Will this Sterling heat exchange work?

[GadgetmanKen]

I'm by no means a scientist, just an inventor and I have been wondering about something for awhile. I wasn't interested in Sterlings till DK mentioned his and I got to wondering how much of a heat difference you need to kick one into operation. I heard about using all kinds of heat sources, propane, burning cow dung etc, hot rocks and cool water.. How much difference is needed? Any one know?

I was thinking and wondering if you could somehow strap a thermal body wrap, or slip on an air tight jacket or coat, with the inside warm, and then having the outside end of the Sterling exposed to the very cold, or sub zero weather. Would that be enough heat difference to run a small Sterling engine to power a small generator, or tool, etc. I mean is this something that might be possible. Any thoughts folks?

[budsiskos]

you can buy ones online that run off the heat of your hand

[Bob.Kerns]

Originally Posted by GadgetmanKen

I'm by no means a scientist, just an inventor and I have been wondering about something for awhile. I wasn't interested in Sterlings till DK mentioned his and I got to wondering how much of a heat difference you need to kick one into operation. I heard about using all kinds of heat sources, propane, burning cow dung etc, hot rocks and cool water.. How much difference is needed? Any one know?

I was thinking and wondering if you could somehow strap a thermal body wrap, or slip on an air tight jacket or coat, with the inside warm, and then having the outside end of the Sterling exposed to the very cold, or sub zero weather. Would that be enough heat difference to run a small Sterling engine to power a small generator, or tool, etc. I mean is this something that might be possible. Any thoughts folks?

This is a hard question to answer.

What do you want to do with the mechanical energy you extract from this heat differential?

I'm sure you could make a suitable Stirling-cycle engine turn -- but how much power do you have to extract to be useful for your application? How much weight is acceptable? How large a size?

Humans put out a bit over 100 W on average. You're only going to capture a small fraction of that -- maybe 10%. (Maybe more if you're willing to be very intrusive, as in a space suit. Or less.)

Of that, you may be lucky to get 20% efficiency, depending on what you're trying to do.

Is a two-watt engine useful for your purpose?

Let's say my numbers are way off, or you're willing to go to extremes. Is a 10 W engine of interest?

The current Segway headlight is 5 W -- a 10 W engine might be able to power it, after generator losses are considered.

[segsurfer]

Originally Posted by GadgetmanKen

I'm by no means a scientist, just an inventor and I have been wondering about something for awhile. I wasn't interested in Sterlings till DK mentioned his and I got to wondering how much of a heat difference you need to kick one into operation. I heard about using all kinds of heat sources, propane, burning cow dung etc, hot rocks and cool water.. How much difference is needed? Any one know?

I was thinking and wondering if you could somehow strap a thermal body wrap, or slip on an air tight jacket or coat, with the inside warm, and then having the outside end of the Sterling exposed to the very cold, or sub zero weather. Would that be enough heat difference to run a small Sterling engine to power a small generator, or tool, etc. I mean is this something that might be possible. Any thoughts folks?

It depends on the size of the Stirling, it is my understanding that as the size of the Stirling goes up, so to does the temperature variance need to run it. I don't know that much about the specifics of them either, but I've been following them since they were first mentioned to me some years back, and am pretty familiar with the basic concept. Keep in mind that in order for the Stirling to work correctly the apposing temperature chambers need to be tuned just so. But theoretically one could run off of body heat; one could say attatch a Stirling to a backpack with the back panel using your body heat for the hot side and the ambient air for the cold side. Or perhaps one could theoretically cool the system with liquid from a camelbak reservoir, perfect for keeping your beverage warm while out in the snow. All of this depends on just how small they can make the components, but it seems feasible at least in theory.
-segsurfer

[Bob.Kerns]

Stirling engines can be made very small. Or even VERY VERY small.

One application is to run a microprocessor's cooling fan from heat from the microprocessor. I haven't seen this, but I bet it's pretty small.

I've seen articles about building them on a silicon chip.

[quade]

I guess it depends on what your design goal is, but I think you'd get far greater efficiency out of powering an electric generator with your muscles.

If your design goal is to recover the energy of a human body at "rest," then I really don't think the Sterling is going to be able to recover enough energy to justify its cost and existence.

[GadgetmanKen]

I don't have a specific goal for any particular use. Not even sure if I would want to power a generator or use mechanical energy for something else. I do remember seeing a Stirling (ah.. spelled it right this time) on you tube or something running on hand heat. So with just that little heat one could power something larger with and more powerful with say a sweaty back and a really cold outside temperature. This could be small or hooked in tandem to another perhaps to generate electricity or charge something.

Or couple the orbiting /oscillating motion from it to auto shake one of those flashlight type chargers. I know its got a name but can't think what they are called just now. Faraday principle? I would have to look it up. I don't know what you could use it for at this point. What are some instances that you would need small amounts of electricity for when you are out in the really cold temps? Say walking in the snow, hunting in the cold, ice fishing, shoveling snow? You get really hot and sweaty then. I was just thinking that perhaps there could be a small personal Stiring charger of some sort that could run off of body heat and to be more efficient having the added cold from winter weather to give it a boost. I mean they are coming out with ceramic piezo type chargers for inside shoes to charge or run things why not Stirling chargers. One by product is water, albeit in this case sweaty/salty water (persperation). I don't know, someone chime in, it helps with other ideas or uses.

I was right, I surprise myself at times.

Faraday's Law of Induction explains how the relative motion of the built-in magnet sliding between metal coils charges the light's capacitor. For prolonged use, just shake for an additional 10 seconds every three minutes.

[Bob.Kerns]

If it's electricity you want, the thermoelectric effect may be more effective (certainly lighter in weight!), since you don't have two conversions going on.

I don't know -- the thermoelectric effect isn't all that efficient if I recall correctly. But often one conversion step is better than two.

The Faraday effect is also what the Segway uses to turn its wheels! (E.g. it's what makes motors work (and generators, since they're essentially the same thing). And transformers -- so the battery charger uses it, two.

[GadgetmanKen]

Or couple the orbiting /oscillating motion from it to auto shake one of those flashlight type chargers. I know its got a name but can't think what they are called just now. Faraday principle? I would have to look it up. I don't know what you could use it for at this point. What are some instances that you would need small amounts of electricity for when you are out in the really cold temps? Say walking in the snow, hunting in the cold, ice fishing, shoveling snow? You get really hot and sweaty then. I was just thinking that perhaps there could be a small personal Stiring charger of some sort that could run off of body heat and to be more efficient having the added cold from winter weather to give it a boost. I mean they are coming out with ceramic piezo type chargers for inside shoes to charge or run things why not Stirling chargers. One by product is water, albeit in this case sweaty/salty water (persperation). I don't know, someone chime in, it helps with other ideas or uses.

I guess one thing you could really use out in the cold would be hand warmers or heated ear muffs/scarfs or hats. They would not need to be constantly on. Maybe even short bursts just to take the chill out. Perhaps a coffee mug warmer. They do make nine volt battery powered heated socks and possibly gloves too.