DIY heatpipes - warming up. [2017-12-09]
Puns aside, this here is my first post so expect it to be thoroughly mediocre.
A couple of weeks ago i got quite interested in heatpipes, I can thank my overheating laptop for that.
Heatpipes as a whole are very interesting little things and getting one to work properly is not that easy. When making a heatpipe obtaining the materials is probably the easiest part, the hardest being sealing the pipe with the right amount of working fluid. As I've found out the pipe part of the heatpipe can be made with almost anything, while making one out of copper certainly helps I've made one out of sheet metal that was used as a shield on the underside of an old CRT TV main board. The sheet metal did not have great thermal conductivity but it took solder surprisingly well, and yes, as you may have very well noticed my heatpipe was not even a pipe to begin with but rolling the sheet metal up and soldering up the seam turned it into one ok looking tube. The reason the material your tube is made of is not critically important is that the heat is transferred by the working fluid. As the fluid heats up it evaporates taking some heat with it and then rushes to the cold side of the tube where it condenses and dumps the heat it's carrying. I've so far tried making several heatpipes with different working fluids, mainly stuff I had around. Since I was only messing around at first I grabbed the first suitable liquid I had on hand, which was hand sanitizing fluid (oh the puns). It was a square bottle with some blue liquid in it, presumably water and alcohol mix with some colorant and bittering agent to keep people from drinking it, great for cleaning thermal paste I might add. As a working fluid it was also not bad. I might have put a little too much of it in the pipe because it takes some time to start working but when the other end gets hot it pretty much heats up instantly. In total I've made six heatpipes and of the six only three remain operational, two of them being more than a week old. The third one I made today and despite me being quite prepared this time with proper brass tube and a fresh bottle of acetone to use as a working fluid it took quite a while to get the tube working. The issue was that I was trying too hard not to add too much working fluid into the tube to keep it from being flooded. In the end the working fluid evaporated off as I heated the tube before sealing it off and I'd end up with too little working fluid to transfer any heat. Sealing the tube was also quite a challenge as well. At first I would just flatten the end of the tube and solder it up. Biggest problem with doing that is that you need to hit the sweetspot where the pressure inside the tube is almost the same as ambient pressure because the flattened end would always leak some pressure and if you didn't solder the end quite right it could end up either sucking the solder in or spitting it out. My solution to the sealing off problem was to solder a capillary tube from a refrigerator into the end of the tube and squish it when the tube is just about ready, the end of the tiny tube would be soldered shut for an improved seal.
Looking at all the text I've written so far it would be rude of me to not include a picture of at least one of the heatpipes I've made, so here you go.
This one here is the one I did today. In the end I got tired of the acetone evaporating from it so I basically overfilled it just to see how much it takes to get it to work and it did work but I might have put a bit too much acetone in it because I can feel it bubble when I heat the bottom.
I lined the inside with some woven shielding from some very old tech but it was pretty easy to put in and it did suck the acetone up very well.
Pushing it together or pulling it apart made it change it's size making it easy to fit in most tubes.
Here it is in the brass tube.
In reality it's taking up a little less space than in looks like from the picture because after I trimmed the end I had to push the shielding back in and the end got a little messy. The shielding is supposed to help the tube efficiency be less dependent on the tube orientation.
In the near future I plan on using liquid butane as my working fluid and electroplated porous copper as my wick. I think it's going to produce better, more repeatable results.
That's it for now, thanks for reading.
A couple of weeks ago i got quite interested in heatpipes, I can thank my overheating laptop for that.
Heatpipes as a whole are very interesting little things and getting one to work properly is not that easy. When making a heatpipe obtaining the materials is probably the easiest part, the hardest being sealing the pipe with the right amount of working fluid. As I've found out the pipe part of the heatpipe can be made with almost anything, while making one out of copper certainly helps I've made one out of sheet metal that was used as a shield on the underside of an old CRT TV main board. The sheet metal did not have great thermal conductivity but it took solder surprisingly well, and yes, as you may have very well noticed my heatpipe was not even a pipe to begin with but rolling the sheet metal up and soldering up the seam turned it into one ok looking tube. The reason the material your tube is made of is not critically important is that the heat is transferred by the working fluid. As the fluid heats up it evaporates taking some heat with it and then rushes to the cold side of the tube where it condenses and dumps the heat it's carrying. I've so far tried making several heatpipes with different working fluids, mainly stuff I had around. Since I was only messing around at first I grabbed the first suitable liquid I had on hand, which was hand sanitizing fluid (oh the puns). It was a square bottle with some blue liquid in it, presumably water and alcohol mix with some colorant and bittering agent to keep people from drinking it, great for cleaning thermal paste I might add. As a working fluid it was also not bad. I might have put a little too much of it in the pipe because it takes some time to start working but when the other end gets hot it pretty much heats up instantly. In total I've made six heatpipes and of the six only three remain operational, two of them being more than a week old. The third one I made today and despite me being quite prepared this time with proper brass tube and a fresh bottle of acetone to use as a working fluid it took quite a while to get the tube working. The issue was that I was trying too hard not to add too much working fluid into the tube to keep it from being flooded. In the end the working fluid evaporated off as I heated the tube before sealing it off and I'd end up with too little working fluid to transfer any heat. Sealing the tube was also quite a challenge as well. At first I would just flatten the end of the tube and solder it up. Biggest problem with doing that is that you need to hit the sweetspot where the pressure inside the tube is almost the same as ambient pressure because the flattened end would always leak some pressure and if you didn't solder the end quite right it could end up either sucking the solder in or spitting it out. My solution to the sealing off problem was to solder a capillary tube from a refrigerator into the end of the tube and squish it when the tube is just about ready, the end of the tiny tube would be soldered shut for an improved seal.
Looking at all the text I've written so far it would be rude of me to not include a picture of at least one of the heatpipes I've made, so here you go.
I lined the inside with some woven shielding from some very old tech but it was pretty easy to put in and it did suck the acetone up very well.
Here it is in the brass tube.
In the near future I plan on using liquid butane as my working fluid and electroplated porous copper as my wick. I think it's going to produce better, more repeatable results.
That's it for now, thanks for reading.
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