An Experimental Investigation of Reactivity-Controlled Compression Ignition Combustion in a Single-Cylinder Diesel Engine Using Hydrous Ethanol
An Experimental Investigation of Reactivity-Controlled Compression Ignition Combustion in a Single-Cylinder Diesel Engine Using Hydrous Ethanol
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DOI：
10.1115/1.4028771
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发表时间：
2015-05-01
影响因子：
3
通讯作者：
Northrop, William F.
中科院分区：
文献类型：
--
作者：
Fang, Wei;Fang, Junhua;Northrop, William F.
双燃料反应性控制压燃(RCCI)燃烧采用喷嘴喷射活性较低的燃料和早期循环直接喷射活性较高的燃料(DI)，已被证明在发动机广泛的工作范围内既能产生高热效率，又能产生低NOX和碳烟排放。传统燃料和替代燃料如汽油、天然气和E85作为反应活性较低的燃料在RCCI中已经得到了许多研究人员的研究，但关于含水乙醇在RCCI中应用的实验研究很少。在内燃机中更多地使用含水乙醇有可能极大地改善使用生物乙醇的经济性和生命周期的二氧化碳排放。在RCCI燃烧模式下，以150倍量含水乙醇为低反应性燃料，以商品柴油为高反应性燃料，进行了不同负荷下的试验研究。在改装的单缸柴油机上进行了试验。在前人对RCCI燃烧研究的基础上，采用了柴油早循环分流喷射策略来形成缸内燃料反应性分布，以保持较高的热效率和较低的NOX和碳烟排放。在每个负荷条件下，第一次柴油喷射的正时和质量分数保持不变，而第二次柴油喷射的正时被扫过一个可以保持稳定燃烧的范围。由于含水乙醇具有很强的抗自燃性和较大的汽化热，需要进气加热来获得发动机的稳定运行。研究表明，150份含水乙醇可作为RCCI的低反应性燃料，在指示有效压力(IMEP)为8.6bar时，乙醇能量分数可达75%，同时获得较低的NOx和碳烟排放。随着发动机负荷的增加，需要较少的进气加热和废气再循环(EGR)来维持低NOX排放。
Dual-fuel reactivity-controlled compression ignition (RCCI) combustion using port injection of a less reactive fuel and early-cycle direct injection (DI) of a more reactive fuel has been shown to yield both high thermal efficiency and low NOX and soot emissions over a wide engine operating range. Conventional and alternative fuels such as gasoline, natural gas, and E85 as the lower reactivity fuel in RCCI have been studied by many researchers; however, published experimental investigations of hydrous ethanol use in RCCI are scarce. Making greater use of hydrous ethanol in internal combustion engines has the potential to dramatically improve the economics and life cycle carbon dioxide emissions of using bioethanol. In this work, an experimental investigation was conducted using 150 proof hydrous ethanol as the low reactivity fuel and commercially available diesel as the high reactivity fuel in an RCCI combustion mode at various load conditions. A modified single-cylinder diesel engine was used for the experiments. Based on previous studies on RCCI combustion by other researchers, early-cycle split-injection strategy of diesel fuel was used to create an in-cylinder fuel reactivity distribution to maintain high thermal efficiency and low NOX and soot emissions. At each load condition, timing and mass fraction of the first diesel injection was held constant, while timing of the second diesel injection was swept over a range where stable combustion could be maintained. Since hydrous ethanol is highly resistant to auto-ignition and has large heat of vaporization, intake air heating was needed to obtain stable operations of the engine. The study shows that 150 proof hydrous ethanol can be used as the low reactivity fuel in RCCI through 8.6 bar indicated mean effective pressure (IMEP) and with ethanol energy fraction up to 75% while achieving simultaneously low levels of NOX and soot emissions. With increasing engine load, less intake heating is needed and exhaust gas recirculation (EGR) is required to maintain low NOX emissions.