This Penn student invention saves energy, could help refugees https://www.google.com/url?hl=en&q=...626000&usg=AFQjCNFPnCHiSzRRaX5CJdnQV3vlE8BHnA
Good so long as it works but it still seems like it would impede the flow of gasses to to up the chimney. Once the gravel got hot you would not lose much heat but if the stove needed to be fired up often I would question the value. After all, let us not forget the magic heater that was "invented" back in the 70's and so many thought it a great invention...until the creosote problems cropped up big time. Heat still needs to flow up the chimney, no matter what is burning. Removing that heat to heat gravel or any other object makes me a bit suspect of it. Still, I wish them well.
Great Idea Just basically a thermal mass in a tube. Now I don't think I wanna do that in terms of how malleable metals are with heat and weight. Its a good idea dont get me wrong but how do the coefficients work with weights like rock then with metal and heat potential and displacement or emissivity? If they built a way to allow the stove to heat the rock but let the exhaust out, think honeycomb.
