I find it interesting that 100W for ~120 seconds is ~0.3kcal which for a 100ml cup is ~3C. They are right at the limit of power to flow rate. Much faster flow and presumably the cavitation wouldn't "brew" enough, while much slower and it would warm up the coffee noticeably. I'm doubtful the frequency matters much if the cavitation is what is causing the mixing since those are just bubbles emerging and popping, but the efficiency of coupling from ultrasonic wand to liquid could change a lot.
Since you could presumably put 2 of these in parallel and have 2x100ml cups in 2min with 200W without changing the recipe (or 1 cup in half the time), this seems pretty scalable with increased cost and area.
Unagitated cold brew is in the 10hour region, but with agitation/pump through it seems like you can do 8 cups in 20min which is almost as fast as the cavitation method. I suspect the grind size starts having really big effects here.
Since you could presumably put 2 of these in parallel and have 2x100ml cups in 2min with 200W without changing the recipe (or 1 cup in half the time), this seems pretty scalable with increased cost and area.
Unagitated cold brew is in the 10hour region, but with agitation/pump through it seems like you can do 8 cups in 20min which is almost as fast as the cavitation method. I suspect the grind size starts having really big effects here.
https://instantpot.com/products/instant-cold-brewer