Thursday 19 September 2013

Dual Piezoelectric Cooling Jets(DCJ) - The Cooling Technology From General Electric (GE)

As electronics get smaller, faster, and more powerful, the devices we count on in our everyday connected lives tend to get hotter, requiring some kind of cooling device. Laptops have enough room for a fan to extract heat from the CPU and memory modules, but sometimes these can become noisy.

Additionally, fans take up a lot of space, which means that the thickness of a laptop can be limited. This also means that fans are unlikely to be found in the latest in mobile computing solutions, Smartphones and tablet computers. Still, these devices also tend to heat up during use.

For years, there have been scads of applications and gizmos based on piezoelectric materials. What has most recently grabbed the attention of all is a new technology based ventilating system developed by GE Global Research.

The new cooling technology developed by General Electric based on electric cooling elements originally developed for use in jet engines promises to provide extremely compact, efficient cooling for future electronic devices.

Dubbed Dual Piezoelectric Cooling Jets, or DCJ, the system works as a system of of bellows providing high-velocity jets of air to cool components down far more efficiently than just convection alone. So far, so like the high-tech wizardry known as a 'fan' - but DCJ coolers are half the thickness and use half the energy while operating in almost complete silence.

What is a Piezoelectric Fan:
Piezoelectric, as derived from Greek root words, means pressure and electricity. There are certain substances, both naturally occurring and man-made, which will produce an electric charge from a change in dimension and vice-versa. Such a device is known as a piezoelectric transducer (PZT), which is the prime mover of a piezoelectric fan. When electric power, such as AC voltage at 60 Hz is applied, it causes the PZT to flex back and forth, also at 60 Hz.

The magnitude of this motion is very tiny, so to amplify it, a flexible shim or cantilever, such as a sheet of Mylar, is attached and tuned to resonate at the electrical input frequency. Since piezoelectric fans must vibrate, they must use a pulsating or alternating current (AC) power source. Standard 120 V, 60 Hz electricity, just as it is delivered from the power company, is ideal for this application, since it requires no conversion.

Driving the fan at resonance minimizes the power consumption of the fan while providing maximum tip deflection. The cantilever is tuned to resonate at a particular frequency by adjusting its length or thickness. The PZT itself also has a resonant frequency, so the simplistic concept of adjusting only the cantilever dimensions to suit any frequency may still not yield optimum performance. (Conceivably, tuning the electrical input frequency to match existing cantilever dimensions may work, though with the same caveat, that the resonant frequencies of all the components must match, within reason.

The Piezoelectric fans are gaining in popularity as low-power-consumption and low-noise devices for the removal of heat in confined spaces.

What is a DCJ:
The Dual Piezoelectric Cooling Jets, or DCJ consist of two pieces of metal disc with piezo elements on either size. The piezo is actuated with an AC signal, making the device pump air, much like how bellows work. Using a higher frequency, for example a few hundred Hertz, yields a substantial airflow.
The device can be scaled and modified according to application needs. The researchers tested the technology on an ultrabook laptop, replacing the cooling fan with their dual piezoelectric cooling jet.

GE touts its cooling solution as measuring just 4mm (less than a quarter of an inch), half that of existing coolers. It also runs more quietly without fan blades. These characteristics make such a system very desirable for ultraslim devices such as ultraportable laptops and tablets. The technology was originally conceived to cool jet engines (CNET got an early look at piezoelectric technology two years ago at GE Research) but it seems the company has made much progress adapting it since.

When an alternating current is passed through the ceramic component, it expands and contracts at up to 150 times per second so that the nickel discs act like a bellows. When the piezoelectric material constricts, the edges of the two nickel discs are pushed together so that they bend away from each other and suck in hot air from the surrounding area. Then, when the piezoelectric material expands, the nickel discs come together and the air is expelled from the center at high velocity.

The DCJ is running at 200hz, moves more air than a standard fan, while using less electricity, increasing battery life. The cooling jet is also quiet, which will make laptop users happy. Finally, and probably most impressive, the new cooling jet is thin enough that it could find its way into even thinner laptops or tablet computers, enhancing cooling without sacrificing weight, thickness, or silence.

Advantages of Piezoelectric DCJ:
  • Low Cost: It is developed from a inexpensive ceramic type material. It also doesn’t require any bearing as there is no rotary parts. So the operating cost is low as of Simple Circuitry.
  • Low Power & Low Noise: Power consumption is very less around 10 times less than the conventional fan. It gives a high efficiency conversion of greater than 99%. Also Operating frequency is less than 100 Hz, there by produces low noise.
  • Performance & Reliability: Can cool low power components and accommodate to low z-height. Highly reliable in performance.
  • Low Operating Voltage
  • Small in Size
  • Small Form Factor


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