2019 / Integrated mobility technologies

On the accelerator - but emission-free, please!

    Integrating the fuel-cell drive into the vehicle is an important task, so we can move forward in a more sustainable and environmentally-friendly way. At the same time the integration is also a great challenge.

    The facts are convincing: The availability of hydrogen is almost unlimited and regenerative energy sources can also be used for its extraction. In addition hydrogen can be easily stored and transported and is perhaps one of the most important energy carriers of the future. Dr. René van Doorn is a specialist for hydrogen and fuel-cells at PSW and together with his team supports vehicle manufacture in the integration and development of innovative hydrogen propulsion. On the one hand this is a task with technical depth and on the other, the conceptual vision requires that the framework conditions are demanding.

    Technological understanding and bureaucratic overview

    ‘Laws and regulations for high voltage and hydrogen safety, which are relevant for the approval of a fuel-cell vehicle vary from country to regions’, says René ‘therefore, country specific safety concepts must be developed.’ ‘We are researching the requirements for many different countries and document what we find in a database’. And it is more than just documentation. Above all the requirements must be conceptually implemented. An example: An EU regulation specifies that vehicle emissions must contain no more than four percent hydrogen. So far, so good. However, there is an operating state of the vehicle during which hydrogen is quickly discharged once every minute (this is called ‘flushing’) and the four percent limit must not be exceeded. How does this work? This is one of the many hundred brain teasers which the PSW team solves. ‘We come together and consider what a solution might look like. On the one side there are the colleagues, who have knowledge about how to handle hydrogen. On the other side there are the experts, who look at the legal situation and who have the know-how about the fuel-cell system’, explains the graduate chemist to the PSW team set up. ‘This way we bring together legal requirements, system requirements, system understanding and simulation. Here we live and work according to the latest development methods within the meaning of system engineering.’ But what is actually simulated there?

    Fuel cell at PSW

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    PSW is responsible for package topics in the cooling area of ​​the Audi Q5 HFC, a technology study by Audi.

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    Package and concept studies for fuel cell propulsion.

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    Commissioned the Audi h-tron and set up a separate department for fuel cell development.

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    Expansion of the commissioning and expansion of internal fuel cell development as well as investment in test benches.

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    The Audi h-tron quattro concept, the Audi concept vehicle for the development of the fuel cell drive.

    The operational strategy is decisive

    René has an example: ‘Due to the low operating temperature of the fuel-cells, the requirements for vehicle cooling are significantly higher than combustion engines. The fuel-cell drive can only be integrated when it is comprehensively considered together with the cooling. We have developed a separate simulation model for this purpose, the modular longitudinal dynamic simulation.’

    Within the scope of this simulation all dependencies can be calculated in the vehicle such as consumption, acceleration, range, rolling resistance, speeds and temperatures. ‘We simulate the nominal operating conditions and from this it is calculated how the fuel cells can be operated most efficiently,’ explains René. With the entire knowledge the PSW team paves the way to integration and supports the manufacturer in making the alternative suitable for the series. ‘The simulation environment has been designed in such a way that not only can a complete fuel-cell hybrid drive train be simulated, but the subsystems can be optimised as such. The simulation of other drive types can be carried out, such as pure battery mobility.

    Effective project objective

    Speaking of ‘fit’: If you want to make others fit, you’ll need to be on the ball. Erhard Dörr, head of project management gives a clear answer to this question: ‘We are more effective than the free market and manage to reach the targets of the topics in a few hours. This was first confirmed by an expansion of our assignment at Audi’s h-tron project. The key to our competence in technical questions: How do you succeed in integrating a large hydrogen tank into the car? How do I redesign a complete floor assembly? What affect does this then have on the crash behaviour? And so on.” The vehicle must function as a whole. Erhard: ‘In order for this to succeed, we have just the right people at the right points, who continually swap with each other. This way our projects meet their targets in terms of schedule, costs and quality.’

    ... and how will we drive in 20 years?

    With so much innovative strength the question remains about how fast the company can implement alternative drive systems,for instance in Germany. René’s view: ‘We will live for a long time with a mix of drive systems. But in 20 years there will be far fewer cars with combustion engines for many reasons. This is only due to the CO2 emissions. The world will drive electrically, in other words with batteries and fuel cells. But that’s still a long way off.’

    The traffic lights are still yellow

    The framework conditions with respect to fuel-cell drive are still difficult since there is no comprehensive service station infrastructure. There are currently around 100 service stations for hydrogen in Germany and if the born Hollander René van Doorn wants to drive to Italy on holiday with a car propelled by hydrogen, the small amount of filling stations on the route would surely prove to be a headache. Therefore, there is more reason for him to stick with his team and get the fuel-cell drive onto the road.

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