Ah, cooling. It’s funny how such a simple little thing — making something cooler — can play such an important role in modern civilization. From refrigerators to car radiators, from air conditioning to keeping your computer’s CPU from melting, cooling technology is big business. Just the tiniest of efficiency improvements can result in savings of millions of dollars of electricity, significantly faster computers, or more reliable machines. Now, researchers at Stanford say they’ve created a passive (i.e. free) radiator system that cools by beaming heat directly into outer space; not the local urban environment or the atmosphere, where the heat eventually comes back to haunt us, but deep, ultra-cold space.
Whether it’s an air conditioning unit or the heatsink and fan in your computer, cooling is concerned with just one thing: Moving heat from one place to another place. In accordance with Newton’s first law of thermodynamics — the law of conservation of energy — that’s all you can really do. In the case of air conditioning, you are taking heat energy from inside your home and dumping it outside — which is great if you’re indoors, but not so great if you’re outside. Your refrigerator and PC do the same thing, but on a more localized scale: Have a feel behind your fridge or freezer sometime and check out how warm it is back there. In addition, don’t forget that these systems are consuming electricity — and thus producing yet more heat — to move that unwanted heat around.
Another innovative cooling solution: The fanless, spinning heatsink
It’s all a bit crappy, if I’m honest, but currently it’s the best solution that we have.
Now, however, some researchers at Stanford University have a rather ingenious new take on cooling. For a start, their new device (pictured top) is passive: If you warm it up, it will naturally radiate that thermal energy. This in itself is nothing special — but it doesn’t let you cool beyond the ambient temperature, which makes it rather useless for air conditioning, refrigeration, and most other applications of cooling. To get around this problem, Stanford’s device radiates heat directly into outer space — and because the temperature of outer space is close to absolute zero (-270 Celsius, -454 Fahrenheit), it never runs into the ambient temperature problem. In theory, this new passive radiator could keep dumping excess heat into outer space until the whole universe is the same temperature as the surface of Earth — but I doubt humanity will be around long enough for that to happen. [Research paper: doi:10.1038/nature13883]
Read: The end of Earth, the end of us, and the end of the universe
An illustration of Stanford’s photonic radiative cooler. Yellow is the reflected sunlight, red is the radiated-into-space thermal energy, resulting in a cooler (blue) building.
How does the Stanford device — officially known as a photonic radiative cooler — radiate energy into deep space, then? Well, the radiator consists of seven alternating layers of silicon dioxide and hafnium oxide, on a reflective base layer of silver, that are specially tuned to absorb energy and then radiate at a very specific frequency of far-infrared (between 8μm and 13μm). According to the researchers, the Earth’s atmosphere is “transparent” to wavelengths between 8 and 13 micrometers — and so the radiation just keeps going, unperturbed by clouds or carbon dioxide or anything else that might keep the heat inside the atmosphere.
Some problems remain, however. First, because this is a passive device, it’s still fairly limited in the cooling that it can provide — up to five degrees Celsius (9F) below ambient air temperature, in this case. Second, the photonic radiative cooler must have a clear view of space — so it needs to be on your roof. This means that, a) you still have to get excess heat from your house/office/school to the roof (not too bad) — and b) the radiator is highly reflective, which could be disruptive to planes and birds. On the plus side, it’s worth mentioning that it should be very cheap and easy to make these photonic radiative coolers — any old photovoltaic solar panel factory could churn these out instead, I think.
On its own, Stanford’s photonic radiative cooler probably isn’t going to cool your office or home — especially if you live somewhere very hot — but it could certainly provide some cooling, and it’s more efficient than using rooftop solar panels to power an air conditioning system. Plus, irrespective of whether Stanford’s device is ever commercialized, the bigger takeaway is that their discovery changes our worldview — if our inventors can find ways of pumping heat, gases, and other unwanted stuff into space, life here on Earth would be a lot more sustainable. At the very least, it would cut billions of dollars from our annual heating and cooling bills.
Now read: A fully transparent solar cell that could make every window and screen a power source
Source Article from http://www.extremetech.com/extreme/195105-stanford-uses-the-ultimate-heat-exchanger-outer-space-for-free-unlimited-cooling http://www.extremetech.com/wp-content/uploads/2014/12/stanford-photonic-radiator-image-inventors-640x475.jpg
Stanford uses the ultimate heat exchanger – outer space – for free, unlimited cooling
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