Development of advanced natural gas fueling strategies

重型发动机的天然气燃料为公路货运的温室气体（GHG）排放的显著减少提供了近期途径。与同等柴油相比，尾气管二氧化碳排放量可减少20%。在燃料中添加可再生天然气（RNG）可以显著提高燃料循环效率，而无需对发动机进行进一步修改。然而，未燃烧的甲烷排放是有问题的，并削弱了天然气燃料发动机的温室气体效益。降低CH4排放需要在提高燃油效率要求和降低尾气排放的竞争需求中得到满足，特别是预计尾气排放将进一步减少氮氧化物排放。与此同时，与现有技术相比，发动机必须具有成本竞争力，使性能与可接受的投资回收期相匹配。在应对这些挑战的天然气发动机技术中，先导式压缩点火发动机提供了一条很有前途的途径，但仍然面临挑战。本文提出的工作将开发和评估直接喷射天然气发动机的技术，以：1)确定减少发动机输出氮氧化物排放的途径，以满足未来超低氮氧化物排放标准；2)通过消除或尽量减少对驾驶员喷射的需求来降低燃油系统的复杂性；3)确定CH4排放的机制。UBC的单缸发动机研究将用于确定新的操作策略，并表征相关的燃烧过程、效率和排放。此外，光学可及的单缸发动机将用于表征缸内过程。这个为期5年的项目将培训6名HQP，他们将在能源系统、燃烧、空气质量、仪器、图像处理和数据分析等领域培养技能。通过促进国内丰富燃料的使用，直接喷射天然气发动机的改进将使加拿大受益，最终降低氮氧化物、颗粒和温室气体的排放。

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.