Mortimer Posted March 30, 2011 Share Posted March 30, 2011 Hello all, I'm rebuilding a forge in southern England and wondered if I can harness any of the wasted forge heat to generate a small amount of electricity to run some low voltage lighting. Has anyone installed a small vertical steam turbine or hot air turbine in their forge flue or even a horizontal stirling engine over the flue entrance? I do not have any power in the forge and spend enough on coke only to see most of its energy go up in smoke...I know of one chap that has a gravitational operated heating system warming his second floor in winter but that about it. I know large steam boilers require certificates but I'm not planning on shoving a traction engine up the flue..... Any ideas would be most welcome, cheers.Mort. Quote Link to comment Share on other sites More sharing options...
macbruce Posted March 31, 2011 Share Posted March 31, 2011 Unless you run the forge for say 8 hrs at a run I would think wind power would be more efficient .........If the flue is drawing well don't tinker with it..........:D Quote Link to comment Share on other sites More sharing options...
Jreed Posted March 31, 2011 Share Posted March 31, 2011 Have you thought of solar? You can run the lights off of a car battery that is recharged with a small solar panel. Quote Link to comment Share on other sites More sharing options...
arftist Posted March 31, 2011 Share Posted March 31, 2011 Most of the stirling engine sites I used to visit are in Europe, and are now blocked to me. I don't know if this is my ISP or some business/political thing. There are successfull stirling engines, you will likely have better luck researching them than I have. In particular, there are a couple german models, not cheap by any means though. The other option for waste forge heat would be thermo-electric generators, or TEGs. They are reliable, relativly easy to install, much cheaper than a stirling engine, but still not cheap. You should be able to google TEDs and find manufacturers. MIT, here in Mass has made some dramatic breakthroughs in TEG efficiency in the last few years, don't know whether they have hit the market yet. Quote Link to comment Share on other sites More sharing options...
Mortimer Posted March 31, 2011 Author Share Posted March 31, 2011 Thanks for the swift input guys, most appreciated. The forge is in a deep, wooded valley and so wind and solar would not be efficient to any degree. I like the TEG idea and will look into having a TEG lined flue maybe....Cheers, Mort. Quote Link to comment Share on other sites More sharing options...
Glenn Posted March 31, 2011 Share Posted March 31, 2011 While conducting experiments with heat exchangers on the chimney of a normally aspirated wood stove, I found that there is indeed a limit to the amount of heat you can extract. The limit point was reached when the chimney stopped drawing (read no draft). I have numbers for the temperature of the exhaust, vs the surface area of the heat exchanger, vs type of fuel, etc etc, (for my setup) but the bottom line is it was necessary to waste some heat in order to get the fire to burn. I can also tell you the size and shape of all components should (must) be considered. I also found that you can not just scale up and get proportional results. Quote Link to comment Share on other sites More sharing options...
Pat Roy Posted April 20, 2011 Share Posted April 20, 2011 Remember, the chimney effect requires a temperature differential between the flue gases and the ambient air. Take that away and you will have no flow. Quote Link to comment Share on other sites More sharing options...
NeatGuy Posted April 20, 2011 Share Posted April 20, 2011 Why not use the waste heat to pre-heat the air blast for you forge making it more efficient ? brad Quote Link to comment Share on other sites More sharing options...
Pat Roy Posted April 21, 2011 Share Posted April 21, 2011 Pre-heating your blast air wouldn't make it more efficient. The hot air is less dense, requiring more CFMs to deliver the same amount of oxygen to the fire. The fire doesn't care if the air is hot or cool it just wants the oxygen component. Quote Link to comment Share on other sites More sharing options...
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