Family of stirlings...

[n/a]

quote:Kamen hopes that his family of Stirlings, five years in development, will soon bring portable electricity to nations without a reliable power grid - or any grid at all. He envisions briefcase-sized Stirlings powering cell phones and cell towers, as well as purifying water. He aims to have them on the market in the next two years, and is currently working on the marketing issues - like how developing nations will be able to afford bulk purchases of the engines, which are projected to cost $1,500 apiece.

Staffing for the Stirling project alone involves about 20 people, including chemical, electrical, and mechanical engineers; thermodynamicists; particle and combustion physicists; and software designers and testing technicians.

http://www.wired.com/wired/archive/8.09/kamen_pr.html

I believe this is the first time Kamen's family of stirlings was mentioned or at least written about by a reporter. I wonder if all of these stirlings are intended for use on Segway or if there will be different sizes ie., with different power output or if it will also mean different types for different purposes. Eg. one for running an APU, one for charging devices like mobile phones and laptops etc. It would be interesting to get some stirling experts viewpoints on the stirling patents published so far, as to how these differ from oneanother and how their function might vary.

[ftropea]

I think the key is scalability. Let's assume, because we don't know for sure yet, that Kamen has solved the high volume manufacturing issues for his Stirling. And let's assume that each part is scalable. That means that you just have to develop cast molds for the different part, easy enough, and then put them together in an assemly plant. Maybe machines can put together the delicate components, but the engine may be the type of high volume project that gets a "Made In China" sticker on its bottom. Hope not... let's hope it's always -
"Made in the USA"!!!

Now that would explain the Metcalfe quote. And to me, that would be enough to get excited about. Now you know I really like the Segway-HT, but I'm more excited about the potential of a Stirling for consumer use.

Regards,

Frank A. Tropea
----------------------------------
Ginger : Robotics :: PC : Computers

[Seeker]

Here was a point that was made on a discussion page, devoted to discussing Stirlings :

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For some time now I have thought that a Stirling engine would be a good item for the back woods, that being defined as anyplace that does not have electricity or a ready supply of fossil fuel. My suggestion is a Stirling engine intended to be fueled by local combustibles (wood, buffalo chips, whatever). The configuration would be boxer, with a tank on the cold bank for water cooling and a firebox on the hot side. The engine itself would be magnetically coupled so there would be no shaft seal (a definite no-no in some areas). Power output would be in the 10 to 25 horsepower range, enough to do some simple farm work. To run it, just pour some water in the cold side and build a fire in the firebox. It'll run on anything that will burn. With a lot of mounting ears and flanges, it could be used for either stationary or mobile applications. Build enough safety features into it so it won't run away and disintegrate the flywheel if the load goes away. Include a reservoir for working fluid (helium?) to allow at least ten years of operation without requiring service. The idea is to provide a single box that provides mechanical power from heat. Then simplify the design, build it in the target countries to take advantage of the cheap labor and give the locals some jobs, and sell them to the guys int he back woods. The test market could be the American outdoorsman - make it into a really quiet fishing boat motor and include an alternator to provide electricity for the cabin without scaring the elk and moose away.
----------------------

I think this sounds like a great use for Stirlings : backwoods operation. If a Stirling was light enough to port around, you could bring it to where you need it, and then power it with wood ( and water).

In regards to this idea, I had a thought relating to Kamen's desire to use Stirlings in 3rd world countries. The point has been brought up that a Stirling would be costly for someone living in a 3rd world country to buy. While this is definitely true, if a Stirling were purchased by a community of people, and then used both as a portable generator (powered by wood, manure etc) and also as a water purifier, then it could be viewed as much less cost prohibitive.

It would really be mainly the initial cost which would be prohibitive, the maintenance costs would not be. I suppose this might be why Kamen's vision for using Stirlings in the 3rd world, requires investors to be involved....they would be needed to get projects 'up and running'.

Seeker

[charmed]

Sounds brilliant.

I wonder if circulating water from streams, colder than the ambiant temperature, around the cold end of it, would make the engine more efficient? No shortage of cold water in some places.

[Casey]

As I understand it, the bigger the temperature differential, the higher the efficiency. I am sure there is a limit to that, but I doubt it would be reached in this instance.

