backtop


Print 68 comment(s) - last by oTAL.. on Jan 8 at 10:11 AM


Kronos cooling run at 8.5kilo-volts to cool a device 25 degrees Celsius - Image courtesy TheFutureofThings.com
Kronos Advanced Technologies claims that's the way we're headed

Lately, heatsinks and traditional fans have become so large that they are beginning to be obstructive and are sometimes too heavy. This is an issue on the graphics processor front in many ways, as there isn't enough room for large heatsinks, yet GPU thermal exceeds that of high-speed CPUs.

A company called Kronos Advanced Technologies is working on a method of removing heat from devices such as CPUs by using ionic discharge to create a fluid motion of air. This technology has been around for a few years and is used in products such as ionic air filters, which have no moving parts but still move volumes of air and create quite a strong breeze. The same concept is being applied to micro processor cooling.

Despite the advancement however, the volume of air moved over the CPU core is still small because the core surface area is small. Heatsinks are used to increase surface area of the hot surface, so that when air is moved over the fins, more heat can transfer to the air. The Kronos' device will attempt to remove hot air away from the processor core directly without the need for heatsinks. With this method, the velocity of air being moved needs to be extremely fast in order to compensate for the lack of surface area -- and speed is something that ionic air "movers" lack.

Right now, Kronos is still working on prototypes, which it claims are scalable from very small micro coolers to large scale sizes. Power requirements also appear to be quite steep at this point in time. One of Kronos' demonstration shows a heated area being reduced from roughly 50C to 25C using an ionic cooler, but the power supply required around 8.5kV, or 8500 volts, to stay stable.


Comments     Threshold


This article is over a month old, voting and posting comments is disabled

RE: 2.5kV?
By masher2 (blog) on 1/4/2007 4:30:09 PM , Rating: 5
Voltage is not power, and extremely high voltages are not inherently dangerous. I've touched conductors carrying several hundred thousand volts before without harm, because the amperage was extremely low.

Electricity can kill you a couple of different ways. Within a specific amp range, it can cause your heart to fibrillate...but higher or lower than this and you're safe. Or, regardless of the amperage, it can carry enough power to simply fry you directly. In both cases, the voltage is only critical as long as its high enough to allow conduction through your body.


RE: 2.5kV?
By Griswold on 1/4/2007 6:18:53 PM , Rating: 2
Too vague.

Let's say you touch 100kV and we assume a body resistance of 1000 Ohm (from hand to foot), we will see a current of 100mA flowing through your body (I=U/R). That is twice of what is considered the threshold to potentially dangerous currents.

It is, however, not an issue if you're properly insulated from ground potential - and that is most likely what you were when you touched that conductor (I assume it was one of those demonstration thingies that make your hair stand up and the like).

There is a reason why 50V (AC @50Hz) is considered the safety threshold for humans. For DC, it is 120V.

Also, ventricular fibrillation is not only a result of current flowing through your heart. Frequency is also a important factor.


RE: 2.5kV?
By Griswold on 1/4/2007 6:29:28 PM , Rating: 1
Oops, there is a typo. Can you find it (order of magnitude)?


RE: 2.5kV?
By ChronoReverse on 1/4/2007 6:39:12 PM , Rating: 2
100 000 Volts / 1000 Ohms = 100Amps

However, generally the dry skin resistance is WAY higher than that. In the range of a mega ohm.


RE: 2.5kV?
By Griswold on 1/4/2007 6:46:12 PM , Rating: 1
In theory it is 4MOhm, but as soon as a current starts to flow beneath the skin (and it will flow, especially at that voltage) the average body resistance is 1kOhm and therefore it is commonly used. Besides that, skin is almost never dry.

The example is valid.


RE: 2.5kV?
By ChronoReverse on 1/4/2007 7:11:58 PM , Rating: 2
Even so, it depends a lot on where the current is going through.

For example, high frequency AC would tend to flow over the skin. At the same time even low currents going straight through the heart will cause severe problems. Even more strange is that a bit higher (but not too much), the heart would simply stop and then restart. So it's still not a very useful example in itself.


RE: 2.5kV?
By Griswold on 1/5/2007 3:19:10 AM , Rating: 1
The 100kV example is perfectly valid because it will kill you if you're in contact with it for more than a few seconds - if you're in contact with ground potential. Of course, HV sources such as these usually have safeguards (to protect the installation, not humans) that limit the current and shut down the installation if necessary. But that is not the point here.

