Pan Donghui, Sun Wanchen, Guo Liang, Zhang Hao, Lin Shaodian, Jiang Mengqi
State Key Laboratory of Automotive Simulation Control, Jilin University, Changchun 130025, China.
Jilin Jianzhu University, Changchun 130118, China.
ACS Omega. 2024 Apr 10;9(16):18191-18201. doi: 10.1021/acsomega.3c10315. eCollection 2024 Apr 23.
An experimental study was carried out on a modified single-cylinder dual-fuel engine in reactivity-controlled compression ignition (RCCI) mode using pilot fuels with different physicochemical properties, and the effects of the pilot fuels and the two-stage injection strategy on the combustion and emission characteristics of the RCCI mode were explored. The results show that when coal-to-liquid (CTL) is used with a high cetane number as the pilot fuel, the reactivity stratification of the fuel-air mixture is more pronounced. With the advancement of pilot injection timing (SOI1), the heat release rate (HRR) of the CTL/gasoline mode gradually changes from a bimodal pattern to a unimodal pattern. Among them, the bimodal HRR includes CTL premixed combustion and gasoline flame propagation, as well as CTL diffused combustion and gasoline multipoint spontaneous combustion, while the unimodal HRR represents CTL premixed combustion and gasoline multipoint spontaneous combustion. However, the HRR of the fossil diesel/gasoline RCCI combustion mode always exhibits a unimodal form. With the advancement of the main injection timing (SOI2), the gravity center of heat release (CA50) is more advanced when using CTL as the pilot fuel due to the short ignition delay. Overall, compared to fossil diesel, using CTL as the pilot fuel is conducive to controlling the pressure rise rate, which expands the operating range of the RCCI combustion mode. Besides, for both pilot fuels of CTL and fossil diesel, the advancement of SOI1 lowers particle emissions, and the advancement of SOI2 reduces NOx emissions, while the two-stage injection achieves higher indicated thermal efficiency.
在反应控制压缩点火（RCCI）模式下，对一台改装的单缸双燃料发动机进行了实验研究，使用了具有不同理化性质的引燃燃料，探讨了引燃燃料和两级喷射策略对RCCI模式燃烧和排放特性的影响。结果表明，当使用十六烷值较高的煤制油（CTL）作为引燃燃料时，燃料 - 空气混合物的反应性分层更为明显。随着引燃喷射正时（SOI1）的提前，CTL/汽油模式的放热率（HRR）逐渐从双峰模式转变为单峰模式。其中，双峰HRR包括CTL预混燃烧和汽油火焰传播，以及CTL扩散燃烧和汽油多点自燃，而单峰HRR表示CTL预混燃烧和汽油多点自燃。然而，化石柴油/汽油RCCI燃烧模式的HRR始终呈现单峰形式。随着主喷射正时（SOI2）的提前，由于点火延迟短，使用CTL作为引燃燃料时放热重心（CA50）更提前。总体而言，与化石柴油相比，使用CTL作为引燃燃料有利于控制压力上升速率，从而扩大了RCCI燃烧模式的运行范围。此外，对于CTL和化石柴油这两种引燃燃料，SOI1提前可降低颗粒物排放，SOI2提前可降低NOx排放，而两级喷射可实现更高的指示热效率。
