Comparison of Water-in-Oil Emulsion Atomization Characteristics for Low- And High-Capacity Pressure-Swirl Nozzles

Abstract

Utilizing water as an additive to liquid fuels is a technique that has the ability to lower combustion-generated pollutant emissions and increase combustion efficiency. The present work investigates the atomization characteristics of various water-in-diesel fuel emulsions stabilized with surfactants through a low-flow-capacity pressure-swirl injector. These results were compared to past results where these emulsions were introduced through a high-flow-capacity nozzle. The emulsions, generated by a mixing device, were characterized by their fluid properties and dispersed water droplet size distributions. An experimental test matrix was produced that features different injection pressures, emulsion qualities, and water-to-diesel fuel mass fractions and enables statistical analysis of these three parameters. The results show that viscosity increases with increasing water concentration, while the surface tension remains similar to that of diesel fuel. This implies that an overall increase in the spray's average droplet size should occur; however, the measured results with the current injector show similar droplet sizes compared to those of pure liquids. The average droplet sizes follow the same trends observed when using an injector with 20 times the flow capacity of the present nozzle. For the range of parameters studied, spray droplet size depends primarily on the injector pressure drop, but the amount of water in the emulsion also has a statistically significant effect. Patternation results show a slight change in the spatial composition of the emulsion spray as a function of the injector pressure differential and discrete droplet size of the emulsion.

Injection of Water-in-Oil Emulsion Jets Into a Subsonic Crossflow: An Experimental Study

“…This has already been well documented by past experiments with injecting emulsions in pressure swirl nozzles (Bolszo, 2011;Bolszo et al, 2010;Narvaez et al, 2011). Also, injection as an emulsion results in measured droplet size distribution shifting to larger droplets at locations farthest from the injection wall but with little change near the wall.…”