Impact of counter-bore nozzle on the combustion process and exhaust emissions for light-duty diesel engine application

Abstract

This article describes the main results of an investigation about counter-bore injector nozzle impact on the combustion process in a modern Euro 6 diesel engine. First, hydraulic and spray visualization tests have been performed, showing a potential advantage of such nozzle design in fuel–air mixing efficiency. Then, combustion performance has been assessed on a GM-designed 1.6-L four-cylinder engine. The engine has been installed on a dynamometric test bench and instrumented with an AVL cylinder pressure transducer for heat release rate analysis, as well as HORIBA MEXA gas analyzer for exhaust emissions and AVL 415 Smoke Meter. Engine efficiency and emissions have been analyzed on four different part-load steady-state points, representative of New European Driving Cycle and Worldwide harmonized Light duty Test Cycle certification cycles, and covering engine speeds from 1250 to 2000 r/min and brake mean effective pressure between 0.2 and 1.4 MPa. Results of indicated analysis show that counter-bore nozzles have significant differences in terms of pilot injection combustion at low load points, which in turn lead to a better ignition and shorter combustion of the main injection. In addition, an improvement of diffusive combustion is observed as load increases. Because of both, fuel consumption is reduced by approximately 1% with respect to a standard nozzle. Finally, an appreciable decrease in engine exhaust emissions has been recorded, especially in terms of particulate matter and hydrocarbon emissions. This reduction has been linked to the improvement of fuel–air mixing promoted by the counter-bore nozzle previously observed.

Why the Development of Internal Combustion Engines Is Still Necessary to Fight against Global Climate Change from the Perspective of Transportation

“…A horrible wrong decision from a management and engineering point of view at a specific time and place has generated a worldwide butterfly effect in the automotive industry. However, making the problem a virtue, Dieselgate has forced new regulations to obtain much more efficient and cleaner ICEs [8][9][10][11].…”

“…Limitations to greenhouse gases (CO 2 ), gaseous pollutants, and noise emissions will be increasingly severe, forcing the automotive industry to invest in more innovative technologies for their reduction [10,[27][28][29][30]. Real driving emissions tests are being adopted in the major global economic zones as this strategy expands the ICE operational range in which the pollutant emissions must be kept below the approval limits [31][32][33].…”

Editorial — ‘Thermo- and Fluid-Dynamic Processes in Direct Injection Engines’: THIESEL 2018 Special Issue by Xandra Margot

“…Uchida and Watanabe 3 used single-cylinder experiments and visualization, as well as CFD, to study the ways of improving brake thermal efficiency and reducing heat losses using a new combustion control concept based on multiple fuel injectors to optimize the cycle. Payri et al 4 investigated the impact of counter-bore nozzle on the combustion process of a diesel engine by hydraulic and spray visualization, and confirmed in a real engine its benefits on fuel-air mixing, with a 1% fuel consumption improvement and a significant decrease in particulate matter (PM) and hydrocarbon (HC) emissions with respect to a standard nozzle.…”

“…The paper selection covers all topics of the conference, reflecting current research trends, from the most traditional ones such as injection, sprays and combustion [1][2][3][4][5] to more recent pre-occupations such as studies to improve engine thermal management, [6][7][8] understanding the source of various emissions such as unburned hydrocarbons (UHC) and nanoparticles 9,10 or determining adequate gas exchange strategies for an efficient operation of exhaust after-treatment devices and for emission reduction in cold-start conditions. 11,12 Research on injection and sprays is still a hot topic, for diesel as well as gasoline direct injection (GDI) engines, as it is very relevant to understand the combustion process and the emissions.…”

“…11,12 Research on injection and sprays is still a hot topic, for diesel as well as gasoline direct injection (GDI) engines, as it is very relevant to understand the combustion process and the emissions. In fact, three of the works 1,4,5 included in this Special Issue have been developed in the frame of the Engine Combustion Network (ECN), an international collaborative work programme that aims at providing fundamental understanding of injection and combustion processes as well as reliable data for the validation of computational models.…”