fter hearing about Cool Chips™ thermotunnel technology, many people find that they have questions regarding what Cool Chips are, how they work, and how they might be applied in specific cooling solutions. This page is intended to address those issues.
If you have a question that is not answered here or elsewhere on our site, please feel free to contact us, or send an e-mail to email@example.com.
Q - How do Cool Chips work?
A - By applying an electric current, heat, in the form of energetic electrons, is made to "tunnel" from one side of a tiny vacuum gap to another. This process is called thermotunneling and is based on known principles of quantum physics. For more information on the theory, see:
Hishinuma Y, Geballe TH, Moyzhes BY, Kenny TW (2001) Refrigeration by combined tunneling and thermionic emission in vacuum: use of nanometer scale design. Applied Physics Letters 78 (17):2572-2574.
Q - Have actual devices been built?
A - Yes. Physical devices have been in the lab since 1998. Pictures are available on our website.
Q - How do you claim such high theoretical outputs?
A - The Stanford paper (see above) projects outputs for known materials as high as 5000 watts/cm². Because of other limitations, we expect the maximum practical output to be on the order of hundreds of watts/cm². However, long before development begins approaching anywhere near these maximum outputs, Cool Chips™ with a density projected at 3-5 watts/cm² will be more than adequate for meeting most cooling requirements.
Q - Heat can't disappear, so where does it go?
A - To the other side of the chip. From there it still has to be dissipated like normal except that the cool side stays cold and can be used to cool, for example, computer chips or the inside of a refrigerator.
Q - Why is this better than standard systems like compressor cooling systems?
A - There are many advantages. Cool Chips will use less electricity for the same amount of cooling. They are solid state, so there are no moving parts to wear out. They can provide precise temperature control, they are silent, and they use no environmentally-suspect gas or fluid refrigerants.
Q - How much power do they use?
A - Cool Chips use very low voltage and high current, but the total power consumption depends on the heat load and the delta-T between the two sides. See: http://www.coolchips.gi/technology/ccalc.shtml
Q - How do I get hold of one for testing?
A - Current hardware prototypes have proved the concept of Cool Chips and research, both our own and independent research, shows the theoretical performance levels. We expect to have commercial prototypes available in 6-8 months from getting funding for the final stage of development.
Before that time, prototypes are only available to potential industrial partners who are prepared to help underwrite the costs of that development stage.
Q - Why haven't we heard of this before?
A - There has been a certain amount of publicity in trade and specialist journals, but we have not been seeking general publicity until we were in a position to talk freely about the thermotunneling process we are using. Now that patents are issued and others are pending, we are seeking licensees and development partners to bring the technology to market.
Q - How much will it cost?
A - We anticipate a marginal cost per watt of cooling capacity on the order of pennies. The materials used are inexpensive, and the purities required are low. For manufacturers, the unit price will be highly competitive with existing systems. The price manufacturers charge consumers depends on other factors such as the typical overheads in that market, how competitive it is, how much regulation and testing are required for an application, and so on.
More Technical Questions
Q - How efficient are Cool Chips?
A - Cool Chips are projected to have efficiencies of 55% of Carnot efficiency.
Q - How efficient are they at the moment?
A - We are not testing for cooling at the present, so no efficiency measurements have been made. We know what we want to do to increase the uniformity of the effect, which is an engineering issue, and we are seeking the funding and collaboration to do that.
Q - What is 'Carnot efficiency?'
A - The Carnot equation describes the efficiency at which a perfect heat pump would operate if there were no other energy losses - an impossible level of perfection. This number will change depending on the temperatures of the hot and cold sides. For example, a perfect heat pump will be use energy more efficiently when the difference between hot and cold is only 10 degrees, than when the difference is 50 degrees. This can also be called the Maximum Possible COP (Coefficient of Performance).
But no matter how much the Carnot efficiency changes, the projected efficiency of Cool Chips will be 55% of that figure. This compares very favorably with compressor systems, which are typically 45% of Carnot efficiency, and Peltier thermoelectric systems, which are typically 8-10% of Carnot efficiency.
Q - Isn't quantum tunneling extremely inefficient, because it is just a matter of chance? Some electrons may tunnel across the gap, but many others won't.
A - It is true that quantum tunneling is based on the probability of electrons being in one place or another at a given moment. However, the electrons that tunnel will always be the ones with a high kinetic energy, since they are at the peak of the probability wave function, enabling them to appear on the other side of the gap. This means that they are the 'hottest' electrons, borrowing energy from the cold side, and dumping it on the hot side before being drawn into the electric current flowing back to the cool side.
If you were just looking at a few such events, then the probabilities would make for a very unpredictable device. But with many millions of events over a relatively wide surface area, the end result becomes highly reliable.
Q - Won't electrostatic attraction force the plates together with pressures of tons per square inch? What about electronic creep?
A - There are electrostatic attraction as well as atmospheric pressures. The piezo elements used for positioning are more than strong enough to handle these pressures.
