, typically through the Transient Cycles certification of new vehicles.