However, I agree with you that for low currents, its a matter of where the current is passing through. 50mA can be enough to kill a human if it is passing through the heart - and that is a fact.

At any rate, the point is, electricity is not something to joke around with and you simply do not touch conductors upwards 50V without proper safety meassures. And its grossly negligent to tell laymen something else.


RE: 2.5kV?
By masher2 (blog) on 1/5/2007 7:10:15 AM , Rating: 3
> "50mA can be enough to kill a human if it is passing through the heart..."

Even less can be fatal over an extended period of time...paralysis of the chest muscles can occur with under 20 mA. The fact remains that, as I originally said, high voltage is, in of itself , not inherently dangerous. The source has to be able to supply enough current at that voltage level to be dangerous. Ohm's Law as you orginally used it assumes an idealized voltage source of zero internal impededance, capable of supplying infinite current-- something that doesn't exist in the real world. Its a concept useful for modelling...but only so long as your load resistance remains high enough for the abstraction to remain valid.

I don't know how I can explain this any simpler. If you don't want to believe me, there are countless online references to verify against.


RE: 2.5kV?
By eetnoyer on 1/5/2007 8:40:52 AM , Rating: 2
From my own experience in high school physics. We built a tesla coil with an approximate calculated voltage of 65-75kV and noone suffered any harm from the 1" or so sparks. Unless, of course, you count the guy that was standing a little to close to the island bench and arced to the outlet from his zipper.

Not an EE, just a chemist, but have a rough understanding of the subject.


RE: 2.5kV?
By oTAL on 1/8/2007 10:11:13 AM , Rating: 2
quote:
Unless, of course, you count the guy that was standing a little to close to the island bench and arced to the outlet from his zipper.


Now he can please the ladies many times a night (batteries sold separately).


RE: 2.5kV?
By NaughtyGeek on 1/4/2007 6:45:13 PM , Rating: 2
100000 Volts/1000 Ohms = 100 Amps


RE: 2.5kV?
By DangerIsGo on 1/4/2007 9:24:59 PM , Rating: 2
quote:
ground potential - and that is most likely what you were when you touched that conductor (I assume it was one of those demonstration thingies that make your hair stand up and the like).

There is a reason why 50V (AC @50Hz) is considered the safety threshold for humans. For DC, it is 120V.


Dont you mean positive +?

And isnt it AC = 120V and DC = 50V?


RE: 2.5kV?
By Griswold on 1/5/07, Rating: 0
RE: 2.5kV?
By masher2 (blog) on 1/5/2007 6:26:54 AM , Rating: 4
> "Thus, to get away from such demonstration without burn marks, you need to stand on a insulated platform, while touching the high voltage potential."

No and no. You're probably thinking of a Tesla coil demonstration, which generates not only an extremely high voltage, but a sizeable current as well. However, there are plenty of high voltage sources which are safe, grounded or not, such as a Van der Graaf generator. Even simple static electricty sparks can go to 10kV or more....ever seen anyone die from them?




RE: 2.5kV?
By Hawkido on 1/4/2007 6:34:43 PM , Rating: 2
Higher Frequency electricity has the tendancy of moving over the surface of a conductor (your body), where lower frequency electricity takes a somewhat shorter path, occasionally cutting through the center of the conductor to get to the surface on the other side.


RE: 2.5kV?
By Griswold on 1/4/2007 6:47:25 PM , Rating: 1
Indeed. But that is in the kHz range.


RE: 2.5kV?
By MrTeal on 1/4/2007 9:41:59 PM , Rating: 2
That's assuming the device can supply 100 amps. 120/240V mains lines are dangerous because they can supply alot of current and even if they don't stop your heart, they can cause substantial burns.

A small device who's power supply is designed to provide up to say 10W at 8.5kV would have it's power supply sag well before the point it would cause damage. You'd get a nasty zap but that'd be about it.


RE: 2.5kV?
By Griswold on 1/5/2007 3:50:17 AM , Rating: 2
That was not the point. The point was mashers vague and laymen-esque description of electricity. Smattering like that can get people killed.



