Topic: acoustic heat-engine devices to turn heat into electricity

[Nemesis]

Link to full article

Using sound to convert heat into electricity has two key steps. Symko and colleagues developed various new heat engines (technically called "thermoacoustic prime movers") to accomplish the first step: convert heat into sound.

Then they convert the sound into electricity using existing technology: "piezoelectric" devices that are squeezed in response to pressure, including sound waves, and change that pressure into electrical current. "Piezo" means pressure or squeezing.

Most of the heat-to-electricity acoustic devices built in Symko's laboratory are housed in cylinder-shaped "resonators" that fit in the palm of your hand. Each cylinder, or resonator, contains a "stack" of material with a large surface area -- such as metal or plastic plates, or fibers made of glass, cotton or steel wool -- placed between a cold heat exchanger and a hot heat exchanger.

When heat is applied -- with matches, a blowtorch or a heating element -- the heat builds to a threshold. Then the hot, moving air produces sound at a single frequency, similar to air blown into a flute.

"You have heat, which is so disorderly and chaotic, and all of a sudden you have sound coming out at one frequency," Symko says.

Then the sound waves squeeze the piezoelectric device, producing an electrical voltage. Symko says it's similar to what happens if you hit a nerve in your elbow, producing a painful electrical nerve impulse.

Longer resonator cylinders produce lower tones, while shorter tubes produce higher-pitched tones.

Devices that convert heat to sound and then to electricity lack moving parts, so such devices will require little maintenance and last a long time. They do not need to be built as precisely as, say, pistons in an engine, which loses efficiency as the pistons wear.

Symko says the devices won't create noise pollution. First, as smaller devices are developed, they will convert heat to ultrasonic frequencies people cannot hear. Second, sound volume goes down as it is converted to electricity. Finally, "it's easy to contain the noise by putting a sound absorber around the device," he says.

[Ferretlxix_XC]

Wow,  the possibilities for this is awesome. 
I guess I should start planning on my future solarpowered house after my retirement.  Along with a wind generator, I may be able to sell some power to the grid.

[Sirgod]

I'm thinking just wearing clothing like this, and possibly Picking up day to day sounds would be a major boon. Can you imagine hiking and camping, when your done for the day, plug in a battery you've been carrying, and voila, your electric gear is good for the night.

Stephen

[SkyFlyer]

The earth's crust is only a few (around 20 iirc) miles deep.

Why not bore a hole, and drop heat conductors down, and basically have steam engines creating power from the geothermal heat? You could have them anywhere, from alaska to death valley... Doesn't really matter where since the heat is the same.

[The Bar-Abbas Anomaly]

 

Good article and a great line of research.

I can't find anywhere how much electricity they're actually generating off of any of these things, though...  I would assume that it's miniscule at this stage.

[Tus-XC]

The earth's crust is only a few (around 20 iirc) miles deep.

Why not bore a hole, and drop heat conductors down, and basically have steam engines creating power from the geothermal heat? You could have them anywhere, from alaska to death valley... Doesn't really matter where since the heat is the same.

Because we've never been able to drill that deep, the deepest ever done was 7.6 miles.

[Nemesis]

The article is rather lacking in key details such as how hot it needs to get to operate efficiently.  Can it be used as an air conditioner for example?  Can it extract heat from arctic winter temperatures?

There are geothermal sources close to the surface.  Yellowstone Park houses the most famous in North America but there are others including volcanoes.

Mirrors (or fresnel lenses) could also be used to focus sunlight more intensely on the unit if higher temperatures are required.

[Tus-XC]

i actually liked the idear i read on tomshardware, using it to convert excess heat from processors into power, thus recycling it back into the system and not wasting it as heat.  one process i could forsee it being used would be to use it to extract energy from a nuclear reactors more efficiently, along side the turbines.  use them to help cool down the liquid that gets pumped around, converting it straight to electricity (though would need to be converted to AC).

[Nemesis]

The company I work for has an external cooling tower using water evaporation.  Towers such as that are good places for disease bacteria to breed.  If this can work at the same temperature ranges it could remove those towers and make maintenance work a little bit healthier. 

Cooling processes more directly (if they can be turned on and off).

Cooling exhaust vapours from smoke stacks -  while generating power. 

Solid state replacement for generators in oil, coal and nuclear plants.  Less downtime and maintenance cost and safer.

Portable non polluting generators for camping.  Since you likely have a campfire anyhow you can use these to generate power from waste heat and even cool down the ashes and charge all your battery operated devices.

Silent power for hybrid cars - no conventional engine or generator just a heat chamber and this device.

Electric motorcylce using same system as hybrid cars.

[Panzergranate]

So would it work with all the hot air generated by politicians??

I have a book here about some of the weirder inventions that have been patented in the past.

Did you know that Thomas Edison created a sewing machine powered copletely by the female voice?? And it worked!!

He noticed the noise that women make when working together. Women can't resist having a "Yak Attack!!"

He tried it out on his wife but she had to shout so hard to power it that she lost her voice for a week. A double bonus for Edison then, as it also reduced his phone bill for those weeks!!

[Sirgod]

Check this out Guys.

http://dsc.discovery.com/news/2007/05/25/soundstove_tec.html?category=technology&guid=20070525093000

May 25, 2007 — An appliance being designed for developing communities in Africa and Asia not only generates electricity, but also cooks and cools using acoustic technology.

The "Stove for Cooking, Refrigeration and Electricity," or SCORE, could help improve the health and quality of life for the two billion or so people in the world who cook over open fires. When used in enclosed places, smoke from such fires can cause health problems.

And these stoves are notoriously inefficient. A person can spend two hours a day collecting wood to burn in a fire that is so wasteful that 93 percent of the energy generated, literally, goes up in smoke.

"We make the burning more efficient so that they use less wood and have more time to spend on other things like education," said Paul Riley, the project director at the University of Nottingham in the United Kingdom.

The efficiency comes from a technology known as thermoacoustics, which produces sound waves from heated gas and then converts them to electricity.Here's how it works: wood is placed inside the stove and burned. The fire heats compressed air that has been pumped into specially shaped pipes located inside the stove's chimney and behind the stove.

The heated air begins to vibrate and produce sound waves. Inside the pipes, the noise is 100 times louder than a jet taking off. But because the pipes are stiff and do no vibrate, the sound waves have nowhere to go. So outside the pipe, people hear only a faint hum.[ page 2 of 2 ]
The sound waves vibrate a diaphragm located at the end of the pipe. The diaphragm is attached to a coil of metal wires that sit inside a magnet. As the wire coil vibrates — about 50 times per second — it generates an electrical current, which is captured by wires and converted to the proper voltage.

The stove has electrical sockets, where the homeowner can plug in, for example, a mobile phone for charging. Or she can sell the electricity as a phone-charging service.

"In Bangladesh, people could use the electricity to power lights, radio or educational equipment, for example, computers," said professor Choudhury Mahmood Hasan, chair of the Bangladesh Council of Scientific and Industrial Research in Dhaka.

For refrigeration, the heated, compressed air is sent through a different part of the pipe, where sound waves cause the air to expand. As it expands, it cools to a temperature that can produce ice. It takes about two hours of stove use to produce enough ice that will keep the fridge cold for 24 hours. But homeowners have the option of producing more ice to sell for income.

Riley and his team want to involve local universities to train a labor force that can build and manufacture most of the parts needed to make the stove. In five year's time, they hope to be churning out about 1 million stoves a year that each sell for $30 to $40.

Good stuff IMHO.

Stephen