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Project REZEBT

G+L innotec receives government funding for development of a new fuel cell technology

Recirulation blower with media gap motor

Recirulation blower with media gap motor

Schematic diagram of PEM fuel cell with auxiliary units

In the near future, we want to use our Media Gap Motor (MGM) not only for the electrical assistance of turbochargers for combustion engines, but also for hydrogen applications.

In a joint project "Recirculation blower development for the fuel cell technology" (REZEBT), we will develop and optimize together with the Institute of Turbomachinery and Fluid Dynamics (TFD) at Leibniz University Hanover (LUH) and The hydrogen and fuel cell center ZBT GmbH, Duisburg a complete active anode recirculation of a Proton Exchange Membrane Fuel Cells (PEMFC). The Federal Ministry of Economics and Energy (BMWi) is funding the project as part of the "Central Innovation Program for Medium-Sized Businesses (ZIM)".

The project is limited in time and ends in 2022. G+L innotec is in charge of the project management and will develop, design and implement a cost-efficient and functionally reliable recirculation blower based on the MGM.

Conventional electric motors have the smallest possible gap between magnet and coils (magnet and rotor). Instead, the MGM offers a large gap to transport the medium directly through the motor and thus is able to cool it at the same time from inside. This design principle bestows the MGM an exceptionally high efficiency at high speeds and will hereby optimize the efficiency of the fuel cell and significantly extend its life-time.

The fuel cell converts hydrogen into electrical power and water. It consists of two parts: an anode and a cathode, separated by a membrane. Hydrogen is injected at the anode. The hydrogen releases its electrons and travels as a positively charged hydrogen atoms (H+) through the membrane to the cathode, where it merges with oxygen (O2) to form water (H2O). Power is generated by the electrons, which are drawn from the anode to the cathode. Water is thus the only emission of the fuel cell.

The hydrogen that flows from the tank to the anode is not always completely converted into energy. Furthermore Nitrogen and water appear in the anode. Both have to be blown out of the fuel cell to make room for the hydrogen, to allow an efficient reaction, or to prevent damages of the sensitive membrane (frost protection, life-time). For this reason, a circuit is installed on the anode, which on the one hand recirculates the unused hydrogen back to the anode to use it completely, and on the other hand to blow the nitrogen and excess water out of the cell.

Up to now, simple jet pumps that drive a circulation system have usually been used for this purpose. However, these only work efficiently in the nominal range, i.e. usually only under full load. In start-stop applications, therefore, more hydrogen is consumed than would be necessary to generate electricity. In contrast, the recirculation fan based on the MGM can always be switched on if the jet pump does not provide sufficient power or the fuel cell has to be blown free. This solution offers several decisive advantages:

  1. the hydrogen in the recirculation blower based on the media gap is hermetically encapsulated and does not require any dynamic seals. This is not only a significant gain in terms of safety, but also the reduction manufacturing costs.
  2. the hydrogen cools the motor from the inside and can increase the efficiency of the recirculation blower because magnetic and iron losses are greatly minimized.
  3. the recirculation circuit can be controlled precisely and in accordance with the power requirement, which reduces the hydrogen consumption of the fuel cell.
  4. nitrogen and moisture can be reliably extracted. The life-time of the fuel cell is thus increased.
  5. conventional pump solutions have disadvantages due to their design, which can only be avoided by additional investment and costly work-arounds in the anode circuit.

Even though this project focuses on the recirculation blower, the MGM can also act as a highly efficient electrical compressor at the other side of the fuel cell to blow air into the cathode and water out.

Here our press release.