These are some incredible resources you've posted, I am very happy to see that you're approaching this from a research point of view. I'm curious what @Atom, @adam, & @yusuf.khan.su think about this setup compared to traditional High Pressure Aeroponics.
Great looking growing chamber, did you build that? Is that a PVC material or what are you using?
I would be happy to help you with your code, what are the aspects you're trying to actuate? I'm not super familiar with the brain_box but am interested to see where you're at with the software. The MVP right now actuates a 120V plug to control the exhaust fan that is the thermostat, this could be adapted to exhaust a greenhouse (I plan to use the code for that exact purpose). Also, depending on how you build your chiller you could use the exact same software & hardware to cool the water as well as the air (temp sensor, and 120V relay actuation).
I'm curious if it matters how long the fog travels through the tube prior to reaching the roots. Does it condensate heavily on the sides? Also, with HPA you dose in small increments every few minutes, do you plan to do similar or have it always fogging?
I understand that your water temperature has increased, but what I am wondering is the temperature of the mist itself. Something that really hasn't been researched probably because it is generally the same number with hydroponics is the difference between root temp, and water temp, perhaps water temp is irrelevant and what really matters is just keeping the foggy air cool. In the past, by just putting a 12V fan on a reservoir (this was 120 Gal) it dropped the water temp just by evaporative cooling by 6 degrees consistently as opposed to when it was off. That being said, I'm amazed that you're seeing a 10C increase in temp from the fogger, that is definitely substantial (and 32C is too hot for hydroponics at least).
Love the commitment to keeping things open source. Let me know how I can help with the code. I definitely think it will meet your needs, and provide a great starting block for someone who really isn't familiar with software dev to get in and add on some more sensors/relay actuation controls within just a few days.