ID#: 142
Abstract Title: Control of Single Droplet Combustion and Emission
Session Title: Multi-phase Combustion I
Session Date: 7/31/01
Session Start Time: 3:40 PM
Contributing Author: FROLOV, S.M.
Organization: Semenov Institute of Chemical Physics
Country: Russia
Authors: Frolov S.M., Posvyanskii V.S. et al, Esmilaire O., Jablon C. et al
Short Abstract: The ultimate objective of the research summarized in this paper is to compare combustion and pollutant-emission performances of pure-fuel and emulsified-fuel droplets. The paper describes the mathematical model of droplet combustion and the results of its implementation. As an example of a heavy hydrocarbon fuel and volatile component, n-tetradecane and water were used. Fuel-water emulsion of this type simulates the performance of Aquazole - a new emulsified fuel for heavy-duty diesel engines. It has been shown that addition of a volatile liquid component to a hydrocarbon fuel allows one to control droplet combustion and emission performances by decreasing the amount of fuel vapor accumulated between the flame and the droplet surface and displacing the flame closer to the surface. As a consequence, more intense interphase fluxes occur, affecting the droplet lifetime and pollutant emission. The main distinctive feature of the emulsion droplet gasification is the existence of a relatively long (up to 80% of the droplet lifetime) period of droplet expansion due to formation of steam bubbles in the droplet interior. The predicted overheat of steam bubbles attains 100-150 K. Gasification of a single emulsion droplet of diameter d exhibits a fast stage of droplet surface regression after passing the maximum in the 'd-squared - time' curve. This stage can be conditionally treated as the microexplosion stage. Combustion of fuel - water emulsion droplets was shown to exhibit significantly less soot and nitrogen oxide emission indices as compared to pure-fuel droplets.