FVV strengthens hydrogen research

The use of renewable ‘green‘ hydrogen as an energy carrier is not limited to fuel cells. It can also be used directly in combustion engines and gas turbines. However, the chemical properties of hydrogen differ significantly from those that characterise fossil fuels. Therefore, technical adaptation or redesign of internal combustion engines, turbomachinery and the related combustion processes is necessary. With a dozen new research projects, the FVV (Forschungsvereinigung Verbrennungskraftmaschinen) wants to create the scientific basis of advanced combustion technologies for sustainable transport and mobility. A project that will be performed at the Institute for Internal Combustion Engines (IFKM) at the Karlsruhe Institute of Technology (KIT) is exemplary for this. It will investigate the potential of future combustion processes using heavy commercial vehicles as an example. The hydrogen is first blown into the engine's intake manifold and then, after the engine has been modified, directly into the cylinder. This allows the influence of mixture formation on hydrogen combustion to be investigated. The researchers intend to place particular emphasis on the conflict of objectives between high power density and uncontrolled self-ignition of the mixture. In addition, combustion is to be made as efficient and as low-polluting as possible. Prof. Dr. Thomas Koch, director of the research institute, sees hydrogen engines as a great opportunity: "We are capitalising on the existing know-how we already have in Germany and are continuously developing it further - not least through our work for the FVV".

Hydrogen engines are seen as having great potential, especially in commercial vehicles for on road and off road operation. But what does the ideal hydrogen powertrain for a heavy-duty truck or an excavator look like? This question is to be answered by another major research project. Cold combustion in the fuel cell as well as hydrogen combustion in the piston engine are potential technology options, but have different advantages and disadvantages depending on the application and duty cycle. Within the project the technical options for different applications and cycles will be simulated and an evaluation matrix will be created. On this basis, future technology roadmaps for commercial vehicle powertrains will be developed and the technical challenges of the new concepts will be identified. In addition, the combustion behaviour of engines with direct hydrogen injection will be investigated in detail and corresponding three-dimensional simulation models will be created. The FVV is thus laying the foundations for the rapid industrialisation of hydrogen CV powertrains.

In the shipping industry, the introduction of carbon neutral or carbon free energy sources poses a particular challenge, as very high energy volumes and storage densities are required in long-distance transport. For this reason, the industry is intensively discussing the further processing of renewable hydrogen into ammonia. Liquid hydrogen, on the other hand, cannot be stored permanently due to its low boiling point and is therefore less suitable for transport over long distances. Ammonia, which also serves as the starting material for hydrogen, is better suited for this purpose. At ambient temperature, NH₃ is already liquid at a pressure of more than 9 bar and is therefore easy to store and transport. However, there are still many open questions regarding its use in large engines. For example, the ignition energy is about 50 times higher than that of methane. In a new project, the FVV therefore intends to investigate both the fundamental suitability of ammonia as a fuel of the future and the boundary conditions for engine combustion. At the same time, a life-cycle analysis will be carried out to compare ammonia with other renewable fuels.

As energy carriers for sustainable air transport, primarily electricity-based liquid fuels are being discussed, but more recently also the direct use of hydrogen. Like all other combustion engines, jet turbines must be adapted to the new fuel, too. "At the FVV, we benefit from the fact that research on stationary gas turbines and aero engines is closely networked," says Dr Dirk Hilberg, Technology Manager at Rolls-Royce Germany and Deputy Head of the FVV's Scientific Advisory Committee. Projects on the influence of hydrogen admixture have already been carried out in the past. "I am convinced that hydrogen and other alternative fuels will decisively determine turbine research in the future", says Hilberg.

The fuel cell works with hydrogen anyway. Since 2017 the FVV has been concentrating all fuel cell activities in a specific planning group. This group can now demonstrate initial successes: The "generic fuel cell stack", a pioneering project, was completed at the end of September. For the first time, a concept for a manufacturer-neutral test specimen is available. Such a stack, comparable to the single-cylinder units used in engine research, is the basis for pre-competitive cooperation on components and systems, which is of particular benefit to the medium-sized supplier industry. In a follow-up project, a real test device is now to be created on the basis of the concept.

However, the FVV does not focus exclusively on hydrogen-powered energy converters, but also researches the operation of combustion engines with other renewable energy sources. Increasing the efficiency of combustion engines, for example through hybrid concepts, also plays an important role in the association’s research portfolio. "We always look at the complete life-cycle balance of energy sources, storage systems and converters," says FVV Managing Director Dietmar Goericke. "A holistic comparison of the energy efficiency of different powertrain alternatives along the entire value chain is also important to us. The transformation of the energy and transport system needs a reliable scientific basis for the evaluation of all technologies that meet the climate target".

Source and photo: FVV