DIY Heat Pipe

Start by distinguishing between a heat pipe and a light pipe.

Google "heat pipe". You can probably find some construction details. I even got a free sample once, the outer envelope of which is a 1/8-inch copper tube 6 inches long.

Pretty cool (or hot) as the case may be. You would be surprised at how rapidly heat traverses the length of these things.

I don't want to rain on your heat pipe, but you should look in to the materials of construction, working fluid and efficiency of this technology.Maybe you already have.

Good luck.

you might be able to get rid of the air by burning something inside the tube at one end,

match ends. sodium chlorate and sulphur or of course a vacume pump

for wick fine tubing that will cause capillary action to work mite be faster than wick material

Really confused by your post but if it is indeed a heat pipe that you are after, a McGill professor (Prof. Mucciardi) has shown me his own "demo":

Plumbing 1/2" copper tube (believe it was the cheap thin wall version), 3 feet in lenght; capped at one end and fitted with an also cheap toilet faucet at the other. Not sure about the quantity of tap water but lets say 6 to 8 onces (small drinking glass).

Pour the water in, get to boil with a propane torch applied to the cap end and once you get the heavy boiling under way, just close the valve : Vacuum has held for more than 7 years.

Incredibly fast heat transfer from a coffee cup. Also, under vacuum, if you move the pipe the right way, the water hitting the bottom of the pipe sounds like a metal ball.

Pretty sure you will have more fun with this than with any other form of collapsible tubing !!!!

You may also season the water to your taste but really not sure that such seasonning will really affect the purpose of your experiment very much...

Again, have fun !

> Start by distinguishing between a heat pipe and a light pipe.

Light pipe: optical waveguide utilising total internal reflection.
Heat pipe: transports heat through the boiling of a fluid at one end and condensing it at the other.

> You would be surprised at how rapidly heat traverses the length of these things.

Can be faster than the speed of sound. Apparently.

> the materials of construction, working fluid and efficiency of this technology

Something solid and hollow, water for the temperature range I'm after, and pretty high.
Although I'm starting to consider ethanol as the fluid. It might have too low a workable temperature (I'm wanting to put about 300 Watts through this thing), but it doesn't dissolve salt or sugar, if I end up using that for wicking.
Thoughts?

> for wick fine tubing that will cause capillary action

Will that work? I'll have to play.

> 3 feet in lenght; capped at one end and fitted with an also cheap toilet faucet at

> the other.

That's a good idea. Do you have any info on efficiency?

> you will have more fun with this than with any other form of collapsible tubing

I need a little bit of flex, it'll make this thing a lot easier to plug in.

With using copper as the pipe tho, would that not reduce the efficiency if you're trying to get heat from one end to the other? You wouldn't want any heat getting out through the wall before it gets to the other end, no?

With using copper as the pipe tho, would that not reduce the efficiency if you're trying to get heat from one end to the other? You wouldn't want any heat getting out through the wall before it gets to the other end, no?

yes good point.

you could try a thermal break in the middle, using compression fittings place a piece of plastic/pvc pipe in the centre leaving copper tubes at each end.

Copper at each end would improve thermal transfer

That's the plan. I think if I get some pretty heavy plastic hose it should be about as resistant to collapse as thin wall copper. I can also reinforce it with hose clamps.

The (main) issue remains the wick. Apparently candy floss -of all things- soaks up liquids real good. I was thinking of using this with presaturated water (ie water with lots of sugar in it) but as the water evaporates and drops the sugar there will be a steady migration of sugar to the hot end.
Kind of like an ionic transfer between elctrodes, but bigger.

So now I'm thinking of either finding another powdered crystal or similar that is common and doesn't dissolve in water, or use ethanol as the fluid since this doesn't dissolve sugar. (After a lot of research into other areas of this solar device, I am now a bit of an expert on what ethanol will and won't dissolve...)

But eths is only good in heat pipes carrying 0-130 ºC, which is probably lower than I'll be wanting. How do I figure out what the max temperature is? Is it the volume of fluid times it's specific heat capacity times the wattage? (not literally that formula, but those variables).

Also of issue is the heat capacity and enthalpic heat of the fluid which is a lot higher for water, which apparently is better. What kind of effectiveness am I likely to lose going to eths?

Maybe I should just find something water insoluble...

I would first try it without the wick. Or maybe just create a discontinuity in the internal geometry with a piece of wire inserted in to "guide" the fluid. Sounds much tougher than a wick with sugar or salt or any other stuff that may drop.