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 drive systems and fuels. The German government's energy concept relies on the rapid market introduction and spread of electric vehicles (battery vehicles and fuel cell vehicles) on the one hand and alternative, advanced renewable fuels on the other. In the course of implementing the Renewable Energy Directive II (RED II), the EU member states are obliged to continuously increase the share of renewable energies in mobility. For the transport sector, a share of renewable energies of at least 14% is required for 2030. According to the Fuel Quality Directive (FQD) Article 7a, the target of 6% less greenhouse gas emissions already applies for the year 2020. This means that the proportion of renewable components will increase, especially in diesel fuel, and will also grow continuously over the next few years. The focus here is on paraffinic fuel components from various sources and produced using different processes. Examples include hydrogenated vegetable oils (HVO) and products of Fischer-Tropsch synthesis (FTS products). In the case of HVO and FTS products, these are chemically paraffinic components which are characterised, among other things, by outstanding application properties (e.g. high ignition readiness, high energy density, etc.) especially for the middle distillate range. The increase in n-/iso-paraffinic components in diesel fuel in particular will lead to a noticeable decrease in the aromatics content and thus the solubility of the fuels in the future.

The aim of the project is a structured investigation and the creation of basic knowledge on the influence of higher proportions of n-paraffinic and iso-paraffinic components (or lower proportions of aromatics) in diesel fuels on key fuel properties. The focus of the project is on investigations of

1) Water absorption and turbidity behaviour

2) Crystallization of paraffinic components

3) Phase stability and dissolving power

In particular, the special requirements of logistics, such as temperature changes and mixing of different components, as well as seasonal differences (summer, winter quality) and interactions with the biodiesel content commonly found in diesel fuel (up to 7%) will be taken into account. In addition to practical and analytical laboratory tests on the specified issues, the evaluation of an alternative fuel parameter to describe the solubility capacity will also be carried out.

The project has been completed. The results are documented in DGMK Research Report 846.