Transient thermal efficiency enhancement of gasoline turbocharged direct injection engines using intake manifold air boosting assistance

Abstract

Improving drivability performance requires enhancing the engine’s typical thermal efficiency and power output during transient manoeuvres, which depends highly on cylinder contents. To achieve the required improvement, an investigation of intake manifold air-boosting assistance for turbocharged direct-injection gasoline engines is considered. Comprehensive modeling of vehicle powertrains for evaluating common low- to medium-load and speed transients is adopted in this contribution. The modeling includes gas-exchange processes, turbocharger response, and vehicle dynamics, especially during lean stratified mode. It allows evaluation of possible improvements to common low- to medium-speed vehicle dynamics that represent urban driving conditions. Thus, it helps to enforce the global intermediate green transition. A four-stroke, four-cylinder engine was used for this purpose, including the required vehicle specifications. The adopted air-boosting assistance technique is simple and innovative. It allows for accurate representation of in-cylinder charge density variations of current internal combustion engine technologies, including those using e-fuels and hybrid powertrains. To that end, the presented results demonstrate how thermal efficiency could be enhanced during engine transients using air boosting in the intake manifold, immediately realizing a high boost pressure (1.75-2.25 bar) and reducing turbo lag by increasing the trapped mass (3.1-4.9 gm). Under various engine speeds (1000-3000 rpm) and load conditions, the results show significant improvements in mean effective pressure and torque due to high-pressure boosting assistance, but moderate changes in thermal efficiency, while maintaining engine power and torque output. Effectively, demonstrates improved performance with environmental benefits.