Tackling battery fires in confined spaces using potassium aerosol

[nsarifds]

Hello everyone,

I would like to model the suppression of a battery fire when the suppressant is a potassium aerosol. My issue is that the suppression mechanism is not the dilution of oxygen neither the cooling of the fire, rather the binding of free radicals to the potassium atoms towards the formation and deposition of solid KOH and K2CO3.

Would something like this be within the capabilities of FDS using multiple step reactions and potassium particles? Have you encountered anything similar in your experience? Are you familiar with any similar simulations or any literature that have used FDS? Can you think of a strategy to simplify the problem?

Also, bonus question, would this be the best suppression strategy for a battery fire, where the heat and fuel is being produced from inside the battery? Wouldn't the dilution of oxygen be a better candidate to ensure the fire cannot reignite, or is there an explosion issue arising in the small confined spaces this would be applied to?

Thank you in advance for your time, support and guidance!

[drjfloyd]

If you are looking to suppress something like a grid scale energy storage fire, not sure how viable of an approach this is. It isn't going to stop batteries currently undergoing thermal runaway. If the system discharged and there wasn't a fire, just the heat associated with the runaway, the particles may not decompose and they will settle out of the gas whihc could allow for delayed igniton. Similarly if there is a fire and it puts the fire out, but batteries are still undergoing thermal runaway you could have reigniton as particles settle out.

In pricniple you could do this with detailed kinetics. We have been playing a bit with this idea only for sodium bicarbonate with some limited success. We gave a talk on this at the 2023 FM Global Fire Modeling Workshop (https://github.com/fmglobal/firemodelingworkshop/blob/main/archive/2023/presentations/mcdermott-NIST-sodium-extinction.pdf).

This is very much a research problem that is going to take you a good deal of time and effort. Some of challenges will be:
-Determining an appropriate set of kinetics for your battery gas that includes the free radicals the exintguihser acts on
-Determining an appropriate set of kinetics for the interaction of the gasseous decomposition products of aerosol with the free radicals
-Determining an appropriate set of kinetics for decomposition of the aerosol
-Likely need to do this at DNS resolution (1 mm or less grid size) unless you can somehow get a set of kinetics to work at LES scale

[nsarifds]

Thank you for your time and information!

I am referring to a few hundreds of 18650 batteries, not grid scale energy storages. Does this make the approach more applicable?