Apple looking into liquid-cooled MacBooks
Apple is looking into the use of liquid coolants to transport heat in its notebook computer designs, a controversial technique it employed briefly on its line of dual processor Power Mac G5s several years ago.
In a 12-page patent request originally filed in May of last year and published for the first time last week, the Mac maker notes that significant increases in the computational performance of electronic devices over the past few years has made it harder to maintain acceptable internal and external operational temperatures in those devices.
"Portable devices, such as laptop computers, cellular telephones, and personal digital assistants have additional design constraints which make it even harder to manage thermal load," the company said.
In particular, Apple noted that size and weight limitations in such devices can make it difficult to achieve desired operational temperatures. For example, in many portable devices the size and weight of metal heat sinks may be prohibitive, while battery life constraints in such devices may limit the available power for active cooling mechanisms, such as fans.
As a potential solution, Apple proposes a system that includes a power source that is coupled to a heat pipe, where the power source includes an integrated circuit.
"This heat pipe may contain a liquid coolant that has a density greater than a first pre-determined value at room temperature," the filing explains. "A pump is coupled to the heat pipe is configured to circulate the liquid coolant through the heat pipe. Furthermore, a heat exchanger coupled to the heat pipe is configured to transfer heat from the heat pipe to an environment external to the computer system."
More specifically, Apple said the the heat pipe could have a solid copper jacket with a hollow interior that includes a liquid coolant such as water, a coolant in an R133 group of coolants, or a coolant in an R134 group of coolants. The coupled pump would then circulate the liquid coolant, facilitating heat transfer from a power source in the computer system to forced-fluid drivers --such as fans -- that would be located at opposite ends of the heat pipe.
The forced-fluid drivers could also circulate a fluid via fluid-flow ports -- such as vents -- that are tapered such that a cross-sectional area decreases as fluid flows from inside of the computer system to outside the computer system.
"For example, the fluid-flow ports may constitute a Venturi tube," the filing explains in more detail. "Note that this decrease in area may give rise to a Bernoulli effect in which a partial vacuum at the output of the fluid-flow ports (and at the input to fluid-flow port) reduces and/or eliminates recirculation of the fluid flows, thereby reducing the temperature inside of the computer system."
Other variations of the invention could include a mechanical pump or an electrostatic pump. Alternatively, the pump could be configured to circulate the liquid coolant using mechanical vibration such as ultrasonic frequencies of a membrane.
A move towards liquid cooling on its notebook lines wouldn't be Apple's first foray into the liquid cooling Mac business. In the spring of 2004, the company introduced the liquid-cooled dual 2.5GHz PowerMac G5.
The cooling systems were developed for Apple by Troy, Mich-based Delphi, also known as Delphi-Harrison -- a former division of General Motors. As such, they resembled miniature automobile radiators and included a pump, radiator, grills, and a power cable [visual diagrams].
Use of the liquid cooling systems were short lived, however, as they were prone to leaks. As the systems aged, coolant would spill out of the pipes, damaging users' property while also frying many of the PowerMac's internal components along the way. In several cases, Apple determined that it was uneconomical for them to repair the systems and instead began replacing them outright on its own dime.
In a 12-page patent request originally filed in May of last year and published for the first time last week, the Mac maker notes that significant increases in the computational performance of electronic devices over the past few years has made it harder to maintain acceptable internal and external operational temperatures in those devices.
"Portable devices, such as laptop computers, cellular telephones, and personal digital assistants have additional design constraints which make it even harder to manage thermal load," the company said.
In particular, Apple noted that size and weight limitations in such devices can make it difficult to achieve desired operational temperatures. For example, in many portable devices the size and weight of metal heat sinks may be prohibitive, while battery life constraints in such devices may limit the available power for active cooling mechanisms, such as fans.
As a potential solution, Apple proposes a system that includes a power source that is coupled to a heat pipe, where the power source includes an integrated circuit.
"This heat pipe may contain a liquid coolant that has a density greater than a first pre-determined value at room temperature," the filing explains. "A pump is coupled to the heat pipe is configured to circulate the liquid coolant through the heat pipe. Furthermore, a heat exchanger coupled to the heat pipe is configured to transfer heat from the heat pipe to an environment external to the computer system."
More specifically, Apple said the the heat pipe could have a solid copper jacket with a hollow interior that includes a liquid coolant such as water, a coolant in an R133 group of coolants, or a coolant in an R134 group of coolants. The coupled pump would then circulate the liquid coolant, facilitating heat transfer from a power source in the computer system to forced-fluid drivers --such as fans -- that would be located at opposite ends of the heat pipe.
