Development of advanced natural gas fueling strategies

为重型发动机提供天然气燃料提供了一条近期有效减少道路货运温室气体(GHG)排放的途径。与同等柴油相比，尾气二氧化碳排放量减少约20%是可以实现的。在燃料中添加可再生天然气(RNG)可提供显著的燃料循环优势，而无需对发动机进行进一步修改。然而，未燃烧的CH4排放是有问题的，并侵蚀了天然气燃料发动机的温室气体好处。更低的CH4排放需要满足提高燃油效率要求和降低尾气排放的相互竞争的要求，特别是预期将进一步减少尾气中的NOx排放。与此同时，发动机必须与现有技术相比具有成本竞争力，使性能与增量成本的可接受回收期相匹配。在应对这些挑战的天然气发动机技术中，飞行员点火的压燃式发动机提供了一条很有希望的途径，但仍面临挑战。本文建议的工作将开发和评估直接喷射天然气发动机的技术，以：1)确定减少发动机排气NOx排放的途径，以满足未来超低NOx排放标准；2)通过消除或最大限度地减少对预喷的需求，降低燃料系统的复杂性；以及3)确定造成CH4排放的机制。UBC的单缸研究发动机将被用来确定新的运行策略，并表征相关的燃烧过程、效率和排放。此外，一个光学接近的单缸发动机将被用于表征缸内过程。这个为期五年的项目将培训六名HQP，他们将在以下领域建立技能：能源系统、燃烧、空气质量、仪器仪表、图像处理和数据分析。直接喷射天然气发动机的改进将使加拿大受益，因为它促进了国内丰富燃料的使用，最终导致更低的NOx、颗粒物和温室气体排放。

Natural gas fueling for heavy-duty engines offers a near-term path to meaningful reductions in greenhouse gas (GHG) emissions from on-road freight transport. Tailpipe CO2 emission reductions on the order of 20% relative to equivalent diesel are achievable. Adding renewable natural gas (RNG) to the fuel offers significant fuel-cycle benefits without requiring further modifications to the engine. However, unburned CH4 emissions are problematic and erode the GHG benefits of NG fueled engines. Lower CH4 emissions need to be met within the competing demands of increasing fuel efficiency requirements and lower tailpipe emissions, in particular anticipated further reductions in tailpipe NOx emissions. At the same time, the engines must be cost-competitive with incumbent technologies, matching performance with an acceptable payback period for incremental costs. Of the NG engine technologies to meet these challenges, pilot-ignited compression ignition engines offer a promising pathway, but still face challenges. The work proposed herein will develop and evaluate technologies for direct injection NG engines to: 1) identify routes to reduce engine-out NOx emissions to meet future ultra-low NOx emissions standards; 2) reduce the fuel system complexity by eliminating or minimizing the need for a pilot injection, and; 3) identify the mechanisms responsible for CH4 emissions. A single cylinder research engine at UBC will be utilized to identify new operating strategies and to characterize the associated combustion process, efficiency, and emissions. In addition,an optically accessible single cylinder engine will be used for characterizing the in-cylinder processes. This five-year project will train six HQP, who will build skills in the areas of: energy systems, combustion, air quality, instrumentation, image processing, and data analysis. The improvements in direct injected NG engines will benefit Canada by facilitating the use of a domestically abundant fuel, ultimately resulting in lower, NOx, particulate, and GHG emissions.