@juul this project is kind of like a NASA mission, in that it's a success once it clocks a few hours of science on the surface of mars / temperature consistently lower than the propane fridge. Beyond that, 0-10C is a fairly arbitrary goal I coded into the software, if it continues in that range, great. Of course it would need to be consistently 0-5C for this to be generally acceptable by modern fridge standards.
Glycerol seems to run around $10/gallon in bulk, may give it a try once I get a better idea of the target temp. https://www.bulkapothecary.com/raw-ingredients/other-ingredients-and-chemicals/glycerin/