TCaldwell said:nofo, maybee something like this would be a little more potent than the turbulators in the eko, www.hpac.com. compact efficient heat transfer.
I'm getting turbulators made, and trying to get a quote from Zenon as well.
This design is great - I considered inserts that would have a similar effect, and be thermally coupled to the tubing walls. I think cleaning the fly ash would be a challenge.
Here's a photo - the page seems to change and didn't have the article when I looked at it.