Phase-change waste heat recovery device (customizable)

This is a prototype/experiment for a phase-change material thermal mass structure for fitting around a stove pipe (or other pipe) to recover and store waste heat.

The PCM chamber is constructed such that it acts somewhat like a thermal diode to deliver heat into the room, but resist back-flow back out the pipe. (Or, at least, that's the goal of the experiment.)

I have not yet done any testing with this. If you do, or if you have any suggestions, let me know!