Heat Exchanger in a stove

There are many things to consider here. I think there are various steam cleaners that have copper coils as their heat exchange surface, but they are filled with water/steam at temperatures much lower than the melting point of copper. Air-filled tubes might be vulnerable to melting, depending on the flame temperature where it impinges on the tubes.

Encasing the tubes decreases the area that can transmit thermal flux to the tubes. This will protect the tubes but will decrease the efficiency. Overcooling of flue gases will condense acids onto the tubes, risking corrosion. Be aware that there is quite a balancing act that must be done.

http://www.google.com/#hl=en&source=hp&q=stove+%2B%22water+heating%22&aq=f&aqi=g-m1&oq=&fp=cbc2f75bf9d43a8f

Hi Theo,

Several thoughts come to mind for your water heating project. Combined Heat & Power is always my preference. I have several videos listed in my Favorites about Wood Gasification that apply here. As matter of fact 1 video referenced below is about building a wood gasifier from propane tanks , so you might like it. A Woodgas cleaner section would use coiled copper tubing to exchange the heat with water inside copper tubing so, I know it works & long term as in years. The cleaning process cleans the gas so you can run a motor with it - like a generator. Join my facebook group If you need any further refferences, its noted below too.

Hope some of that helps you !

1st link:

http://www.youtube.com/user/GeorgiaAdobe#p/f/17/-cXzDGscKt4

Joe Woodall, Managing Partner

Georgia Adobe Rammed Earth & Renewable Energy

http://www.georgiaadobe.com

http://www.dopestcontrolyourself.com

http://www.facebook.com/georgiaadobejoewoodall

You don't have to use copper in the stove. Steel would probably be as good and resist to higher temperature. If rusting is a problem, Stainless could be used.

I suppose its finding the balence between copper and steel, bear in mind i dont have the facilities to bend steel thinker than 2 mil, so 1.2 mil is what i could get/could bend. Whereas with the copper i have, it is a 2.5 mil wall. Not sure what would be most durable, Stainless would be fantastic, but again i do not have equipment or know how to work with it.

Theo ,

SS would be a better animal but it is more expensive. Bending into coils is pretty easy with the copper , if its the thick walled you can add sand & pack it before bending to assure no kinks. Tap and wash it out after. Use a small dia log on some saw horses with a v notch & a younger strong back to turn the thing, with a pole bored through it, on one end.

Keep us updated !

Joe

I have several suggestions and ideas, but I need to know what type of fuel you are using and are your temperature; is it in deg. C or F?

The copper will work as long as you avoid condensation, direct flame and over heating.

30 mil is about 0.75 mm. 3 mil is just 75 micrometers. Is this understanding correct? Nothing can be done with such dimensions.

Here's a drawing we use to discribe the heat transfer process to our clients. Maybe it will be of help to you too.