Hello,
I still see this plan, having taken a little closer look at the information, as a bit of an uninformed adaptation of the traditional idea of the radiant heater, with room for a better use of the fuel by a top down combustion instead of from underneath which is sucking the cold outside air directly into the burn chamber, and then, channeling residual gasses back through the burn chamber for a second burn instead of around it, and then simply sealing the whole thing off once combustion ceases. And these barrels seem an inadequate improvisation destined to burn up themselves with even moderate use.
Greetings,
Don Wagstaff