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The fundamental effects of in-cylinder evaporation of liquefied natural gas fuels in engines
Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering ( IF 1.7 ) Pub Date : 2020-07-28 , DOI: 10.1177/0954407020941710 Joshua Finneran 1 , Colin P Garner 1 , Francois Nadal 1
Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering ( IF 1.7 ) Pub Date : 2020-07-28 , DOI: 10.1177/0954407020941710 Joshua Finneran 1 , Colin P Garner 1 , Francois Nadal 1
Affiliation
Liquefied natural gas is emerging as viable and potentially sustainable transportation fuel with intrinsic economic and environmental benefits. Liquefied natural gas possesses thermomechanical exergy amounting to ∼1 MJ kg-1 which is currently wasted on liquefied natural gas vehicles, while it could be used to produce useful work. The present investigation proposes an indirect means of obtaining useful work from liquefied natural gas through charge cooling and also demonstrates additional benefits in terms of NOx emissions and power density. A thermodynamic engine model was used to quantify the performance benefits of such a strategy for a homogeneous-charge, spark-ignited, stoichiometric natural gas engine. Four fuelling strategies were compared in terms of fuel consumption, mean effective pressure and NOx emissions. Compared to the conventional port-injected natural gas engine (where gaseous fuel is injected), it was found that directly injecting the liquid phase fuel into the cylinder near the start of the compression stroke resulted in approximately -8.9% brake specific fuel consumption, +18.5% brake mean effective pressure and -51% brake specific NOx depending on the operating point. Port-injection of the fuel in the liquid phase carried similar benefits, while direct injection of the fuel in the gaseous phase resulted in minor efficiency penalties (∼+1.3% brake specific fuel consumption). This work highlights the future potential of liquefied natural gas vehicles to achieve high specific power, high efficiency and ultra-low emissions (such as NOx) by tailoring the fuel system to fully exploit the cryogenic properties of the fuel.
中文翻译:
液化天然气燃料缸内蒸发对发动机的基本影响
液化天然气正在成为具有内在经济和环境效益的可行且具有潜在可持续性的运输燃料。液化天然气具有约 1 MJ kg-1 的热机械火用,目前被浪费在液化天然气车辆上,但可用于产生有用的功。本研究提出了一种通过增压冷却从液化天然气中获得有用功的间接方法,并且还展示了在 NOx 排放和功率密度方面的额外好处。热力学发动机模型用于量化这种策略对均质充量、火花点火、化学计量天然气发动机的性能优势。在燃料消耗、平均有效压力和氮氧化物排放方面比较了四种加油策略。与传统的进气道喷射天然气发动机(喷射气体燃料)相比,发现在压缩冲程开始附近直接将液相燃料喷射到气缸中导致大约 -8.9% 的制动比燃料消耗,+ 18.5% 的刹车平均有效压力和 -51% 的刹车特定 NOx 取决于工作点。液相燃料的端口喷射具有类似的好处,而气相燃料的直接喷射导致了较小的效率损失(~+1.3% 的制动比燃料消耗)。这项工作突出了液化天然气汽车通过定制燃料系统以充分利用燃料的低温特性来实现高比功率、高效率和超低排放(如 NOx)的未来潜力。
更新日期:2020-07-28
中文翻译:
液化天然气燃料缸内蒸发对发动机的基本影响
液化天然气正在成为具有内在经济和环境效益的可行且具有潜在可持续性的运输燃料。液化天然气具有约 1 MJ kg-1 的热机械火用,目前被浪费在液化天然气车辆上,但可用于产生有用的功。本研究提出了一种通过增压冷却从液化天然气中获得有用功的间接方法,并且还展示了在 NOx 排放和功率密度方面的额外好处。热力学发动机模型用于量化这种策略对均质充量、火花点火、化学计量天然气发动机的性能优势。在燃料消耗、平均有效压力和氮氧化物排放方面比较了四种加油策略。与传统的进气道喷射天然气发动机(喷射气体燃料)相比,发现在压缩冲程开始附近直接将液相燃料喷射到气缸中导致大约 -8.9% 的制动比燃料消耗,+ 18.5% 的刹车平均有效压力和 -51% 的刹车特定 NOx 取决于工作点。液相燃料的端口喷射具有类似的好处,而气相燃料的直接喷射导致了较小的效率损失(~+1.3% 的制动比燃料消耗)。这项工作突出了液化天然气汽车通过定制燃料系统以充分利用燃料的低温特性来实现高比功率、高效率和超低排放(如 NOx)的未来潜力。