Common rail fuel-water emulsion

As part of this project, a fuel system suitable for delivering fuel-water emulsions in common-rail systems was developed, along with two solutions for injectors capable of injecting fuel-water emulsions into diesel engines using the common-rail method.

A Venturi mixer—which is simple in design and requires little maintenance—is used as the mixing device; in this mixer, a fuel jet serves to form an emulsion with the water, which is also under pressure. The design was carried out using 1D and 3D modeling tools. Tests on the injection test bench and on the engine confirmed the high quality of the resulting emulsion.

Furthermore, as part of the project, a common-rail injector was modified in terms of both geometry and materials in the pilot valve, which is particularly susceptible to cavitation wear. As a result, its service life with an externally mixed fuel-water emulsion was increased several-fold without any failures. In engine tests, this injector was operated with water ratios of up to 60%, demonstrating the enormous potential for reducing nitrogen oxide and particulate emissions.

The findings led to the development of another injector in which the emulsion is generated inside the injector and the vulnerable pilot valve is supplied with pure diesel fuel. This design offers the greatest potential for operation with a fuel-water emulsion and will also provide advantages during transient engine operation. A prototype demonstrated its basic functionality on the injection test bench.