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首页> 外文会议>ASME Internal Combustion Engine Division technical conference >Influence of charge motion and compression ratio on the performance of a combustion concept employing in-cylinder gasoline and natural gas blending
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Influence of charge motion and compression ratio on the performance of a combustion concept employing in-cylinder gasoline and natural gas blending

机译：充气运动和压缩比对采用缸内汽油和天然气混合的燃烧概念性能的影响

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The present paper represents a small piece of an extensive experimental effort investigating the dual-fuel operation of a light-duty spark ignited engine. Natural gas (NG) was directly injected into the cylinder and gasoline was injected into the intake-port. Direct injection of NG was used in order to overcome the power density loss usually experienced with NG port-fuel injection as it allows an injection after intake valve closing. Having two separate fuel systems allows for a continuum of in-cylinder blend levels from pure gasoline to pure NG operation. The huge benefit of gasoline is its availability and energy density, whereas NG allows efficient operation at high load due to improved combustion phasing enabled by its higher knock resistance. Furthermore, using NG allowed a reduction of carbon dioxide emissions across the entire engine map due to the higher hydrogen-to-carbon ratio. Exhaust gas recirculation (EGR) was used to (a) increase efficiency at low and part-load operation and (b) reduce the propensity of knock at higher compression ratios (CR) thereby enabling blend levels with greater amount of gasoline across a wider operating range. Two integral engine parameters, CR and in-cylinder turbulence levels, were varied in order to study their influence on efficiency, emissions and performance over a specific speed and load range. Increasing the CR from 10.5 to 14.5 allowed an absolute increase in indicated thermal efficiency of more than 3% for 75% NG (25% gasoline) operation at 8 bar net indicated mean effective pressure and 2500 RPM. However, as anticipated, the achievable peak load at CR 14.5 with 100% gasoline was greatly reduced due to its lower knock resistance. The in-cylinder turbulence level was varied by means of tumble plates as well as an insert for the NG injector that guides the injection "spray" to augment the tumble motion. The usage of tumble plates showed a significant increase in EGR dilution tolerance for pure gasoline operation, however, no such impact was found for blended operation of gasoline and NG.
机译：本文只是研究轻型火花点火发动机的双燃料运行的广泛实验工作的一小部分。天然气（NG）直接注入气缸，汽油注入进气口。使用NG的直接喷射是为了克服NG进气道燃料喷射通常会遇到的功率密度损失，因为它允许在进气门关闭后进行喷射。具有两个独立的燃油系统，可实现从纯汽油到纯天然气运行的连续缸内混合水平。汽油的巨大好处在于它的可用性和能量密度，而NG由于其较高的耐爆震性而改善了燃烧定相，因此可以在高负荷下高效运行。此外，由于更高的氢碳比，使用NG可以减少整个发动机图的二氧化碳排放量。废气再循环（EGR）用于（a）在低负荷和部分负荷运行时提高效率，以及（b）在较高压缩比（CR）下降低爆震的倾向，从而在更宽的运行范围内实现掺混量更高的汽油范围。为了研究它们在特定速度和负载范围内对效率，排放和性能的影响，改变了两个整体发动机参数，即CR和缸内湍流水平。将CR从10.5增加到14.5，可以使在8巴净值指示平均有效压力和2500 RPM的情况下，对于75％NG（25％汽油）运行的指示热效率绝对增加超过3％。但是，正如预期的那样，由于其较低的抗爆震性，使用100％汽油时在CR 14.5处可达到的峰值负荷大大降低了。缸内湍流度通过翻转板以及用于NG喷射器的插件来改变，该插件引导喷射“喷雾”以增强翻转运动。滚筒板的使用显示了纯汽油运行中EGR稀释耐受性的显着提高，但是，汽油和NG的混合运行没有发现这种影响。

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