Comparison of fuel properties and emission characteristics of two- and three-phase emulsions prepared by ultrasonically vibrating and mechanically homogenizing emulsification methods
Comparison of fuel properties and emission characteristics of two- and three-phase emulsions prepared by ultrasonically vibrating and mechanically homogenizing emulsification methods
复制标题
DOI：
10.1016/j.fuel.2007.12.017
复制
发表时间：
2008-08
期刊：
影响因子：
7.4
通讯作者：
Cherng-Yuan Lin;Li-Wei Chen
中科院分区：
文献类型：
--
作者：
Cherng-Yuan Lin;Li-Wei Chen
长期以来，乳剂一直被认为是燃烧设备的替代燃料，以达到更好的燃油经济性和减少污染。机械均质法是制备乳剂的常用方法，而采用超声乳化法制备乳剂的方法仍然相当有限，而且大多只适用于两相乳剂。因此，分别通过机械均质机和超声振动器制备了两相W/O和三相O/W/O乳剂，并将其用作发动机燃料。对两种乳化方法的乳化性能、发动机性能和发动机排放特性进行了测试和比较。并对超声乳化法的应用前景进行了评价。实验结果表明，超声振动器制备的乳化液具有更有利的乳化特性，分散水滴更小，在连续油相中分布更均匀，水滴从柴油连续相中分离率更低，从而分散水滴从乳化液中分离率更低，乳化液稳定性更大；并且比使用机械均质机生产的乳液粘度更大。此外，与机械均质器相比，超声振动器制备的乳液乳化水含量更高。超声振动器制备的乳剂具有较低的燃油消耗率、较低的bsfc和较低的CO排放，同时具有较大的黑烟不透明度。对比超声振动器和机械均质器制备的两相W/O和三相O/W/O乳剂，无论是超声振动器还是机械均质器制备的两相W/O乳剂，均表现出比三相O/W/O乳剂具有更低的燃油消耗率、bsfc、CO和更低的黑烟不浊度。
Emulsions have long been considered as an alternative fuel for combustion equipment in order to achieve better fuel economy and pollution reduction. While a mechanical homogenizing method is frequently used to prepare emulsions, the use of an ultrasonic emulsification method to do so is still rather limited, and is mostly applied to two-phase emulsions only. Hence, two-phase W/O and three-phase O/W/O emulsions, prepared by a mechanical homogenizer and an ultrasonic vibrator, respectively, were prepared and used as engine fuel. The emulsion properties, engine performance, and engine emission characteristics between these two emulsification methods were measured and compared. The potential of the ultrasonic emulsification method was also evaluated. The experimental results show that the emulsions prepared by the ultrasonic vibrator appeared to have more favorable emulsification characteristics such as smaller dispersed water droplets that were distributed more uniformly in the continuous oil phase, lower separation rate of water droplets from the continuous phase of diesel fuel and thus a lower separating rate of the dispersed water droplets from the emulsion, larger emulsion stability, and larger emulsion viscosity than the emulsions produced using a mechanical homogenizer. In addition, a larger content of water was emulsified when the emulsion was prepared using the ultrasonic vibrator than the mechanical homogenizer. The emulsions prepared by the ultrasonic vibrator also had a lower fuel consumption rate, lower bsfc, and significantly lower CO emission while at the same time having a larger black smoke opacity. When comparing the two-phase W/O and the three-phase O/W/O emulsions prepared by either the ultrasonic vibrator or the mechanical homogenizer, the two-phase W/O emulsions appeared to have a lower fuel consumption rate, bsfc, CO, and a lower black smoke opacity than the three-phase O/W/O emulsions, regardless of whether they were prepared by ultrasonic vibrator or mechanical homogenizer.