R&D project aims to optimise efficiency of fuel cells

Technology News |
By Christoph Hammerschmidt

The blower will be based on the so-called media gap motor developed by G+L innotec GmbH (Laupheim, Germany). The company is coordinating the research project; other partners are the Zentrum für BrennstoffzellenTechnik GmbH from Duisburg and the Institute for Fluid Dynamics (TFD) at Leibniz University of Hannover. “Hydrogen-based fuel cell technology is important for electrification in the mobility sector, especially for commercial vehicles where range is a major factor,” says Philipp Nachtigal, group leader at the TFD.

In fuel cells, hydrogen is blown into the anode – but it is never completely consumed. Through recirculation, the unused hydrogen is not wasted, but can be reintroduced. Currently, simple jet pumps are used for recirculation, but they do not work efficiently at every operating point: Especially in start-stop scenarios – i.e. during frequent starting and braking, for example in city traffic – a lot of hydrogen is consumed. “In contrast, the recirculation blower that we are developing on the basis of the media gap motor can always be switched on if the jet pump does not provide sufficient power or the fuel cell has to be flushed,” explains Nachtigal.

The researchers expect several advantages from this: First, the hydrogen is hermetically encapsulated in the new recirculation blower and transported without dynamic seals. “This is a significant gain in terms of safety technology and cost-effective in production,” says Christoph Klunker, product manager in the Business Development department of G+L innotec. Secondly, the hydrogen flows through the media gap motor and cools it – this increases the efficiency of the drive. Thirdly, the anode circuit can be precisely controlled load-dependently, which reduces hydrogen consumption. And fourthly, nitrogen and moisture which enter the anode circuit through the membrane of the fuel cell are reliably extracted from the fuel cell stack – regardless of how much power is drawn off. This should increase the service life of the fuel cell, says Klunker.

The TDH is primarily contributing its know-how in the field of turbomachinery design using numerical flow simulation: The main task of the TFD is the fluid mechanical design of the anode circuit. In addition, they functionally integrate the water separator necessary for operation into the recirculation fan.

The project “REZEBT – Recirculation Blower Development in Fuel Cell Technology” has been running since April 2020 for two years and is funded by the German Federation of Industrial Research Associations “Otto von Guericke” e.V. (AiF). The three project partners aim to complete the development of the recirculation blower by 2022.

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