Investigation and description of the solubility behaviour of paraffinic diesel fuels

The energy transition in the transport sector requires a significant increase in the proportion of alternative and innovative drives and fuels. In the area of diesel fuels, the use of CO2-neutral fuel components such as hydrogenated vegetable oils is an option. With increasing admixture to conventional diesel, their paraffinic structure influences important fuel properties. As part of the project, studies were carried out with paraffin-rich fuels on water absorption and turbidity behaviour as well as crystallization at low temperatures. In accordance with the lower polarity of paraffinic fuel components, they have a lower water absorption capacity. However, this property is not directly linked to the formation of emulsions or turbidity. A correlation of the composition with the formation of turbidity due to free water could not be proven within the scope of the project. Overall, the turbidity behavior of the fossil and paraffinic fuels investigated was neither uniform nor systematic. The nephelometric turbidity measurement with a spectrophotometer proved to be well suited and enables better differentiation compared to the ASTM methods commonly used in the industry. A microscopy setup was developed for investigating the crystallization properties, with which it was possible to work at temperatures down to < -15°C. The kerosene crystals formed at these temperatures could be visualized and measured using the polarization unit. Here it could be seen that long-chain kerosenes form larger crystals than isomerized kerosenes. The effect of additives to improve the low-temperature properties was also demonstrated. It should also be mentioned here that the additives should be tailored to the kerosene structure of the fuels in particular in order to achieve the desired improvements.

The IGF project (21666 N) of the research association DGMK Deutsche Wissenschaftliche Gesellschaft für nachhaltige Energieträger, Mobilität und Kohlenstoffkreisläufe e.V., Große Elbstraße 131, 22767 Hamburg, Germany, was funded by the Federal Ministry of Economics and Climate Protection via the AiF. Große Elbstraße 131, 22767 Hamburg, was funded by the Federal Ministry of Economics and Climate Protection via the AiF as part of the program for the promotion of joint industrial research (IGF) on the basis of a resolution of the German Bundestag.