Numerical studies on the mixing characteristics of exhaust gas recirculation gases with air, and their dependence on system geometries in four-cylinder engine applications

• Published in: Proceedings of the Institution of Mechanical Engineers. Part D, Journal of automobile engineering Vol. 223; no. 4; pp. 585 - 597
• Main Authors: Kim, J N, Kim, H Y, Yoon, S S, Sohn, J H, Kim, C R
• Format: Journal Article
• Language: English
• Published: London, England SAGE Publications 01.04.2009; Sage Publications; SAGE PUBLICATIONS, INC
• Subjects: Air flow; Applied sciences; Atmospheric pollution; Combustion; Control systems; Control valves; Diesel engines; Economics; Emissions; Engine cylinders; Engines; Engines and turbines; Exact sciences and technology; Exhaust gases; Exhaust systems; Gas flow; Internal combustion engines: gazoline engine, diesel engines, etc; Mathematical models; Mechanical engineering. Machine design; Nitrogen oxides; Numerical analysis; Optimization; Performance evaluation; Pollution; Pollution sources. Measurement results; Product design; Reliability; Stress concentration; Symmetry; Systems analysis; Three dimensional models; Trucking industry; Variability; exhaust gas recirculation distribution; individual exhaust gas recirculation; exhaust gas recirculation; linked single exhaust gas recirculation; mixing characteristics; Nitrogen oxide; mixing char; Variable geometry; Motor fuel injection; Gas mixture; Engine cylinder; Engine intake; acteristics; Experimental study; Pollutant emission; Modeling; Operating conditions; Carburetor; Exhaust gas recirculation; Gas manifold; Air intake; Air pollution; Internal combustion engine; Reliability
• ISSN: 0954-4070; 2041-2991
• DOI: 10.1243/09544070JAUTO1040

Abstract To achieve low nitrogen oxide (NO x ) emissions and combustion reliability, the variation in the geometry of the exhaust gas recirculation (EGR) system should be optimized. However, the layout process essentially fixes the position of a conventional EGR system, and modifying the intake manifold geometry tends to be economically unjustifiable for a commercial engine. In the present study, two types of EGR system, namely ‘linked single’ and ‘individual’ EGR systems, are proposed and their performances are evaluated numerically. Parametric studies were performed using a three-dimensional numerical model to assess the mixing uniformity of the intake air and EGR gases. The distribution of the mixed gases into the four runners, which force the mixed gases into the four combustion cylinders, is predicted. Three different geometries of the EGR system are considered: single, side-feed individual, and top-feed individual configurations. These geometries reflect the means by which the EGR gases are supplied into the four cylinders. These three configurations are called cases A, B, and C respectively, and their corresponding detailed geometries are identified as A1 to A9, B1 to B17, and C1 to C10, which give a total of 36 computational runs. It was found that case A5 with a hole angle of 60° yielded the most optimal operating mixing and distribution condition. In general, the single systems were found to be superior to the individual systems, among which the top-feed system tended to be slightly more advantageous for mixing than the side-feed individual system owing to the symmetric supply of the top-feed system. The flow of the throttle-valve system, which controls the mass flowrate of the intake air, was used as the validation case; Hyundai-Kia Motor Co. provided the experimental data, which were compared with the computational results.