Performance improvement of turbocharged SI engine by post-oxidation enhancement in exhaust gas in-homogeneity

Abstract

In this research, the improvement of mixing and pulsation in exhaust manifold with a design and implementation of bypass adapter at exhaust port were deeply investigated. This in-turn can improve the post-oxidation phenomena and hence emissions and engine performance could be enhanced. This research investigation includes 1-D, 3-D simulations and experimental validation on a 4-cylinder turbocharged spark ignition (SI) engine. Firstly, the 1-D and 3-D simulation models were developed and calibrated with the experimental results. Then, the simulations were used for the detailed investigation of mixing and pulsation in exhaust manifold with and without bypass adapter. Thereafter, experimental test for the post-oxidation were conducted with and without consideration of the bypass adapter and results were compared. From the simulation and experimental results, it was proven that by using bypass adapter at the exhaust port, the mixing of exhaust gas species was observed to be significantly improved to some extent. Also, the unbalance between exhaust port and turbocharger upstream gas species were reduced. This also reduced the exhaust gas pulsation. By the improvement of mixing between scavenged O2 and unburned gas species, the post-oxidation reaction was also noted to have improved and consequently the emissions and turbo-speed were found to be better that led to an improved IMEP and thermal efficiency of the engine.

Analysis of Post-oxidation Phenomena in a Turbocharged DISI Engine Focused on Gas and PM Emissions and Gas Temperature

“…This had appeared due to the higher in-homogeneity in secondary combustion that leads to unstable post-oxidation in the exhaust manifold. This can be improved if the mixing of unburned gas species with scavenged O2 will be able to enhanced in the exhaust manifold [7]. The…”

“…At the same time, less unburned fuel is brought into the catalyst, which prevents the catalyst from rising in temperature. In past, another methodology for the post-oxidation has been also adopted such as, secondary air injection in exhaust port that can enable secondary reaction (post-oxidation) and could increase enthalpy at turbocharger upstream and hence turbo-lag can be reduced [3][4][5][6][7].…”

“…The wider investigation on the emissions such as, CO, CO2, THC, PM and H2 have been also performed in the post-oxidation phenomena and found emissions reduction along with the turboperformance improvement [1,2,3,7]. It was also noted that the efficient post-oxidation can be influenced with adequate mixing, temperature level and air and exhaust gas concentration in the exhaust manifold [7,8]. Also, it is well known that the temperature variation directly reflects the heat generated during the post-oxidation phenomena.…”

Post-oxidation phenomena enhancement with scavenging and secondary air injection in exhaust manifold of a turbocharged GDI engine

“…Also, the inhomogeneity plays a significant drawback at the higher overlap which restricts the efficient postoxidation. 4,5,9,10 Several kinds of simulative and experimental research have been conducted on the scavenging (VVT tuning) based post-oxidation phenomena. [1][2][3][4][5][6][7]9,11,12 Guenther et al performed a simulative study on the scavenging-based post-oxidation phenomena.…”

“…4,5,9,10 Several kinds of simulative and experimental research have been conducted on the scavenging (VVT tuning) based post-oxidation phenomena. [1][2][3][4][5][6][7]9,11,12 Guenther et al performed a simulative study on the scavenging-based post-oxidation phenomena. The reaction kinetics mechanism including CO and H 2 was investigated and found that the H 2 shows the key element for the fast reaction.…”