Spiral Heat Exchanger Manufacture

[GiTS]

I'm not usually into the "green" thing, but an unrelated interest brought me to the topic of spiral heat exchangers and I also received some encouragement.

The idea is a small, low cost spiral heat exchanger for use in village sized water treatment, desalination, and for making showers "greener" by recycling heat.

In my mind I'm thinking a thin aluminum (about soda can thick) sheet coiled around two pipes then the ends are weld to the side to make the spiral shape. It's kept in that shape simply due to spring force. Thin stamped sheet metal or plastic end caps with a rubber gasket are clamped onto the spiral and attached with either metal wire (like a drum) or screwed together with long rods or hollow tubes. The pipe fittings are all on the faces.

I would like a design that is very cheap to automate with existing equipment. Thoughts? I know very little about the manufacturing process when it comes to relative costs. I know how to get quotes on molded plastic parts but not the metal working processes.

Any engineers out there know how this could be done? Is there a good manufacturing forum to send this inquiry to? Is there a no hassle way to get metal work quotes?

Many Thanks
-GiTS

 

[Bobbywhy]

GiTS, simple but effective heat exchangers occur in Nature. Owing to evolution this process has become efficient allowing many animals to successfully survive and propagate their genes onward. May I suggest some aspect of the countercurrent process may apply to your project?

"Countercurrent exchange is a mechanism occurring in nature and mimicked in industry and engineering, in which there is a crossover of some property, usually heat or some component, between two flowing bodies flowing in opposite directions to each other. The flowing bodies can be liquids, gases, or even solid powders, or any combination of those."
http://en.wikipedia.org/wiki/Countercurrent_exchange

Cheers,
Bobbywhy

 

[GiTS]

A spiral heat exchanger is a countercurrent flow type heat exchanger.


I should clarify for all readers
I am not designing a heat exchanger. I am only trying to match current manufcaturing processes with this type of heat exchanger to produce a small cheap version.

Spiral HEs currently are massive stainless steel vessels handwelded and used in chemical processing. They cost $10,000 and have flowrates of gallons per minute. I am looking to decrease the cost from $10,000 to $10 and the size down from 5' diameter to 6". The quality also goes down but consumers don't need stainless steel for shower water etc. That's the dream.

 

[parislad]

What sort of heat duty is required for your application in mind? Have you thought about doing any numerical modelling based on your design?

 

[GiTS]

parislad, I don't understand your question. It is a light duty application. Just water from shower drain or sinks.

I have not done any numerical modeling. I am not designing the heat exchanger, I am just trying to find ouut the manufacturing processes I should/could use.

 

[moemag]

Depends on what you are trying to do. High volume, figure out how to stamp it out of sheet metal. Look at the automotive world for this... try to find something that isn't a sheet metal part on a car and it will be a casting or plastic. Sheet metal solutions would be things such as radiators. Get a oil cooler radiator and confine it in simple box to which your heat will travel to your second fluid.

If you are looking for something that doesn't require as much tooling overhead... try tubing. I have built tons of heat exchangers out of coiled refrigeration copper tube. Pretty simple mfg process. Just make a mandrel (piece of tube) in a lathe, figure out the correct lead, and feed the tubing with the compound just like a thread. makes beautiful coils that can be fit into a larger piece of tube. Just fill the copper tube with sand or ice so the tube doesn't collapse.