The forced-fluid drivers could also circulate a fluid via fluid-flow ports -- such as vents -- that are tapered such that a cross-sectional area decreases as fluid flows from inside of the computer system to outside the computer system.
"For example, the fluid-flow ports may constitute a Venturi tube," the filing explains in more detail. "Note that this decrease in area may give rise to a Bernoulli effect in which a partial vacuum at the output of the fluid-flow ports (and at the input to fluid-flow port) reduces and/or eliminates recirculation of the fluid flows, thereby reducing the temperature inside of the computer system."
Other variations of the invention could include a mechanical pump or an electrostatic pump. Alternatively, the pump could be configured to circulate the liquid coolant using mechanical vibration such as ultrasonic frequencies of a membrane.
A move towards liquid cooling on its notebook lines wouldn't be Apple's first foray into the liquid cooling Mac business. In the spring of 2004, the company introduced the liquid-cooled dual 2.5GHz PowerMac G5.
The cooling systems were developed for Apple by Troy, Mich-based Delphi, also known as Delphi-Harrison -- a former division of General Motors. As such, they resembled miniature automobile radiators and included a pump, radiator, grills, and a power cable [visual diagrams].
Use of the liquid cooling systems were short lived, however, as they were prone to leaks. As the systems aged, coolant would spill out of the pipes, damaging users' property while also frying many of the PowerMac's internal components along the way. In several cases, Apple determined that it was uneconomical for them to repair the systems and instead began replacing them outright on its own dime.
Comments
http://jason.de-villa.net/blog/?p=230
I'm pretty sure the first heatpipes I saw in a mac was my 800MHz lampy iMac.
Sheldon
As such, I can't say I'm excited to read this news. Laptops get bumped and shaken around a lot more due to their mobility. Any liquid solution they come up with had better be MUCH more reliable.
Did they not learn anything from the coolant leaks on the G5. Besides, liquid cooling adds uneed bulk and weight
Uh.. yes... perhaps they are taking what they learned from the G5 and refining it? Success is usually created after learning to fail. Works in a lot of areas.
Copper filled with fluid? Sounds heavy, unless they get rid of the heat sinks all together.
As such, I can't say I'm excited to read this news. Laptops get bumped and shaken around a lot more due to their mobility. Any liquid solution they come up with had better be MUCH more reliable.
I think most notebooks use heat pipes, I haven't heard of those failing systematically like the G5 liquid cooling rigs. I don't think that's what is being patented here. One of the claims looks like something similar to a magneto-hydrodynamic pump device, somewhat like the "caterpillar" drive made popularly known in The Hunt For Red October. Basically, apply a magnetic field through a fluid and it pushes fluid to flow, here, in a loop, without the bother of pistons, fans or other solid objects moving. It still uses fins to dissipate heat, most heat pipes have fins attached on the condenser end, though heat pipes are generally not formed into a loop, this is a loop. Still, MHD is not a very efficient way to get fluid to flow. It might be the reason for metalic particles in the fluid in a figure in the patent filing. I'm a little exhausted to really give the story a thoughrough reading.
But they need to do something. The fan situation is a little out of control on my white macbook. My Santa Rosa MBP does better.
They allready do use a liquid for cooling. They use heat-pipes as seen in this x-ray:
http://jason.de-villa.net/blog/?p=230
I'm pretty sure the first heatpipes I saw in a mac was my 800MHz lampy iMac.
Sheldon
These heatpipes do not contain a liquid. They are purely for transferring heat to metal heatsinks through the copper by conduction.
I was one of the unfortunate owners of a liquid-cooled Dualie G5. It died suddenly and without notice in around (perhaps less) two years of use. The only time I didn't have applecare, too.
As such, I can't say I'm excited to read this news. Laptops get bumped and shaken around a lot more due to their mobility. Any liquid solution they come up with had better be MUCH more reliable.
As the article stated, and also noted on xlr8yourmac.com, Apple replaced the leaking G5's on their own dime, regardless of warranty. They even replaced them with new Mac Pro models after the G5 was discontinued.
You would have thought people would realise by now that sometimes, it takes Apple a while to get around to filing patents. In this case, this looks like evidence that Apple worked on liquid cooling for a G5 PowerBook, but it never saw the light of day.
the patent could be a way to hedge your bets - not so specific as to give away any plans - vague enough to cover future potential products - but also as insurance in case something like liquid cooled notebooks becomes necessary. Although I suspect you are right - this might even have been one of the reasons to switch to Intel for chips - to avoid liquid cooling for a notebook.
