Extension and experimental validation of models from continuous thermodynamics for numerical simulation of the evaporation of multi-component fuel droplets
Final Report Abstract
The main outcome of this research project consists in an improved knowledge about the effects of heat transfer in the simulation of multi-component droplet evaporation at low temperatures. While temperature is commonly assumed constant in other publications, it was demonstrated that the role of heat transfer in droplet vaporization becomes more important as ambient temperature decreases and may affect the total evaporation time of the droplet. This should be considered for application of a fully diffusion-limited multi-component droplet evaporation model. Furthermore, the semi-continuous mixture approach allows a reduction of the number of equations needed to describe the composition from 5 to 4 in the case of E85. High efforts have been assigned to the experimental setup, combining a gravimetric and optical detection of the droplet chain and its characteristics and quality. In view of this fact, high measurement accuracy could be obtained. Simulations at high temperature show a good agreement with these measurements. Furthermore the experimental determination of the droplet velocity shows a decreasing falling speed along the observed distance. In literature a constant falling speed that results from the drafting effect is often suggested. So the validity of this suggestion should be verified especially if the distance between the droplets is enlarged. Further investigations should validate the simulation at low temperatures and for smaller droplets with a single component present in large quantities in a continuous multi-component mixture. The experimentally validated simulation of droplet evaporation of discrete substances and continuous mixtures is interesting for the international automotive industry. There it is applicable for designing injection systems and engines for flex fuels like E85.
Publications
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Numerical investigation of semi-continuous mixture droplet vaporization at low temperature. Chemical Engineering Science, 2010. 65(18): p. 5137-5145
Rivard E., Brüggemann D.