RE: 2.5kV?
By masher2 (blog) on 1/4/2007 11:55:43 PM , Rating: 5
> "Let's say you touch 100kV and we assume a body resistance of 1000 Ohm...we will see a current of 100mA flowing through your body (I=U/R)...It is, however, not an issue if you're properly insulated from ground potential - and that is most likely what you were "

No, you're incorrectly using Ohm's Law. In simple terms, you must realize that real-world voltages are not idealized sources, and do not remain constant regardless of load. Even in the case of 120VAC house current-- once current begins flowing, the potential drops. Voltage is measured assumming infinite resistance (or, if you prefer, zero amperage).

In the case I described, I most certainly was touching a >100kV voltage source while well-grounded, and thus current was flowing through me. A few microamps at most...which explains why I'm here typing. The reason your calculation of current was incorrect is, because the moment I touched that source, the current flow caused a corresponding potential decrease.

> "Also, ventricular fibrillation is not only a result of current flowing through your heart. Frequency is also a important factor..."

Certainly; I never said otherwise. However the fact remains that amperage is the primary factor in inducing fibrillation. Voltage is irrelevant, insofar as enough exists to overcome body resistance.


RE: 2.5kV?
By Griswold on 1/5/2007 3:45:57 AM , Rating: 1
quote:
No, you're incorrectly using Ohm's Law. In simple terms, you must realize that real-world voltages are not idealized sources, and do not remain constant regardless of load. Even in the case of 120VAC house current-- once current begins flowing, the potential drops. Voltage is measured assumming infinite resistance (or, if you prefer, zero amperage).


Now you make me smile. You are of course partly correct, but the potential drop is not nearly as big as you make it sound. Please, remain with me in reality. Ohms law is perfectly clear. The example is perfectly valid. The fact it may not occur due to technical limitations/safeguard of the voltage source does not change that.

quote:
In the case I described, I most certainly was touching a >100kV voltage source while well-grounded, and thus current was flowing through me. A few microamps at most...which explains why I'm here typing. The reason your calculation of current was incorrect is, because the moment I touched that source, the current flow caused a corresponding potential decrease.


Dont forget to mention what kind of voltage source it was. In your case, it was, most likely, a van-de-graaf generator, which generates DC (with indeed extremely low currents due to the static nature of the voltage) and thus you would not need to be insulated from ground potential. Try that with a tesla generator and report back, if you can.

quote:
Certainly; I never said otherwise. However the fact remains that amperage is the primary factor in inducing fibrillation. Voltage is irrelevant, insofar as enough exists to overcome body resistance.


Again vague and incomplete. Current is a result of voltage in your body. DC will not to the same as AC either.



RE: 2.5kV?
By masher2 (blog) on 1/5/2007 6:41:48 AM , Rating: 3
> "Now you make me smile..."

Always happy to provide a little joy in people's lives.

> "Ohms law is perfectly clear..."

It's always been so to me. The fact remains you're applying it incorrectly, by assuming idealized voltage sources. Connect a 1000 ohm resistor across a 9V battery, and you can treat that battery as an idealized source. Connect a 0.1 ohm piece of wire across the terminals, and you cannot. Many high voltage sources supply very little current, and thus to measure their voltage potential at infinity, then apply Ohm's Law using that voltage against a low resistance, gives incorrect results.

This is really pretty basic electrodynamics. And it explains why some high voltage sources, such as a static sparks, Van der Graaf generators, and the ionic generator in this article-- are all non-fatal to touch.





RE: 2.5kV?
By BladeVenom on 1/4/2007 6:25:22 PM , Rating: 2
Static electricity can be over 10,000 volts.


RE: 2.5kV?
By KaerfSusej on 1/4/2007 9:56:02 PM , Rating: 2
A static spark is about 10,000 volts per inch, though as the above stated, it has almost no amperage.


RE: 2.5kV?
By Googer on 1/5/2007 12:39:36 AM , Rating: 2
10Kv is not much. A typical static discharge on a cold morning will release about 75-100Kv or more. It's not the Voltage the causes problems for living beings, it's the amperage.

My only concern with combining ionic wind technology with electronics and computer chips is the constant preasence of static discharge that can and will destroy transistors and especially intergrated circuits (IC).


"If they're going to pirate somebody, we want it to be us rather than somebody else." -- Microsoft Business Group President Jeff Raikes

Related Articles













botimage
Copyright 2014 DailyTech LLC. - RSS Feed | Advertise | About Us | Ethics | FAQ | Terms, Conditions & Privacy Information | Kristopher Kubicki