For the record water has a much higher heat capacitance than air and so is far more effective at moving heat around - it would seem the idea is to use the fluid to get the heat from the small area (CPU chip for instance) where it is generate to another area where it can be more effectively dissipated. In a self contained system the liquid doesn't provide any additional cooling capacity - only the ability to move the heat around to where you can deal with it more effectively.
Also as an FYI - IBM has been using liquid cooling in mainframes for years - and has recently introduced a number of water cooled products - including systems with fluid in components which are in contact with CPUs - in these systems there is external plumbing and the fluid is circulated in such a way that water chillers can be used to remove the heat much much economically that can be done with air chillers that have to deal with entire rooms. Including an add on for racks that is a basically a water filled door which allows the technology to be deployed strategically where it is needed.
http://www.happynews.com/news/121200...efficiency.htm
it would seem like a great way to decrease heat and increase battery life at the same time
iCarbon (knows it isn't ready for prime time, but thought apple might want to patent it now...)
I think that Apple wants to reduce the TDP in its notebooks rather than use hotter processors and cool them with fancy, expensive liquid cooling systems.
Speed, low heat, inexpensive to make. Pick any two.
Unless the liquid circulates, a solid metal heat pipe works pretty well. Could this be a patent that came out of research reagrding putting a G5 into a notebook?
I think that Apple wants to reduce the TDP in its notebooks rather than use hotter processors and cool them with fancy, expensive liquid cooling systems.
Speed, low heat, inexpensive to make. Pick any two.
I agree that actual liquid circulating around is an engineering nightmare. It's very difficult to implement even in desktop systems.
However, heatpipes are probably the likely avenue for "liquid" cooling. Probably in the next few years we might see a bit more heat pipe applications in laptops. It's not a huge issue, it's used very commonly and is, well, essential, for fast GPUs and motherboards, CPU heatsink-fans, etc. in custom-built "overclocking" desktops.
The challenge with heatpipes in laptops would be it's about thermal "channeling". Because whatever heat that is generated and transfered, even liquid-cooled, that heat has to be removed. Still, by fans. I'll try to elaborate.
In desktop overclocking, heatpipes are used as a way to most rapidly get heat *away* from the highest-performing components like GPU and CPU cores. This heat is then "dumped" by usually fast, noisy fans towards the rear of the desktop casing. Law of thermodynamics or something, all that heat generated still has to exit the desktop or laptop unit somehow.
In laptops, I would imagine that heatpipes or a "heat-channeled membrane" that the logic board sits in is a way of most efficiently transferring all heat to the vents. Particularly, to avoid a lot of heat buildup at the bottom of the laptop, and dedicate the "heat dumping" areas of the laptop to be at appropriate rear or side vents, not close to your family jewels, for example.
IMHO, things could play out in a few ways. Lowering TDP and Intel's continuing work could really mean much greater cooling efficiency. However, if Intel hits a few snags, Apple would need to put in a bit of heatpipes here and there.
I don't know if it affects the LED display in some way, but to me, the huge back part of the screen casing seems like a nice, large-surface area, away from human contact where you could have pores/vents/etc.
A radical idea would be, imagine if heat generated in the main unit would be transferred via heatpipes/ heat-transfer-membranes to a series of "fins", pores, tiny fans embedded in the display. This combined with the traditional rear fans in the main body of the laptop... would be really cool. Heh, pun unintended.
What I don't understand is why no one is trying to rescue that heat with thermo-electric materials? they're working with them on cars for the x-prize...
That is also a f*king great idea. All that waste thermal energy could be recaptured instead of just dumped out of the desktop/laptop.
Macworld 2015 perhaps:
One more thing... Steve opens laptop. Runs applications at 100% of the 16 CPU cores. Unplugs power adaptor. Audience is intrigued.
Steve then removes the main battery. Audience is totally, absolutely blown away in a gigantic explosion of RDF when they see the laptop is still running, still temporarily powered mostly by the heat generation of the components being converted back to usable electricity*.
*Of course, this process may only last 5 to 15 minutes with the use of another, smaller, spare battery/capacitor, etc. But it is an exaggerated demonstration of what *could* be possible. That is, you could have an Apple laptop that runs cool, and also, in normal and high usage of CPU/GPU, the waste heat is converted *back* into electricity and hence, you still need a main battery or power adaptor, but the power draw is much reduced.