I have a spring fed pond with a year round water temperature of about 65 degrees about 4 feet deep into the water. Had it not been for the very high installation costs, I almost put in Air Conditioning cooled by this water. A stirling generator would, I think, be a great candidate for using this cold water. Being in Florida, there is no lack of sunshine, and a solar water heater panel would supply a large amount of very hot water for the "hot" end of the stirling. I believe I could supply a major part of my electrical needs using no fuel with this setup. I have also thought of concentrating sunlight directly on the "hot" end using something like a fresnel lens.

Frank

[Seeker]

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As I understand it, the bigger the temperature differential, the higher the efficiency. I am sure there is a limit to that, but I doubt it would be reached in this instance.
-----

Hi Casey,

This is my understanding as well. I also came across some interesting info from Brent Van Arsdell, on the American Stirling Company webpage :
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A good general guideline is that if the hot side of the engine is not at least 500 deg. F. (260 deg. C) the engine will be too bulky for the amount of power it puts out.
-----

Another idea I've read of recently is to use the heat from stored radioactive waste to run large Stirling engines. Along this line of thinking, I suppose that any form of waste heat, such as the hot liquid waste that is disposed of by many industries, could be used to power a Stirling. (Also,since hot waste dumped into a body of water often has a negative impact on the fish and other life forms in that water...removing the heat prior to dumping,would bring further benefits)

Seeker

[Casey]

For industrial applications I have thought of installing the "hot" end into the chimney/smokestack of such things as foundries and steel mills. That would allow the waste heat to operate the stirling as well as cool the emissions into the atmosphere. The stirling could do a number of things such as power generation to supplement the power companies supply to the factory.

Frank

[n/a]

Something I/we have overlooked from an old article mentioning the stirling:

quote:And getting a Stirling engine started takes time. The heat source can't heat the metal cylinders instantly - whereas a car engine starts immediately upon ignition. (This is why a Stirling engine can never power a car by itself.)

To accelerate the start-up, Van Arsdell said, inventors have tried attaching metal protrusions to the inside of the cylinder. The increased surface area of the hot metal maximizes the gas's exposure to the heat source. But in previous prototypes, a machinist has had to install the protrusions by hand - a time-consuming, expensive process, he said. Kamen's application suggests he's figured out a way to solve that problem by inventing a method of casting the spiked cylinders, presumably for mass production.


http://www.cmonitor.com/stories/news/recent2002/041502kamen7709%5F2002.Segway-HTml

If Van Arsdel is correct, a version of Kamen's Segway will no longer have the disadvantage of a slow start up and may therefore be usable as a powersource so that it could function as more than a battery charger. That would also make the Stirling segway much? lighter than the battery powered version and perhaps even less expensive?

[Seeker]

Charmed,

Am I reading this right, is this Saffo guy suggesting that the one wheeled Segway version that you've been talking about, and looking forward to, has already been built by Kamen ?


Saffo says the technology allowed Kamen to even develop a one-wheeled Segway -- your feet are on either side of the wheel. "The one-wheel version turns on a hill much better. I'll tell you who would be really stoked by that is the Army. You could actually create a one-wheel all-terrain vehicle with half-a-kilowatt of power."

http://atlanta.creativeloafing.com/2002-04-03/cover_news.html

[charmed]

quote:Originally posted by Seeker

Charmed,

Am I reading this right, is this Saffo guy suggesting that the one wheeled Segway version that you've been talking about, and looking forward to, has already been built by Kamen ?


Saffo says the technology allowed Kamen to even develop a one-wheeled Segway -- your feet are on either side of the wheel. "The one-wheel version turns on a hill much better. I'll tell you who would be really stoked by that is the Army. You could actually create a one-wheel all-terrain vehicle with half-a-kilowatt of power."

http://atlanta.creativeloafing.com/2002-04-03/cover_news.html







Apologies, Seeker. In trying to reply to your post, I accidently hit the 'edit' button, which explains why your post shows that it was edited by me. This moderator business is new to me, and I am realizing that a modicum of care is required.

Thanks for the link, I hadn't seen that before. It always surprises me that there is a lack of interest in discussing a single wheeled embodiment. It seems a natural progression of the technology. Not necessarily for the same applications as the two-wheeled type, but I believe that losing a wheel would open up a wide range of potential, and create some distance from the safe, staid current Segways.

If (big if) Segway is working on, or has prototypes for, a single-wheeled version, it would make a lot of sense to try and keep it hushed up for now, as it could well muck up the legislation efforts. But I maintain that it is only a matter of time before they, or someone else, introduces such a vehicle.

