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首页> 外文会议>Homogeneous charge compression ignition engines, 2009 >Detailed Unburned Hydrocarbon Investigations in a Highly-Dilute Diesel Low Temperature Combustion Regime
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Detailed Unburned Hydrocarbon Investigations in a Highly-Dilute Diesel Low Temperature Combustion Regime

机译：高稀释柴油低温燃烧条件下未燃烧碳氢化合物的详细研究

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The objective of this research is a detailed investigation of unburned hydrocarbon (UHC) in a highly-dilute diesel low temperature combustion (LTC) regime. This research concentrates on understanding the mechanisms that control the formation of UHC via experiments and simulations in a 0.48L signal-cylinder light duty engine operating at 2000 r/min and 5.5 bar IMEP with multiple injections. A multi-gas FTIR along with other gas and smoke emissions instruments are used to measure exhaust UHC species and other emissions. Controlled experiments in the single-cylinder engine are then combined with three computational tools, namely heat release analysis of measured cylinder pressure, analysis of spray trajectory with a phenomenological spray model using in-cylinder thermodynamics [1], and KIVA-3V Chemkin CFD computations recently tested at LTC conditions [2]. This study looks at the effect of inlet oxygen concentration, fuel spray targeting, injection event timing, injector sac volume, rail pressure, and boost pressure which are each explored within a defined operation range in LTC. This research compliments simultaneous research which concentrates on understanding the benefits of multiple injections on engine performance and emissions operating in the LTC regime [3]. The results of this research show that total UHC can be divided into light (<6 carbon/molecule) UHC and heavy (≥6 carbon/molecule) UHC emissions. The light UHC closely track with CO having minimum exhaust concentrations on the order of 250 ppm and occur when CO is at its 0.5% minimum. Spray targeting, percent inlet oxygen, and boost pressure variation produce the largest light UHC changes, where as injection pressure has minimal effect. Liquid fuel injected outside the piston bowl, which can occur with early injection, is linked to the heavy UHC components where a 3 times increase is observed relative to later injections where the liquid stays within the bowl. Injector sac-volume experiments suggest the sac volume is a relatively constant source of heavy UHC and can contribute as high as 15% of the total UHC. Based on these results, a simple three-part UHC model is suggested and hypotheses are discussed for the over-rich dominant sources of the unburned hydrocarbons.
机译：这项研究的目的是详细研究高稀释柴油低温燃烧（LTC）方案中的未燃烧碳氢化合物（UHC）。这项研究的重点是通过在0.48L信号缸轻负荷发动机，以2000 r / min和5.5 bar IMEP进行多次注入的条件下进行实验和模拟，来了解控制UHC形成的机理。多种气体FTIR以及其他气体和烟雾排放仪器用于测量UHC废气种类和其他排放。然后，将单缸发动机中的受控实验与三种计算工具结合，即对汽缸压力的热释放分析，使用缸内热力学的现象学喷雾模型对喷雾轨迹的分析[1]和KIVA-3V Chemkin CFD计算最近在LTC条件下进行了测试[2]。这项研究着眼于在LTC中定义的操作范围内探讨的进气氧浓度，燃油喷射目标，喷射事件正时，喷射器囊体积，轨道压力和增压压力的影响。这项研究是对同步研究的补充，该研究集中于了解在LTC体制下多次喷射对发动机性能和排放的益处[3]。这项研究的结果表明，UHC的总排放量可分为轻（<6碳/分子）UHC和重（≥6碳/分子）UHC排放。轻型UHC与最小废气浓度约为250 ppm的CO紧密接触，并在CO最小为0.5％时发生。喷雾目标，入口氧气百分比和增压压力变化会产生最大的UHC轻度变化，而喷射压力的影响最小。可能在早期注入时发生的喷射到活塞碗外部的液体燃料与重的UHC组件相关联，在该组件中，观察到的液体燃料相对于后来停留在碗体内的后期喷射增加了3倍。注射囊体积实验表明，囊体积是重UHC的相对恒定来源，占总UHC的15％。基于这些结果，提出了一个简单的由三部分组成的UHC模型，并讨论了未燃烧碳氢化合物的过度富集主导源的假设。

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