Electrostatic force is approximately 1 kg/cm² for a 10 nanometer gap between electrodes and 1 V of applied voltage. Forces on that order do not create considerable technical problems.
Electronic creep is more of a problem as materials get hot: Cool Chips operate at very low temperatures compared to the melting points of the metals used.
Q - There is no such thing as a near-perfect (or even really good) temperature insulating solid material -- the only pretty good temperature insulation is... a vacuum. Any decent vacuum over a nano-scale gap is going to close, right?
A - The gap is readily maintained in vacuum; we already do this. Actually, there is a temperature insulator that is as good as vacuum for our purposes: a gas with very close spacing between the electrodes. If the space available is less than the mean free path of the gas electron, then virtually no heat transfers across the gap. This technique is used, to some effect, in today's refrigerator insulation and aerogels. Cool Chips' insulation is still better than that used in insulation, because the return path for the heat is all the way around the device, not down the side wall of a gel.
Q - Doesn't the device have to pull away unbound electrons marginally faster than they are injected to provide cooling?
A - Cooling is not provided by pulling away electrons more quickly than they are replaced. Cooling is provided by pulling away hot electrons, and replacing them with cool ones from the circuit. This work is provided by expending electricity. The substrate is not stripped.
Q - Aren't photons generated on the hot side, which reduces efficiency?
A - Not significant amounts at this low temperature. Photons are radiative, and radiation losses at normal cooling temperatures are a loss term of <1%.
Q - Wouldn't you get arcing which would create unwanted heat?
A - If the surfaces are very uneven, arcing may occur at sharp edges. In operation, these edges are destroyed through ablation, so the arcing is eliminated. Note that at low voltages, arcing is not a common problem.
Q - As one side gets hotter, doesn't that brake the tunneling?
A - No. The most active electrons tunnel, so you will get more tunneling current with hotter active areas than with colder. As the temperature difference between the two plates increases, the amount of work needed to "push" the electrons uphill is increased, so the thermodynamic efficiency falls, as is predicted by Carnot. See our cool calculator for examples.
Q - What happens if the inside of the fridge gets ionized from the electron flow?
A - The Cool Chip is sealed providing thermal, but not electrical, connections to the inside of the refrigerator. We don't anticipate ionization being a problem.
Q - Isn't this a variant of Maxwell's Demon, a well-known example of violating the Second Law of Thermodynamics?
A - Maxwell's sorting demon was imagined to be a "nimble fingered being" which would sort particles without the external input of energy, and without causing an entropy increase elsewhere in the universe. For example, all of the hot molecules of gas would be sorted to one side of the chamber, and all of the cold molecules would be sorted to the other side, reducing the entropy of the gas in the container.
There is nothing wrong with reducing the entropy of a container of gas, but you must do work, and the entropy of the entire universe must increase (or at best remain constant) in order to obey the Second Law of Thermodynamics.
Our Cool Chips carry out a form of "sorting", removing the higher energy electrons from an electrode whilst leaving the lower energy electrons behind, thus cooling the electrode. However this sorting requires that electrons flow in an electric field, meaning that work must be done. This work is supplied in the form of electrical power being fed to the device.
Hence we are not providing something for nothing. "Maxwell's demon" is supposedly powered by its own environment, but with Cool Chips, you need an external power source.
Q - What were the tests Boeing did? Was it an evaluation or a proper test? Did they test hardware or just a theory?
A - We can't comment on the details of Boeing's evaluation. However, we can draw attention to their press release where they state that "The evaluation, conducted under an agreement with Cool Chips plc...showed that the principles under which the new Cool Chips technology operate are sound, that the measured physical data complied with the theory, and that further development and evaluation are needed."
We can state that the "measured physical data" refers to data measured by Boeing from prototypes tested in a Boeing facility by Boeing staff, and that the "theory" referred to is the theory of thermotunneling we are now describing publicly.
And yes, they tested hardware.
Q - If Cool Chips work, then why haven't you measured actual cooling?
A - In order for cooling to occur, high tunneling current needs to be achieved. So maximizing the tunneling current has been our focus and we have been optimizing our prototypes to get as much current as we can. If the current is high, then the cooling is not at issue scientifically -- scientists in that field all confirm this.
However, the equipment needed to build chips capable of being accurately tested for cooling is expensive, and a royal pain to set up and calibrate. Remember that we need to be able to exclude all other possible sources of heat exchange in order to accurately test the cooling effect. We have produced cooling but not as part of a controlled experiment that we can report as scientifically verified cooling.
When we have developed the tunneling currents to a suitably high level, the cooling will be of a commercially useful quantity and we figure that's the best time to do the expensive tests instead of spending a lot of time now to show a small amount of cooling. We believe we can demonstrate cooling now and if anybody wants to test our chips and is willing to pay for the tests, we would be interested.
None of this has anything to do with efficiency, in the sense of how much work you get out of a Cool Chip for the energy you put in. The tunneling current already operates at a very high level of efficiency in line with our predictions -- in fact the laws of physics say it must do so, and our work with Boeing in 2001 confirmed this. Our current goal is to increase the robustness and engineering quality of the prototypes so that more energy can be converted (or pumped) by them and higher currents obtained -- at the same high level of efficiency.
