Combustion Characteristics of Ethanol-Based Gel Fuel Droplet with Al Powder Under Different Oxidant Concentration Convection

Abstract

Combustion behaviors of non-metallized and metallized gel droplets were investigated using a single-droplet experiment method. Ethanol–methylcellulose gel was used to represent non-metallized gel. Mixed ethanol–methylcellulose gel with 10% aluminum powder was used to represent metallized gel. The gel droplet combustion was conducted at an oxygen concentration of 21% (air), 30%, 40% (enriched air) under an initial convection temperature of approximately 700 (±20) °C. The initial droplet diameter was 2.27 ± 0.19 mm in combustion tests. Furthermore, combustion residuals of metallized gel droplets were analyzed using scanning electron microscopy (SEM) and X-ray diffractometer (XRD). Observations showed that non-metallized and metallized gel droplets led to different combustion behaviors. The combustion of metallized gel droplets showed a particular phenomenon recognized as Al agglomerate period before the end of combustion, which could contribute to the release of more energy of gel fuel. Effects of oxygen concentration on combustion were also evaluated. The results suggest that increased oxygen concentration might improve the combustion efficiency of both non-metallized and metallized gel fuel. Furthermore, for metallized gel droplets, the stage of Al reaction is advanced.