I maintain that it need not be absolutely stable in a lateral sense, and in fact might have performance benefits by not being DS laterally. As Paul Saffo mentions, the turning (swooping, as I imagine it) would be leaps and bounds beyond the capabilities of the double transverse wheeled embodiments.

When and if the day comes that we see a uni-wheeled version, I think we will also see an exponential rise in interest from the young, hip, and active.



Apologies for getting off topic from the stirling discussion.

[Seeker]

Actually, apologies should be mine for posting this info in the Stirling thread. I wrote the post late at night, and somehow my brain converted "family of Stirlings" into "family of Segways"...lol and that's why I had chosen this thread to post about the uniwheeled Segway, which Saffo is discussing.

Cheers and please carry on with Stirling talk in the remainder of this thread :-)

Seeker

[n/a]

U guys might want to move the Segway discussion to the appropriate threads. The topic deserves more discussion but not here. Lets keep things orderly.;) This was my first posting as moderator.[8D]

[n/a]

quote:One idea that I'm tinkering with is distributed electricity in the developing world. I'm working on a box that could burn any local fuel -- anywhere in the world -- so that electricity and clean water would be readily available to everyone, without placing a larger burden on the environment. And for the record, it's an idea that can't be fully explained in one elevator ride.
http://www.fastcompany.com/online/53/newdirection.html

a box that could burn any local fuel -- anywhere in the world

I recall reading this before, but the statement seems more clear than earlier. When u can use the cheapest, most abundant fuel sources that would mean very inexpensive electicity and clean water production.! When I read this earlier I assumed that u could perhaps modify the stirling to use one type of fuel or another. The way I read this is the above statement is that modification might not even be necessary.

As for the statement "distributed electricity in the developing world" I dont think it means for them only.

[baantjer]

quote:Originally posted by Lawrence

quote:One idea that I'm tinkering with is distributed electricity in the developing world. I'm working on a box that could burn any local fuel -- anywhere in the world -- so that electricity and clean water would be readily available to everyone, without placing a larger burden on the environment. And for the record, it's an idea that can't be fully explained in one elevator ride.
http://www.fastcompany.com/online/53/newdirection.html

a box that could burn any local fuel -- anywhere in the world

I recall reading this before, but the statement seems more clear than earlier. When u can use the cheapest, most abundant fuel sources that would mean very inexpensive electicity and clean water production.! When I read this earlier I assumed that u could perhaps modify the stirling to use one type of fuel or another. The way I read this is the above statement is that modification might not even be necessary.

As for the statement "distributed electricity in the developing world" I dont think it means for them only.


I suppose this remark is made in the context of the stirling engine/generator. I don't know how to generate the temperature difference that is needed to get an efficient stirling process with relative low energy fuel (the patents talk about burning propane).

BTW I like the remark
quote:If I have an idea that I could explain completely in an elevator, it ain't much of an idea

[don c.]

quote:Originally posted by baantjer

quote:Originally posted by Lawrence

quote:One idea that I'm tinkering with is distributed electricity in the developing world. I'm working on a box that could burn any local fuel -- anywhere in the world -- so that electricity and clean water would be readily available to everyone, without placing a larger burden on the environment. And for the record, it's an idea that can't be fully explained in one elevator ride.
http://www.fastcompany.com/online/53/newdirection.html

a box that could burn any local fuel -- anywhere in the world

I recall reading this before, but the statement seems more clear than earlier. When u can use the cheapest, most abundant fuel sources that would mean very inexpensive electicity and clean water production.! When I read this earlier I assumed that u could perhaps modify the stirling to use one type of fuel or another. The way I read this is the above statement is that modification might not even be necessary.

As for the statement "distributed electricity in the developing world" I dont think it means for them only.


I suppose this remark is made in the context of the stirling engine/generator. I don't know how to generate the temperature difference that is needed to get an efficient stirling process with relative low energy fuel (the patents talk about burning propane).

BTW I like the remark
quote:If I have an idea that I could explain completely in an elevator, it ain't much of an idea


Just a guess here, but, I think that the 'box' Kamen refers to here must be a microprocessor driven device which determines the energy density of the chosen fuel, whether propane, rice husks, wood chips, or dung; probably using infrared sensors and/or thermocouples. Perhaps the heat exchanger is mechanically adjusted according to the current fuel of choice.