DIY Heat pipe

I've been wanting to make my own evacuated tube solar heater ever since I saw how people on here have built great arrays out of recycled material. But while reading up on them i saw that many people are using heat pipes for more efficient collection. So naturally the question became how hard is it to make a heat pipe?

Searching through the net I found a few place where people had tried to make their own heat pipes and and detailed the trial and errors they had. The concept and parts list seemed simple enough so i thought i would give it a shot.


WARNING: uses flammable chemicals and gasses.

Step 1 Get your materials

You are going to need (prices from Lowes)

1 - 1/2" x 24" copper pipe ($5.63)
1 - 1/2" copper end cap (10 pack $6.03)
1- 1/2" to 1" copper expander  ($5.11)
1- 1" copper end cap ($2.74)
1 - Teaspoon Acetone (comes on quarts $6.98)
1 - Torch (propane or mapp or whatever gas you prefer, already had)
1 - Tin of Solder flux ($2.94)
1 - Flux brush (sold in pack of 5 $1.58)
1 - spool of solder (1lb spool $21.91)

Comments

[foreverdisturbed]

Hello, I worked for Thermacore Inc. For 18 years making heat pipes and thermosiphones. Thermosiphones work gravity aided and can be made with water, methanol or acetone as a working fluid and are usually used for high power/heat applications. A heat pipe is not gravity aided and is usually always uses water as a working fluid and is for low power/heat applications. Thermosiphons can usually be made by a novice but, still needs to be done right to work properly for instance do not use solder use braze and you should braze with hydrogen and oygen so you don't need to use flux. Flux would be a contaminate and will off gas causing you thermosiphon to eventualy fail. Solder will cause the same problem. You need to use OFHC (oxygen free) Copper tube and caps. Your pipe needs to be very clean of any oils or grime inside this will also contaminate and offgas. When you process you thermosiphon it needs to be under a vacumme while processing and while sealing it. To do this add a small filltube to the top end of your pipe and then heat the bottom until you start to see fluid comming out and the top of the pipe is as hot as the bottom then you can use a modified wire cutter with the sharp edges filed rounded. Use the cutter to pinch the fill tube closed this should give you a leak tight seal. This is called a cold weld. After it is sealed and the pipe is still hot you can put a piece of glass or mirror above the fill tube to see if it leaks. If it leakes but is still hot you can just keep pinching it closed till you get it sealed. There is a special tool for this but, it is very expensive. The smaller diameter the fill tube is the easyer it will be to seal. 1/16" fill tube would be best but, no larger than 1/8" also heat up the fill tube red hot prior to processing that way the fill tube will be softer and easyer to seal. Hope this helps you or ntone else trying to make a thermosiphon. If you have any questions you can e-mail me at [e-mail]

[jcinman]

i would recommend brazing the joints if possible, some solders will get soft at the heat these can reach.

[Unsafe At Any Speed]

Looks good!
I think this would actually be called a "Thermo-siphon" since it has no wick inside and relies on gravity to return the condensate back to the hot end of the tube.

[jcinman]

thermo siphon is for liquids. this is a phase change that drives the movement, if you have phase change in a thermo siphon system it will cause vapor lock.

[HangdogBob]

Dteck, have you had any chance to use this, and how did you use it, and how well did it work? We'd like to hear more about this; looking forward to more info from you. Thanks.

[sam D]

What do you do with these?

[Dream Dragon]

Nice project and you helped me track down something I saw on TV ages ago that's been bugging me ever since. (Oil pipes on Permafrost)

I look forward to some testing and hope it works for you.

[Kiteman]

Good project!

[iPodGuy]

I hope you finish soon! I'm really interested in this one.