Experimental investigation into the combustion characteristics of a methanol-Diesel heavy duty engine operated in RCCI mode
Experimental investigation into the combustion characteristics of a methanol-Diesel heavy duty engine operated in RCCI mode
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DOI：
10.1016/j.fuel.2018.03.088
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发表时间：
2018-08-15
期刊：
影响因子：
7.4
通讯作者：
Denbratt, Ingemar
中科院分区：
文献类型：
--
作者：
Jia, Zhiqin;Denbratt, Ingemar
本研究使用三种不同的甲醇喷射配置检查双燃料甲醇-柴油重型发动机的燃烧情况：进气歧管的端口喷射；进气冲程期间的直接喷射 (DI_E) 和压缩冲程期间的直接喷射 (DI_L)。后两种甲醇直接喷射配置用于尝试减少 HC 和 CO 排放，这些排放在端口喷射高辛烷值燃料 RCCI 燃烧中相当高。使用双柴油喷射策略进行发动机实验，其中两次先导柴油喷射（PI1 和 PI2）以及 1500 rpm 的恒定发动机转速。在 5 bar IMEP 下对三种甲醇喷射配置研究了三个参数（PI1 和 PI2 喷射正时以及 PI2/PI1 持续时间比）的影响。不稳定燃烧的开始和过度燃烧定相提前对研究参数的扫描施加了下限或上限。 DI_L 配置的净指示热效率低于其他两种甲醇喷射配置。还研究了 5 bar IMEP 下 DI_L 配置的甲醇喷射压力和甲醇替代百分比 (MSP) 的影响，结果表明燃烧过程对甲醇喷射压力相对不敏感，但会受到增加 MSP 的不利影响。最后，在各种负载下测试了端口和 DI_L 配置。在净指示热效率或 HC 和 CO 排放方面，这两种配置都比纯柴油燃烧没有任何优势，但两者在所有负载点都提供较低的温室气体排放。然而，只有甲醇端口喷射配置在 12 bar IMEP 下实现了超低 NOx 和烟灰排放。
This study examines combustion in a dual-fuel methanol-Diesel heavy duty engine using three different methanol injection configurations: port injection into the intake manifold; direct injection during the intake stroke (DI_E) and direct injection during the compression stroke (DI_L). The latter two methanol direct injection configurations were used in the attempt to reduce HC and CO emissions, which were considerably high in the portinjected high-octane fuel RCCI combustion. Engine experiments were performed using a double Diesel injection strategy with two pilot Diesel injections (PI1 and PI2) and a constant engine speed of 1500 rpm. The effects of three parameters-the PI1 and PI2 injection timings, and the PI2/PI1 duration ratio - were investigated at 5 bar IMEP for the three methanol injection configurations. The onset of unstable combustion and excessive combustion phasing advancement imposed lower or upper limits on the sweeps over the studied parameters. The DI_L configuration achieved lower net indicated thermal efficiencies than the other two methanol injection configurations. The influences of the methanol injection pressure and methanol substitution percentage (MSP) were also investigated for the DI_L configuration at 5 bar IMEP, revealing that the combustion process was relatively insensitive to the methanol injection pressure but was adversely affected by increasing the MSP. Finally, the port and DI_L configurations were tested at various loads. Neither configuration offered any advantage over pure Diesel combustion in terms of net indicated thermal efficiency nor emissions of HC and CO, but both offered lower greenhouse gas emissions at all load points. However, only the methanol port injection configuration achieved ultra-low NOx and soot emissions at 12 bar IMEP.