Investigation of Puffing and Micro-Explosion of Water-in-Diesel Emulsion Spray Using Shadow Imaging

Abstract

Water-in-diesel emulsions potentially favor the occurrence of micro-explosions when exposed to elevated temperatures, thereby improving the mixing of fuels with the ambient gas. The distributions and sizes of both spray and dispersed water droplets have a significant effect on puffing and micro-explosion behavior. Although the injection pressure is likely to alter the properties of emulsions, this effect on the spray flow puffing and micro-explosion has not been reported. To investigate this, we injected a fuel spray using a microsyringe needle into a high-temperature environment to investigate the droplets’ behavior. Injection pressures were varied at 10% v/v water content, the samples were imaged using a digital microscope, and the dispersed droplet size distributions were extracted using a purpose-built image processing algorithm. A high-speed camera coupled with a long-distance microscope objective was then used to capture the emulsion spray droplets. Our measurements indicated that the secondary atomization was significantly affected by the injection pressure which reduced the dispersed droplet size and hence caused a delay in puffing. At high injection pressure (500, 1000, and 1500 bar), the water was evaporated during the spray and although there was not enough droplet residence time, puffing and micro-explosion were clearly observed. This study suggests that high injection pressures have a detrimental effect on the secondary atomization of water-in-diesel emulsions.

Trending approaches on demulsification of crude oil in the petroleum industry

“…Generally, mixing is inversely proportional to the distributed water droplets in the crude oil and emulsion tighter [1,53]. A previous study on emulsions had suggested that the droplets of water fall within 1 and 1000 µm [27]. Furthermore, the presence of an emulsifier is another important factor; the nature, amount and presence of the emulsifier outline the tightness and nature of an emulsion [1,38].…”

Spraying of Composite Liquid Fuels Based on Types of Coal Preparation Waste: Current Problems and Achievements: Review

“…The thermal atomization mechanism of droplet disintegration is based on the difference between the thermophysical properties of droplet components. This type of atomization can manifest itself when heating inhomogeneous droplets by puffing [30][31][32] or microexplosion [33][34][35][36][37]. Additionally, there are known technologies for the artificial carbonation of liquid fuels in order to use gas bubbles (for example, CO 2 ) as micro-explosion centers [38].…”

A Review of the Emulsification Method for Alternative Fuels Used in Diesel Engines

“…The emulsification process usually involves low quantities or volumes of surfactant, co-surfactant, and water. Previous studies have shown that using emulsified petro-diesel fuel can reduce massive toxic emissions, such as PM, smoke, and NOx, while most studies have also reported an improvement in engine combustion [28][29][30][31]. So far, only a few researchers have reported on emulsification techniques using vegetable oils or animal fats.…”