Looking somewhat like the load for a microwave waveguide, the incredibly tall, 145mm high TS Heatronics NCU-1000 heatsink is a remarkably simple device. A 5mm copper baseplate sits below the bottom of the Akachi heatpipe that stretches out in a "U" shape to a total length of about 315mm, and a stainless steel plate sits on the opposite side, held in place with four screws. The Akachi heatpipe, or Heatlane heatpipe as the company are marketing it, then increases its total surface area with the aide of dozens of folded aluminum cooling fins.

Traditional heatpipes are really neat devices; as heat energy enters into the pipe, water under a vacuum is converted to a vapour (water boils at a lower temperature when there is less atmospheric pressure). That vapour transfers the heat it has absorbed as it travels towards the cooler end of the heatpipe.

As the steam reaches the colder side of the system it begins to condense, and as it returns back to a liquid it dumps all that thermal energy into the surrounding metal which impart transfers it to cooling fins. A physical property know as capillary action then takes hold and draws the freshly condensed liquid back along a wick structure to the hot end of the heatpipe where the entire process repeats.

What goes on inside the Akachi heatpipe is similar to this process, but the technology has a few distinct differences. First of all, where a standard copper heatpipe uses water as a working fluid, this Akachi pipe uses a slightly more exotic hydroflurocarbon-134a (HFC-134A).

The working fluid once heated, circulates through a "meandering capillary tube" that is formed from about 30 individual 1mm x 1mm channels within the 2mm thick x 60mm wide extruded aluminum pipe structure. If you're a little unsure of what that describes, just look at the edge of a corrugated cardboard box where you see all those little folds, and visualize pretty much the same thing in aluminum.

If the side of the NCU-1000's Heatlane pipe reminds you a little bit of corrugated cardboard you're not that far off. While it seems as though it's a solid bar of metal, the strip of metal is actually composed of 30-40 very tiny pipes joined side-to-side. You can see the outlines of these pipes in the picture above.

Invented by Hisateru Akachi who called the technology "self-excited oscillation heatpipe", the Akachi pipe works something like this...

(Note: The English documentation is a bit vague, so I may be off on some of the fine points.)

The working fluid is loaded into the tiny 1mm x 1mm sized capillaries of the pipe under pressure, and with small pockets of a gas every so often. As an area of the flat Heatlane pipe is heated, the working fluid in those pipes directly behind the heatsource (in our case the entire width of the pipe, or 30-40 individual pipes) expands slightly as it transforms to heat-carrying vapour.

That expansion of the working fluid into a vapour, into the small microvoids, drives all of the fluid and vapour in the entire system to move forward/backward (oscillate) at a certain velocity.

All the little pipes in the entire Heatlane heatpipe are connected, so whatever happens at one point drives everything else - kind of like slurping soda through a curly straw with a bunch of trapped air bubbles... The oscillating motion transfers the heated vapour to a cooler area of the Heatlane pipe where the latent heat is then transferred to the surrounding cool metal structure. The cooled vapour then condenses back to a working fluid, and the process continues on ad infinitum as long as the heating and cooling conditions are maintained.

TS Heatronics have a quick video of the process in motion on this page, taken with an X-ray machine so you can actually see the little vapour bubbles and working fluid racing through the aluminum Heatlane pipes. It all looks curiously like a busy 16 lane highway. :)