AI Summary & Key Takeaways
AI InsightThese results demonstrate that optimizing SOC timing and incorporating hydrogen into methane can enhance engine performance while managing emissions and avoiding knock, contributing to the development of sustainable fuel technologies.
📌 3 Key Takeaways
Abstract
Natural gas has gained attention as a promising alternative fuel to reduce emissions and reliance on petroleum-based fuels. However, its combustion limitations, such as a low lean air-fuel mixture limit and high ignition energy requirements, can be improved by adding hydrogen. This study aims to address these limitations and investigate how adding hydrogen can improve the combustion properties of natural gas. In this study, a 3-cylinder diesel heavy-duty engine with a compression ratio of 17.5:1 was converted to a spark-ignition engine using natural gas with 10% hydrogen by mass. The effects of different start of combustion (SOC) timings (0°, -5°, -10°, -15°, and -20° CA) on engine performance and emissions were analyzed under full-load conditions at 2300 rpm using a 0/1-dimensional combustion simulation program. The best SOC timing was -5° CA, producing the highest brake power (BP) of (78.8 kW) and lowest brake specific fuel consumption(BSFC) of (168.37 g/kWh), improving brake power (BP by 1.18% and reducing (BSFC) by 1.42% compared to the baseline. SOC timings of -5° and -10° CA are operated safely without knocking, with maximum pressure rise rate (MPRR) values of 0.61 MPa/°CA and 0.87 MPa/°CA, respectively, while 15° and -20° CA exceeded the knock limit of 1 MPa/°CA. Advancing SOC to -20° CA increased nitrogen oxides (NOX) emissions by 1.52 times due to higher in-cylinder temperatures. These results demonstrate that optimizing SOC timing and incorporating hydrogen into methane can enhance engine performance while managing emissions and avoiding knock, contributing to the development of sustainable fuel technologies. Careful calibration of SOC is necessary to avoid damaging components while maximizing performance.