It is like having a car that goes 100 miles to the gallon, but the prototype won't run faster than 20 mph because it's been bolted together very roughly and falls apart at higher speeds. You know from the math that you can run it at 80 mph and still get 100 miles to the gallon out of your ultra-efficient engine, but you need to spend money on a better, aerodynamic frame and chassis before you can demonstrate that.
Our lab manufacturing techniques, while way ahead of anything that's been done before, are still a little rough by the standards required to get currents high enough for commercial cooling. That's not because we don't know how. It's because we don't have the money for the facilities we need to do it. Raising those funds -- $10-15 million, not a massive sum by any means -- is what we need to do next, for what should be the last leg of the development process.
Questions about Applications
Q - What's the point in moving heat just a tiny distance? Surely it will just heat up the place it left over again.
A - Cool Chips still need a heat sink or fan or similar device for dispersing the heat once it has been removed from its target. In the case of a domestic refrigerator, for example, you have a unit which takes the heat out of the air inside the fridge and vents this heat out of the back with a fan. If you turned the power off, of course the heat inside and outside the fridge would slowly equalise. But as long as you keep the power on, the fridge is continually cooled and the rest of the room warmed just a little bit by the hot air from the back.
Cool Chips will have the same effect. For example, inside a computer the CPU is sensitive to over-heating. As long as you are keeping the material of the CPU (and any other sensitive components) cold, you don't much care how hot the air in the case gets as a result.
Q - You can't possibly cool a room with a plate two inches square. It would get white hot!
A - We aren't suggesting that the whole air-conditioning system would be two inches square. When we say that two inches square "will have the capacity to provide the air-conditioning for a living room", we are talking about the cooling load. We're not suggesting that Cool Chips alone would be the only components in a complete system - you would still need fins and/or a fluid loop to help collect heat from the air and heat sinks or heat pipes or fluid loops to funnel the heat from the back of the chip to the other side of the wall for dispersal. All of these are necessary to existing systems and would remain necessary. However, you would not need a compressor, which means your unit would be smaller overall, be silent, and require less maintenance because there are no moving parts.
Q - How would Cool Chips be used in a computer?
A - By actively cooling the central processor unit (CPU) you can use faster chips than are currently in use. Also, chips that are very cold run faster than the same chip at a higher temperature -- 'overclocking' a CPU (i.e. running it at a clock speed faster than it is rated to support) can result in instability unless active cooling is used to prevent overheating. Leakage currents in processors are also reduced if the processor runs at a lower temperature.
Semiconductor manufacturers have told us that the next generation CPUs require cooling of 100W per square centimeter. Imagine all the heat of a 100W lightbulb concentrated in an area the size of a fingernail. Cool Chips is the only technology that we expect to provide such intense cooling at any reasonable price.
Q - Peltier coolers have been occasionally held responsible for causing electrical shorts due to condensation. It would be expected the problem would be greater with a more efficient device. Maybe putting a small one inside a case to cool the circulating air?
A - The devices are sealed, and operate within a vacuum or backfill: there is no path for condensation to appear within the device itself.
The cold side of the device is sure to condense water in humid conditions, the same way a cold glass condenses water from the air. Condensation within an air conditioning unit is a design *feature*.
Where condensation can be a problem is within a computer. With appropriate packaging, this is not a problem. One particularly easy work-around is to have the cold side of the chip remain above the dewpoint. Another solution is to ensure that the chilled components are not exposed to air -- the centre of a chip, for example.
Questions about the Company and its Strategy
Q - Why are you based in Gibraltar?
A - Gibraltar is a British Territory in the European Union belonging to the United Kingdom, and it is a useful base for us as much of our work is being done in Europe. However, to be registered for trading on the OTC stock market in the USA, we must follow the SEC's regulations for foreign companies, and our directors, many of whom are US citizens, are answerable to shareholders and to the law for their actions. Gibraltar market regulations are based on UK practise and its courts follow UK law.
Q - Why aren't you listed on the NASDAQ?
A - We don't meet the technical qualifications for the NASDAQ exchange which require, among other things, that companies are large enough and have a minimum number of market makers. Also, under certain circumstances, foreign companies on the NASDAQ can be considered US companies, for tax and IP purposes. For these reasons many foreign companies prefer to trade OTC, including many well-known European companies. We review this policy from time to time, and we may well seek listings on other exchanges with the higher profile we would get from a licensing deal.
Q - What does the logo mean?
A - The logo shows a beluga whale carrying a pickaxe. The beluga whale is an Inuit symbol of good luck and prosperity (as well as an environmental symbol) and the pickaxe represents hard work and human ingenuity. The logo embodies Cool Chips' efforts to benefit from the combination: simultaneously creating wealth and helping the environment.
Copyright © 1995 - 2018 Cool Chips plc. All rights reserved.
Forward Looking Statement may be found at http://www.coolchips.gi/fwdlook.shtml.