Micro Fuel Cells

[Seeker]

Frank,

I thought this technology had some similarities to the idea you were advancing :

quote:
The new material is a superlattice - a stack of very thin films of two alternating alloys. Each layer is a few millionths of a millimetre thick, and so contains just several dozen layers of atoms. The thermoelectric effect arises here because of the many heat-absorbing or heat-radiating interfaces - it is easier for a current to flow across an interface than for heat to pass across it.

quote:
The superlattices are also effective thermal scavengers. Their large thermoelectric effect means that a significant electrical current can be induced by very small temperature differences between one side of the sandwich and the other.

http://www.nature.com/nsu/011011/011011-12.html

Seeker

[don c.]

Micro heat engine cools hot processors

By Chappell Brown

ATHENS, Ohio -- Engineers at Sun Power Inc. are engaged in an ambitious micromachine research effort that aims to shrink cooling technology to the chip level.

If the project achieves its goal, a standard CMOS IC process could be used to fabricate a Stirling cycle heat engine on a microprocessor, promising a novel cooling method for electronics. The techniques could also be used to build high-temperature superconductor chips that could be packaged in the same way as any other room-temperature circuit.

"This has the potential to explode the number of applications for cold electronics," said project originator Lyn Bowman.

more: http://www.eetimes.com/news/97/973news/micro.html

[don c.]

http://www.cea.wsu.edu/P3_PRESSRELEA...ESSRELEASE.htm

The Very Little Engine that Could

Researchers at Washington State University have built the world’s smallest engine. It would fit inside the hole of a lifesaver and is thinner than a piece of paper. This tiny engine could replace batteries in many portable electronics. The researchers in the School of Mechanical and Materials Engineering and the Center for Materials Research have received a more than $7 million contract from the Army Space & Missile Defense Command (SMDC) together with sponsorship by the Defense Advanced Research Projects Agency (DARPA) to build the engine and to produce a portable micro-power generation system for military applications. With people’s increasing dependence on portable electronics, batteries have become increasingly problematic because they weigh a lot for the power they produce. The military has struggled with this problem, so that light infantrymen are required to carry an approximately 80-pound pack in the field, with 10 pounds of that load being batteries to power their electronics. Remote-controlled airplanes and robots are limited, too, by the heavy battery packs they have to carry. The logistics of re-charging batteries can also be difficult.

The engine, dubbed the P3, for Palouse Piezoelectric Power, is radically different in design, fabrication, and operation from any existing engine. Other researchers have tried to shrink large-scale internal combustion engines down to smaller sizes. The P3 is the result of a focused effort by the WSU team to entirely rethink the concept of an engine on the micro-scale. Instead of a machine shop this engine is manufactured in a cleanroom. The engine is fabricated from silicon using the same techniques developed by the microelectronics industry. And like the integrated circuit, thousands of identical copies of the same engine may be made in a single batch fabrication process.

Each engine can stand alone or be combined with other engines providing great flexibility in choosing the power output. From the low power, long duration missions of unattended sensors, to the high power short duration missions of micro air vehicles and robots, the P3 micro engine can be reconfigured on demand to meet the needs of many applications. Effectively the P3 is the integrated circuit of engines. Just as Intel puts thousands of circuits on a chip, the WSU team aims to build multitudes of engines together to offer users power by design.

The P3 micro-heat engine also provides great flexibility in the choice of fuel or energy source. The engine could run off a variety of sources, from diesel fuel to solar energy or even waste heat. So, for example, the P3 micro engine could produce electricity from the hot surface of a computer case or an exhaust pipe.

This new type of heat engine converts thermal power to mechanical power through the use of a novel thermodynamic cycle that approaches the Carnot cycle, which gives the potential for very high efficiencies. Mechanical power is converted to electrical power through the use of a thin-film piezoelectric generator.
The engine consists of a cylinder filled with a bubble and fluid sealed at the top and bottom by thin membranes. One membrane is a thin film piezoelectric membrane generator. As heat moves into and then out of the cylinder, the size of the bubble grows and shrinks, pushing on the piezoelectric generator. The piezoelectric membrane generates electrical charge as it flexes. By combining advanced materials, engineering, and design, the WSU team has developed a totally unique engine. Because of the potential for this device, the Washington State University Research Foundation has filed for patent protection for the device developed by the researchers, David Bahr, Bob Richards, and Cecilia Richards. The researchers are continuing with testing the first prototypes.

