Thermo-electric powered tram

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Paulus
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Thermo-electric powered tram

Post by Paulus » Sun Apr 21, 2019 12:24 pm

Came across a video of a very interesting thermo-electric powered G-scale model tram on Youtube.
After some Googling I found out the build of it was described on GSC in 2016: https://www.gscalecentral.net/threads/t ... am.307351/

As far as I could see this type of alternative power was not mentioned before in this forum and although it is from 2016 I think it is still worthwhile to mention it.
It looks rather simple but I am afraid it is still a bit beyond my capacity. But perhaps it will inspire some more skilled modellers over here :idea:
At least it is much more silent than the 'diesel-electric' (nitro / methanol engine powered) models I have seen (and heard) :)


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Re: Thermo-electric powered tram

Post by Busted Bricks » Sun Apr 21, 2019 12:57 pm

It's very simple to do. Just requires a peltier element and a heatsink/fan like those used to cool CPU's in desktop PC. You heat one side of the peltier element and cool the other and it produces electricity. Efficiency is low but that's not an issue at this scale.

You can even buy elements already fitted with heat sinks. On this one you would just need to remove the smaller fan and heat that side.

https://www.banggood.com/da/TEC1-12706- ... 36497.html?

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Re: Thermo-electric powered tram

Post by Paulus » Sun Apr 21, 2019 5:54 pm

It's very simple to do. Just requires a peltier element and a heatsink/fan like those used to cool CPU's in desktop PC. You heat one side of the peltier element and cool the other and it produces electricity. Efficiency is low but that's not an issue at this scale.

You can even buy elements already fitted with heat sinks. On this one you would just need to remove the smaller fan and heat that side.

https://www.banggood.com/da/TEC1-12706- ... 36497.html?
Thank you for the your post and the link. That does seem a simple and complete device indeed.

Am I correct if I understand that the builder of the tram on the LSC forum made a construction with some sort of tubes for the cooling of the 'cool' side?
I mean, if you look at the picture of the device you linked, the big fan is cooling the 'cool' side and it is at the bottom of the first picture, right?
If you look at the pictures of the build of the tram, that same (kind) big fan is placed horizontal on the roof of the tram model and some tubes than bring air from the fan to the vertical placed 'cool' side of the element? Is that correct?


(hope I described my questions understandable enough... :scratch: )

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Re: Thermo-electric powered tram

Post by Busted Bricks » Sun Apr 21, 2019 6:12 pm

It looked liked he had found a setup where the peltier element and the cooling fins are at 90 to the hot side. The tubes transfer the heat to the peltier element. It's probably from a CPU cooling setup and convenient for his application as the hot side does not sit directly underneath the cold side. It's very underwhelming in terms of efficiency - even a solar setup on a sunny day would produce way more power. If his numbers are correct, the loco runs on only 0.375W of power which is very little.

Over on the Locobuilder Yahoo group we have been discussing a different approach - heating a steam loco with lipo battery packs. It's something I want to give a go although the opinion of most was that it would not work very well. Doesn't deter me from trying of course ;) Last summer it was VERY dry around here and I would not have felt comfortable running a gas fired loco in the garden - even an internally fired one.

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Re: Thermo-electric powered tram

Post by Paulus » Sun Apr 21, 2019 7:47 pm

Thank you for explaining.
as the hot side does not sit directly underneath the cold side.
Is it better to place it in such way that the hot side is underneath the cold side? More efficient?
heating a steam loco with lipo battery packs.

That sounds interesting as well. Please post some progress on it when you are starting with that. Would love to see how that works ;)

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Re: Thermo-electric powered tram

Post by Paulus » Mon Apr 22, 2019 7:12 am

Busted Bricks wrote:
Sun Apr 21, 2019 12:57 pm

You can even buy elements already fitted with heat sinks. On this one you would just need to remove the smaller fan and heat that side.

https://www.banggood.com/da/TEC1-12706- ... 36497.html?
Are you sure about heating the side of the smaller fan (after removing the fan)?
According to this video https://youtu.be/XtAnc-FCRpc?t=348 the side with smaller fan is the side that gets cold (ice crystals forming on it) and not hot. :scratch: :?:

According to the post on GSC the burner heats a block of aluminium which is attached to the hot side of the the heat sink. Heat is dissipated from the cold side by a heatsink.

I'm a rookie to this so... just want to make sure... ;)

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Re: Thermo-electric powered tram

Post by Keith S » Sat Apr 27, 2019 11:16 pm

Busted Bricks wrote:
Sun Apr 21, 2019 6:12 pm
It looked liked he had found a setup where the peltier element and the cooling fins are at 90 to the hot side. The tubes transfer the heat to the peltier element. It's probably from a CPU cooling setup and convenient for his application as the hot side does not sit directly underneath the cold side. It's very underwhelming in terms of efficiency - even a solar setup on a sunny day would produce way more power. If his numbers are correct, the loco runs on only 0.375W of power which is very little.

Over on the Locobuilder Yahoo group we have been discussing a different approach - heating a steam loco with lipo battery packs. It's something I want to give a go although the opinion of most was that it would not work very well. Doesn't deter me from trying of course ;) Last summer it was VERY dry around here and I would not have felt comfortable running a gas fired loco in the garden - even an internally fired one.
I think the risk of fire from an unhappy LiPo battery would be worse than from an internally fired loco. I mean the risk of either starting a fire is vanishingly small and I would be interested to see what you invent, but as you know if a LiPo cell is over-discharged or damaged, it can spontaneously ignite with an extremely vigourous fire. You'd have to have some very large batteries to create that kind of heat without over-discharging them.

