Search Results

A computational fluid dynamics (CFD) model was developed to explore gasoline compression ignition (GCI) combustion. Results were validated with single-cylinder engine (SCE) experiments. It was shown that the CFD model captured experimental results well. Cylinder pressure, heat release and emissions from the CFD model were also used to analyze the performance of GCI combustion with a current heavy-duty diesel engine platform. This work also provides detailed analysis on in-cylinder combustion and emissions using CFD. It was found that multiple injection strategy can deliver desirable fuel stratification profile that benefits both engine and emissions performance. A wave contoured piston was compared with a stepped-lip type piston for both GCI and Diesel combustion scenarios on the same engine platform. Stepped-lip pistons offer an opportunity to use multiple injection strategies to overcome high UHC emissions of GCI combustion when compared to wave pistons.

As an alternative fuel, renewable diesel (RD) could improve the performance of conventional internal combustion engines (ICE) because of its difference in fuel properties. With almost no aromatic content in the fuel, RD produces less soot emissions than diesel. The higher cetane number (CN) of RD also promotes ignition of the fuel, which is critical, especially under low load, and low reactivity conditions. This study tested RD fuel in a heavy-duty single-cylinder engine (SCE) under compression-ignition (CI) operation. Test condition includes low and high load points with change in exhaust gas recirculation (EGR) and start of injection (SOI). Measurements and analysis are provided to study combustion and emissions, including particulate matters (PM) mass and particle number (PN). It was found that while the combustion of RD and diesel are very similar, PM and PN emissions of RD were reduced substantially compared to diesel.

Low carbon emissions policies for the transportation sector have recently driven more interest in using low net-carbon fuels, including biodiesel. An internal combustion engine (ICE) can operate effectively using biodiesel while achieving lower engine-out emissions, such as soot, mostly thanks to oxygenate content in biodiesel. This study selected a heavy-duty (HD) single-cylinder engine (SCE) platform to test biodiesel fuel blends with 20% and 100% biodiesel content by volume, referred to as B20, and B100. Test conditions include a parametric study of exhaust gas recirculating (EGR), and the start of injection (SOI) performed at low and high engine load operating points. In-cylinder pressure and engine-out emissions (NOX and soot) measurements were collected to compare diesel and biodiesel fuels.

Advanced diesel combustion systems continue to push the peak cylinder pressure limit of engines upward to allow high-efficiency combustion with high compression ratios (CR). The air-standard Otto and Diesel cycles indicate increased compression ratios lead to higher cycle efficiency. The study presented here describes the development and demonstration of a high-efficiency diesel combustion system. The study used both computational and experimental tools to develop the combustion system fully. Computational fluid dynamics (CFD) simulations were carried out to evaluate combustion with two combustion systems at a compression ratio of 22:1 with a Wave piston design (based on the production Volvo Wave piston). Analysis of combustion performance and emissions were performed to confirm the improvements these piston designs offered relative to the baseline combustion system for the engine. Companion single-cylinder engine (SCE) experiments were performed to validate the simulation results.