Low Emission Diesel Combustion System by Use of Reformulated Fuel with Liquefied CO2 and n-Tridecane

提出了一种利用溶解液化二氧化碳的柴油(正十三烷)同时降低柴油机排气中NO和碳烟排放的新方法。溶解的CO2组分在喷射到燃烧室时可能会经历闪蒸或气体分离，并改善喷雾雾化和混合过程，这两个因素都是控制碳烟形成的主要因素。此外，燃料中注入的二氧化碳成分所引起的内部EGR效应预计会对NO的生成产生影响。为了验证这一概念，在环境压力和温度变化的恒容容器中进行了喷雾动力学测量。此外，利用快速压缩膨胀机进行了燃烧试验。用阴影照相法和双色法研究了蒸发混合燃料喷雾的特性，以评价定性火焰温度和碳烟浓度。试验结果表明，柴油-液化二氧化碳混合燃料在保持和提高燃烧系数的前提下，可以成功地降低柴油燃烧过程中的NO和碳烟排放。

We propose a new on simultaneous reduction of NO and soot emission in Diesel engine exhaust by use of the diesel fuel oil (n-Tridecane) with liquefied CO2 dissolved. The CO2 dissolved component is expected to undergo flash boiling or gas separation when being injected into the combustion chamber, and improve spray atomization and mixing process both of which are primary factor to govern soot formation. Further, the internal EGR effect caused by CO2 component injected with the fuel is expected for NO formation. In order to assess this concept, spray dynamics measurement was conducted in the constant volume vessel with a variation of ambient pressure and temperature. Further, combustion experiments were carried out by using a rapid compression and expansion machine. Here, characteristics of the evaporative mixed fuel spray were examined by shadowgraph photography and two-color method to assess the qualitative flame temperature and soot concentration. From the results, it is revealed that the Diesel fuel-liquefied CO2 mixed fuel can successfully reduce NO and soot emissions in Diesel combustion process with keeping and improving the combustion coefficient.