Yah. The water was at a rolling boil (212 degrees) when the microwave stopped, but measured fairly consistently at 200 when I put the probe into the bag, so there was an almost immediate 12 degree loss. The recording of both time and temperature didn't begin until the probe was put in so we can't really say that its half of the reported loss. We could say that 1/3 of the total temperature loss from boiling occurred in the time between opening the microwave door to inserting the probe, but we didn't measure the time it took to do that.Mophead wrote:
Good point about the starting temp. Water cools faster the hotter it is... if that makes sense. So the curve of cooling water is going to look like a negative exponent. You wouldn't be at 212 for very long, maybe not even by the time you poured into the bag. But your cook temp will average much higher than 160. If you noticed by the time the water was out of the microwave to the time you got starting temp you are at about a 15 degree loss (assuming the water was at 212 which I think is reasonable) That's about half the loss experienced during the 15min cook time and maybe happened in 2 minutes? I like how you did your tests, it has me thinking about this subject differently now.
FWIW The more I read and think about this, especially the refrigerator test, I wonder if reflectix is even a suitable material for this task if one were to go with a coozie. Is a food bag really losing heat through radiant loss (reflectix is a radiant barrier) or could it be conductive loss from the bag setting on the cold shelf of the fridge? If a food bag is really losing its heat through radiant loss then a space blanket with an air gap from the bag should work equally as well.
Whatever contribution to heat loss comes from convection is mitigated by the design of the bag as the contents of the bag are never in contact with any surface other than the plastic of the bag itself. The bowl sits about an inch from the bottom of the bag.
When I test the heat loss with the cozy I'm going to compare that to covering the bag with at least one other thing that I normally bring along in my pack: a bandanna, shemagh, shirt, etc., to see if they are comparable in effectiveness to the reflectix. I suspect that the difference between throwing something like your top quilt or the skivvies you're going to wear the next day over the bag will be at least as effective as the cozy, IF the cozy makes any appreciable difference at all.