Growing up in the countryside in Sweden, I got used to several power outages a year due to snow, storms, lightning, etc. No water, no electricity and no heat for days, sometimes in the middle of winter, meant you had to huddle together to keep warm, get water from a local supply and eat cold food. A possible remedy for this annoyance is distributed energy generation. Solid Oxide Fuel Cell (SOFC) combined heat and power systems are independent of local weather conditions (unlike wind and solar systems) and provide a cleaner, quieter and more efficient alternative to traditional petrol generators. SOFC systems are used to power and heat/cool data centers, homes and stores across the globe, as well as for offshore and remote military applications. Power outage for a data center doesn’t only mean inconvenience and freezing indoor climate, it also means large financial losses due to downtime, so SOFC systems are often used to supply reliable power.
To support the movement towards cleaner and more efficient distributed energy we have made simulations of SOFC systems straightforward in STAR-CCM+® v12.02. You can now natively specify the required electrochemical reactions on the anode and cathode as well as the ion transported through the membrane, making it much easier than before to set up such calculations.
To understand how STAR-CCM+ can be used for SOFC calculations, consider the possible workflow shown below. First, you typically need to calibrate the electrochemical reaction rate parameters since reaction rates depend on anode and cathode material properties. To do this, a simplified test bench setup can be used, such as a button cell in this example. Calibration is then done, in this case with Optimate+ for a range of fuel qualities. The calibrated model is used for full stack calculations and ultimately design exploration.
So, how do you set up the electrochemistry for SOFC? Watch the two-minute video below to see the required steps for cathode and membrane.
The field functions mentioned in the video, required for electrochemical reaction parameters, are delivered with the button cell sample case shown above, available as a demo case on the Steve Portal.
For those among you who want to know more - what did we add in STAR-CCM+v12.02 to enable SOFC?
Electrochemical reactions with multicomponent gas/liquid species
Solid Ion Model
Before STAR-CCM+v12.02, only electrochemical species could be included in electrochemical reactions. Now, multicomponent gaseous or liquid species are also supported, which is crucial for SOFC as gaseous hydrogen and oxygen react through electrochemical reactions to form water. The picture below shows an example of this: in the cathode reaction the multicomponent gas species O2 (orange) reacts with an electron (e-, green) to form the solid ion species O-2 (blue). This O-2 needs to be transported through the solid membrane to the anode side to react with hydrogen, and the Solid Ion Model handles this transport.
Easy, right? With these new capabilities in STAR-CCM+, please go ahead and make the world a better place to live, with fewer power outages…
Interested in Fuel Cells? Join our Fuel Cell Applications group in the Technical Forum on the Steve Portal, to always get the latest news and tips.