[ftropea]

Don - just when I thought I had an original idea

Great find! You know, one thing about the Sunpower Inc. micro-Stirling is that it doesn't seem to be designed to generate electricity. It's being used more like a heat pump - either moving heat away from one area - or to an area - depending on the application. If they would make the pistons out of some magnetic material... and make the "cylinders" out of copper, for example, I wonder if that would be enough to produce electricity?

PS: Had to move this thread. I love the topic - but we're trying to keep threads in the Segway-HT forum which are directly related to the HT, and this one is "loosely" related... however, it's one of my favorite subjects.

Regards,

Frank A. Tropea

[Seg-wager]

This is fascinating! Thanks for the articles and links. Go for it, Frank!

[don c.]

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quote:
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Originally posted by ftropea

Don - just when I thought I had an original idea

Great find! You know, one thing about the Sunpower Inc. micro-Stirling is that it doesn't seem to be designed to generate electricity. It's being used more like a heat pump - either moving heat away from one area - or to an area - depending on the application. If they would make the pistons out of some magnetic material... and make the "cylinders" out of copper, for example, I wonder if that would be enough to produce electricity?

PS: Had to move this thread. I love the topic - but we're trying to keep threads in the Segway-HT forum which are directly related to the HT, and this one is "loosely" related... however, it's one of my favorite subjects.

Regards,

Frank A. Tropea

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Frank, sorry, I didn't realize there was a 'Science and Technology' forum when I posted the above. I'll probably spend more time here until Kamen can get the Seg to fly, either literally or as a consumer product!

You are right, the Sunpower stirling is not an engine or electrical generator, it is configured as a 'cyro-cooler', meaning you input energy to derive a temperature difference (most often for cooling purposes), rather than inputting a temperature differential to produce mechanical output. This is the magic of electric motors and Stirlings, they each may translate (electric or temperature differentials, depending) energy, with mechanical energy. They are 'bidirectional'.

Cooling has probably been the most important use of Stirlings to date:

"there are Stirlings that touch our daily lives. The Stirling is bidirectional, that is, if temperature difference is applied, rotation is produced. But if rotation is applied, temperature difference is produced. So the Stirling makes a refrigerator. If you go to your local welding supply company and purchase liquefied gas (such as liquefied oxygen or liquefied nitrogen), it was made in a Stirling machine. When you watch the satellite weather pictures, they are courtesy of a tiny Stirling cryocooler, used in the satellite to cool the image sensor to near absolute zero."

from: http://www.qrmc.com/stirlinginfo.html

[Casey]

I had no idea Stirlings are being used to compress gasses for bottling. I wonder what the problem is with these machines that makes them unfit as engines for generating purposes.

[don c.]

quote:Originally posted by Casey

I had no idea Stirlings are being used to compress gasses for bottling. I wonder what the problem is with these machines that makes them unfit as engines for generating purposes.

Where have you heard that they were unfit? There are a few companies producing Stirling gensets for light industrial, RV, or in-home use, and several others pursuing the technology with or without Department of Energy grants.

http://www.whispergen.com/

http://www.stmpower.com/

http://stirlingtech.com/about/index.shtml

http://www.stirlingadvantage.com/intro.htm

http://www.babcock.com/pgg/tt/pdf/E1013120.pdf

[Casey]

quote:Where have you heard that they were unfit?

It isn't anything I've heard. But if these same engines are suitable for use as heat differential engines to run generators, I fail to see what the fuss is all about concerning Kamens version of the Stirling. I have read sites concerning the use of Stirlings for various purposes, and yet there seems to be this excitement surrounding Kamens engine being a breakthrough. I deduce from that, that the Stirlings already in use are not "ready for prime time".

[ftropea]

One aspect of Kamen's Stirling that may set it aside from other Stirlings is the potential to mass produce them, inexpensively - and of course all the optimizations and design innovations that are described in his patents. One that comes to mind is that "heat transfer" array of pins or fins.. that particular part able to be cast molded for example.

Regards,

Frank A. Tropea