I did not use a thermometer for this, I just wanted to get an initial idea of how the gel behaves when being heated.
notes to keep in your mind:
There are three goals, First is that heat needs to spread so the warming effects on the iv bag are as even as possible. Second, The sleeve needs to retain more heat for 30-45 minutes than needed to keep a 1000 cc IV bag warm at 100 degrees F. Lastly the gel bead to water ratio needs to be as such that it does not cause heat and time to be wasted warming the thermal mass before it can be used with the IV bag.
-My initial hypothesis that using gel in a cover would both retain heat and reduce the transfer was clearly correct. However it worked much batter than expected which is problematic. ( more on that later)
-Water beads are cheaper and easier that making other gels from scratch
-the size of the beads can be broken down in a blender if needed, but I think that will be too much heat flow restriction.
-The two 30 watt heaters were able to get all the fluids up to temperature and beyond in about 15 minutes, so I feel good about using them in a bag heater.
Cons- A maximum amount of water beads in a volume with the rest filled with water certainly works excellent for heat retention however it negates heat transfer so much that the volume does not heat evenly. That being said I was testing a volume of water beads about 2 liters, which no doubt if more than twice what I will actually end up using in the gel sleeve prototype.
Adjustments- I need to do another heat transfer capability test that is more realistic using the actual material I intend to use for the bag and do another test.