A Method for Determining the Bunsen Coefficient of Bio-Hybrid Fuels

Since the amount of dissolved gas in fuels is an important quantity for the description of aeration in injection nozzles, this paper presents Bunsen absorption coefficients for different conventional and bio-hybrid fuels and their effect on nozzle flow phenomena. Bio-hybrid fuels can be produced both on the basis of biomass and with the help of regeneratively generated electrical energy. In contrast to previous work, the Bunsen coefficient was determined for a wide pressure range from approximately 10 MPa to 32.5 MPa. In fact, some of the fuels considered here were never before objects of investigation in terms of their solubility properties. In this work, large differences regarding the Bunsen absorption coefficient between a conventional fuel and a bio-hybrid fuel were observed. For determining the solubility of the fuels, a manometric-volumetric method was used. Based on the measurement results, coefficients for the Krichevsky-Kasarnovsky equation, which describes the pressure dependency of the solubility, were calculated. The mere knowledge of the Bunsen absorption coefficient does not yet allow a statement about the relationship between the amount of dissolved gas and the phenomena of aeration in injection nozzles. In order to investigate this relationship more in detail, a conventional and multiple bio-hybrid fuels were enriched with predefined amounts of nitrogen. Subsequently, the flow within a glass nozzle was observed and recorded with an ultra-high-speed camera to capture the cavitation phenomena. The results show a significant impact of dissolved gas content on cavitation in the injection nozzle.