Heat Pipes or Solid Copper?

This just came up in another thread...I was wondering if anybody here knows for certain.

Are laptop heat transfer pipes (you've probably all seen 'em) technically, by definition, heat pipes (meaning they have an internally active medium that exhibits phase change)? Or are they simply heat conducting solid copper pipes?

I know many desktop CPU heatsinks have active heat pipes, but they are far rounder than the notebook equivalents...so I'm not sure....

 

They're just solid sticks of copper.

 

Heat pipes are heat pipes. Yeah in laptops they're kinda flat, but they still aren't solid copper.

Edit: Wait what? I don't think that's true across the board because I remember ripping apart an old dead laptop and finding that the copper heat pipes were actually hollow.

 

AHHH! More uncertainty! I need an answer!

 

I also need an answer! I gotta know the uncertainty is killing me.

 

Sorry for confusion! It may vary by manufacturer, age of the laptop in question, type of the laptop (the one I tore up was a really old and huge Alienware from several years ago).

Which laptop in particular do you mean? That may help us answer!

 

"Heat pipes do not have a set thermal conductivity like solid materials because they have a two-phase heat transfer. Instead, their effective thermal conductivity improves with length. A 12-inch and a 4-inch heat pipe, each carrying 100 W, will have about the same thermal gradient, so the 12-inch pipe will have the higher effective thermal conductivity. Unlike solid materials, a heat pipe will have its effective thermal conductivity changed with the amount of power being transferred and with the evaporator and condenser sizes. Effective thermal conductivities can range from 10 to 10,000 times (4,000 W/meter·K to 4,000,0000 W/meter·K) the effective thermal conductivity of copper, depending on the length of the heat pipe."

 

I was looking for a more general answer... "some do, some don't" would be fine, but Mastershroom seems pretty sure that they're all just copper. I guess I like to know if my NP8690 has true heat pipes or not...

Ya, I know what a heat pipe is dude...I was asking if what is in a notebook computer fits that definition, or if they are just psuedo-heat pipes

 

That's why Im sure in modern laptops are used heat pipes.

 

most laptops I have worked on since 2004 use a heat pipe and not a solid copper bar, the only exception I have found was a clevo model from 2008, and dont ask me which one it was ... that was a few hundred laptops ago

 

Hmm...well, maybe I just have weird laptops. I dismantled my Studio 15 after it irreparably died out of warranty, and the heat pipe was a solid bar of copper. And my 1201N's heatsink has such a thin heat pipe, I don't see how it could be hollow.

 

My friend that's wasn't about "what's heat pipe" but how greater thermal conductivity have heat pipe then copper. Copper rod having thats same dimensions like heat pipe is: heavier, pricier and have far les thermal conductivity.

 

Under this link: Imageshack - heatpipe.jpg - Uploaded by darnok44 You have photo of flat heat pipe from acer aspire 5050. It dimensions are about 10mmx2mm. Inside is some kind a mesh, but for sure its not full bar.

 

And again, you didn't answer the question. I know the thermal conductivity of a heat pipe is better...

EDIT:

Now thats helpful. That matrix is what you would expect in an active heat pipe...interesting.

 

Your question is simply imprecise. Why? Beacause I cannot tell You if really ALL so called transfer pipes in laptops are heat pipe. What I can tell you is that all laptops which I was dissasembling had heat pipes. And from technical point of view is far better to use heat pipes instead solid copper.

 

But you can and now finally told us that you have worked with these and they were in fact "heat pipes"? That is what is being asked. It is contrary to a previous answer by a different poster but might be correct. I have to believe they are heat pipes.

 

Yes they were heat pipes. And about :"That is what is being asked." - Read carefully original question and my finall answer. Is it really answer on the 1-st question. I don't think so.

 

I bought a Dell 7000 laptop in 1998!. It used heatpipes even back then.

Heat pipes can transfer ~1000 times the heat of a same-sized copper bar.

The heat transfer medium is literally steam. The pipes are in partial vacuum, which vastly decreases the boiling point of the alky/water/other stuff mix.

Wiki can easily inform you...

 

The 8690 uses a copper heat pipe.

 

Another reason most aren't solid copper is... Has anyone seen the prices of copper/oz? A dollar saved here or there, is another dollar for profit. Most I've seen have been exactly what they're called... heatPIPE, being hollow with a vacuum and a manufacturer specific type of gas/liquid filling.

EDIT* Thinking back, I have seen one machine with a solid metal "pipe" that wasn't copper, only copper coated. Possibly an aluminum alloy electroplated in copper or simply dipped in copper.

 

Even back 15 years ago when copper was loads cheaper you always saw heatpipes with a heat transfer gas/liquid inside. Remember that you're not just moving heat from point A to point B, you're also exchanging it from inside the machine to the outside via airflow over a radiator.

Beyond the price of copper imagine the manufacturing cost & complexity of a heatpipe. Gotta be a reason to add that complexity.

 

mine is most probably like that.. it sucks at transfering heat..

 

I doubt it's to do with cost, heatpipes probably cost more than a solid copper bar would since they're quite complex and would require a fair few manufacturing processes.

 

My notebook has a hollow heatpipe, and I damaged it

 

Here is a picture of the NP8690 cooling system, see the end of the heat pipes are melted shut? I would be willing to bet they are actual heat pipes, not solid sticks of copper.

 

The fact that they have pointed ends wouldn't nessesarily mean they were heat pipes, it could just be the point the molten metal was poured in at when it was cast if it were an solid bar. However, given that you have a sager, I would really doubt they were solid bars anyway.

 

Most, if not all laptops have heat pipes. Solid copper doesn't nearly have enough thermal conductivity to cool a modern laptop. And it's not that much more expensive to make a heat pipe either. The inside is hollow with a wick structure or a capillary system and a working fluid (could be anything from water to something fancier designed for the right temperature), so they save a bit on raw materials.