The Effect of Fuel Injection Equipment of Water-In-Diesel Emulsions on Micro-Explosion Behaviour

The number and size distributions of the water dispersed phase have a significant effect on both the long-term stability of an emulsion, and the probability of micro-explosions inside an engine. The emulsions are subjected to intense pressure and shear flow in the fuel injection equipment resulting...

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Bibliographic Details
Published inEnergies (Basel) Vol. 11; no. 7; p. 1650
Main Authors A. Ismael, Mhadi, R. Heikal, Morgan, A. Aziz, A., Crua, Cyril
Format Journal Article
LanguageEnglish
Published Basel MDPI AG 2018
Subjects
Coalescence
Coalescing
Delay
Diesel
Diesel fuels
dispersed water droplet
Dispersion
Droplets
Emulsions
Explosions
Fuel injection
High speed cameras
Injection
injector shearing
micro-explosion
Nozzles
Pressure
puffing
Shear flow
Size distribution
Stability
Temperature requirements
Thermocouples
water-in-diesel
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Summary:The number and size distributions of the water dispersed phase have a significant effect on both the long-term stability of an emulsion, and the probability of micro-explosions inside an engine. The emulsions are subjected to intense pressure and shear flow in the fuel injection equipment resulting in changes in the number and size distributions of the dispersed phase. These changes, in turn, have significant effects on the micro-explosion behavior of the droplets. To our knowledge, these effects are not known and have not been reported previously. To uncover some of these effects we carried out a comprehensive experimental investigation on an emulsion spray of 10% water (by volume) in diesel at different injection pressures of 500, 1000 and 1500 bar. A measurement system consisting of a high-speed camera was used to visualize the droplets’ micro-explosions and a thermocouple measured the temperature. Our measurements indicated that the emulsion shear in the injector nozzle shifted the emulsion droplet size distribution towards the smaller end resulting in a delay in the onset of micro-explosion. This delay in the onset of the micro-explosion is thought to be due to the decrease in the dispersed water coalescence rate which, in turn, increases the stability of the emulsion. The results also show that this delay in the onset of micro-explosion, and the temperature required for its onset, increased with injection pressure.
ISSN:1996-1073
1996-1073
DOI:10.3390/en11071650