Hyfindr Tech Talk # 2 – SOEC/SOFC Heat Exchangers explained

Hyfindr Tech Talk #2 SOFC Heat Exchangers

In this video, Steven Oji (Hyfindr) welcomes Stephan Pflugfelder (smk), an expert in laser welding and heat exchangers, to discuss the technology behind the hydrogen economy. Stephan brings an SOFC heat exchanger for SOFC (Solid Oxide Fuel Cell) applications, which are known for their high efficiency in producing power from hydrogen. SOFC technology operates at temperatures of around 700-900 degrees Celsius, requiring specialized materials and components to function effectively. The heat exchanger that Stephan brought is specifically designed to handle these high level requirements.

Learn about SOEC/SOFC Heat Exchangers and the related System Design

SOFC technology is distinguished from other fuel cell systems, such as PEM (Proton Exchange Membrane) and AFC (Alkaline Fuel Cell), by the way it operates and the higher efficiency of the process.


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The cell can either be used for power generation (SOFC) or hydrogen production (SOEC). Stephan presents a diagram to help illustrate the SOFC process, showing the air and hydrogen cycles including the corresponding heat exchangers. Hydrogen and oxygen react with each other producing current, while the heat of the hot gases from the cathode and anode is recuperated into the SOFC cycle through the use of heat exchangers.

Stephan explains that it is typical to have two SOFC heat exchangers linked to the stack, one for air and one for fuel side. The amount can vary depending on the needs of the OEM (Original Equipment Manufacturer). In SOFC operation the fuel heat exchanger, like the one Stephan brought, is smaller in volume compared to the air heat exchanger. The gases entering the heat exchangers have temperatures of around 800 degrees Celsius, and the heat exchangers are able to transfer this heat with high efficiency (>90%) to the fresh gases entering the stack. Thereby the used gases are cooled down to around 150-200 degrees Celsius.

The design of the heat exchangers must take into account thermomechanical stress, as the materials will expand and contract with changes in temperature. Laser welding is used to join the materials at low heat input to minimize stress in the materials, making the heat exchanger more durable. Every unit is thoroughly tested before delivery. Validation is performed based on customer specifications to ensure proper operation over lifetime.

Stephan also emphasizes the importance of safety in the design of the heat exchangers, as they are intended for full-time, stationary operation. smk uses thicker heat transferring plates to make the heat exchanger more robust. The stack is typically has a higher sensitivity against thermomechanical stress, therefore the heat exchangers can easily meet the heating up and cooling down requirements of the OEM.

Overall, the SOFC/SOEC technology has the advantage of high efficiency and the ability to operate 24/7, making it a promising solution for producing power and hydrogen.

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If you like the video, please also subscribe to our new Hyfindr Youtube Channel. We will launch Hyfindr Tech Talks in January – a new format that is specifically designed for engineers who are interesed in the hydrogen economy!

Steven is a fuel cell system designer and he will deep-dive into the technology that makes the hydrogen economy work with real experts. We hope you will like the new format.

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