The comparison of oxidative thermokinetics between emulsion and microemulsion diesel fuel
The comparison of oxidative thermokinetics between emulsion and microemulsion diesel fuel
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DOI：
10.1016/j.enconman.2015.05.071
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发表时间：
2015-09
影响因子：
10.4
通讯作者：
Lijian Leng;Xingzhong Yuan;G. Zeng;Hou Wang;Hua-jun Huang;Xiaohong Chen
中科院分区：
文献类型：
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作者：
Lijian Leng;Xingzhong Yuan;G. Zeng;Hou Wang;Hua-jun Huang;Xiaohong Chen
水燃料乳化液具有节能、提高发动机扭矩、改善发动机性能、减少污染物排放等优点，得到了广泛的研究。但其存在相分离、点火延迟长等缺点。以鼠李糖脂为表面活性剂制备了水燃料微乳液，并与水燃料微乳液进行了比较。水燃料微乳液与乳白色乳化液燃料相比，在90天内不进行相分离的热稳定性较好。在热重分析中，随着升温速率的增加，TG和DTG曲线向更高的温度移动。然而，在40k min−1时，乳化液的变化不明显，这意味着传热、传质和汽化速率的降低，并进一步延长了柴油机燃烧时的点火延迟。ozawa - flyn - wall （OFW）、kissinger - akira - sunose （KAS）和Starink的方法预测的活化能（Ea）表明，微乳液的形成使燃料的活化能降低约5 kJ mol−1，而乳液的形成使燃料的活化能提高15 kJ mol−1。微乳化燃料的活化能较低，表明其容易点火或点火延迟时间较短。因此，与乳化相比，微乳化可能是一种更具竞争力的燃料升级技术。
Water fuel emulsion has been widely studied with the advantages of saving energy, enhancing engine torque, improving engine performance, and reducing the pollutant emissions. However, it has unfavorable disadvantages such as phase separation and long ignition delay. Water fuel microemulsion with rhamnolipid as the surfactant was formed in this study and characterized in comparison to water fuel emulsion. Water fuel microemulsion was thermodynamically stable without phase separation after 90 days vs. the milky-white emulsion fuel, separated within 2 days. In the thermogravimetric analysis, the TG and DTG curves were shifted to higher temperatures as the increment of heating rate. However, the shift for emulsion at 40 K min−1was inconspicuous, which implies the reduction in heat transfer, mass transfer, and vaporization rates and further the lengthened ignition delay upon combustion in diesel engine. The activation energies (Ea) predicted by Ozawa–Flynn–Wall (OFW), Kissinger–Akhira–Sunose (KAS), and Starink’s methods indicate that the formation of microemulsion could decrease the activation energy of the fuel by about 5 kJ mol−1, while the formation of emulsion would increase by 15 kJ mol−1. The lower activation energy of microemulsion fuel is an indication of easy ignition or shortened ignition delay. Thus, microemulsification may be a more competitive technique for fuel upgrading compared to emulsification.