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Re: Thermo-electric powered tram

Post by Busted Bricks » Sun Apr 28, 2019 12:43 pm

Over discharge will damage the cells but not cause them to catch fire as far as I know. It is over-charging that has this effect. I have a good record with Lipo cells having used them for close to 20 years. I was probably one of the first to use them in R/C aircraft, back when they would barely sustain a 1C discharge. ESC's have a low voltage cutoff that protects the cells from being discharged below a certain voltage.

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Re: Thermo-electric powered tram

Post by Melbournesparks » Sun May 19, 2019 4:25 am

Just came across this thread, might be able to answer some questions!
Paulus wrote:
Sun Apr 21, 2019 5:54 pm
Am I correct if I understand that the builder of the tram on the LSC forum made a construction with some sort of tubes for the cooling of the 'cool' side?
I mean, if you look at the picture of the device you linked, the big fan is cooling the 'cool' side and it is at the bottom of the first picture, right?
If you look at the pictures of the build of the tram, that same (kind) big fan is placed horizontal on the roof of the tram model and some tubes than bring air from the fan to the vertical placed 'cool' side of the element? Is that correct?
It uses a CPU heatsink to dissipate heat from the cool side. Lots of CPU heat sinks use "heat pipes" (I think filled with water?) to convey heat to the actual radiator fins. I luckily found one where the fins were at 90 degrees to the die block. This fits the tram application well, since it allows the fan to be mounted on the roof where there is plenty of airflow, but the actual thermoelectric unit can be mounted vertically. Since the TE unit works by temperature difference between the hot and cold side, effective cooling is important for it to work.
Paulus wrote:
Sun Apr 21, 2019 7:47 pm
as the hot side does not sit directly underneath the cold side.
Is it better to place it in such way that the hot side is underneath the cold side? More efficient?
The actual thermoelectric unit is only about 5mm thick, so the hot and cold sides are opposite each other. The best way to mount it is in a way where there will be less "leakage" of heat from the hot parts to the cool parts, which will reduce efficiency. That's why I went with a vertical mounting, it reduces the cool side being heated by convection.

The efficiency and amount of power produced is certainly low, but it doesn't take much power to move something on rails on the level. It doesn't have much in the way of gradient climbing ability though, especially since it's quite heavy! It's certainly more of a scientific curiosity than a practical mode of traction, but it is extremely simple and easy to make. There's no close tolerances or complex engineering involved, and the only fuel is the methylated spirit for the burner. The run time is really only limited by how much fuel you can carry, this one runs for about half an hour on one tank.

It should be noted that you don't actually have to use a flame for heating, since it's the temperature difference that's important. I suspect you could get a pretty long run time with a tank of hot water on the hot side, and a block of ice on the cool side. Of course eventually the water would cool down and the ice would melt, but hot water and ice can store a lot of thermal energy. You don't need to use some of the power to run a cooling fan either.

Image

It had a run yesterday for the first time in a while!

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Re: Thermo-electric powered tram

Post by Tropic Blunder » Sun May 19, 2019 1:19 pm

Was excellent to watch it trundling around the top loop yesterday mate, was excellent just to sit and watch it do its thing with a cider in hand!

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Re: Thermo-electric powered tram

Post by Paulus » Tue May 21, 2019 9:33 pm

Thank you very much for your answers Melbournesparks! That make some things clear.
I really like this tram you have build and I see the opportunities of this technique (as a 'low-tech' person).
I am serious thinking of giving it a try. Perhaps with a tea light at first or use a burner from an old gourmet set :P
Or indeed the hot water / ice method...

Would it be possible to connect 2 elements (that are both heated / cooled equal) in series to get higher voltage or parallel for more power?

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Re: Thermo-electric powered tram

Post by IanC » Wed May 22, 2019 9:17 am

Interesting project.
Ian

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Re: Thermo-electric powered tram

Post by FWLR » Wed May 22, 2019 10:39 am

Paulus wrote:
Sun Apr 21, 2019 12:24 pm
Came across a video of a very interesting thermo-electric powered G-scale model tram on Youtube.
After some Googling I found out the build of it was described on GSC in 2016: https://www.gscalecentral.net/threads/t ... am.307351/

As far as I could see this type of alternative power was not mentioned before in this forum and although it is from 2016 I think it is still worthwhile to mention it.
It looks rather simple but I am afraid it is still a bit beyond my capacity. But perhaps it will inspire some more skilled modellers over here :idea:
At least it is much more silent than the 'diesel-electric' (nitro / methanol engine powered) models I have seen (and heard) :)

Now that is a very very nice model. It's looks like it was made for the towns that had them in the past and on some heritage sites. Beamish have one in North Yorkshire, although it's not quite as quiet as your's... :roll:

Can I make a suggestion on filling your model up. If you put some mentholated spirit in a smaller bottle and then use a large syringe you can keep most of it from spilling out from the funnel. Just a suggestion hope it may help.
Rod

Life is so easy when I run my trains. :thumbright:

🚂🚃🚃🚃🚃🚃🚃🚃🚃🚃

https://gardenrails.org/forum/viewtopic ... 41&t=11364

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Re: Thermo-electric powered tram

Post by Melbournesparks » Wed May 29, 2019 12:56 am

Paulus wrote:
Tue May 21, 2019 9:33 pm
Thank you very much for your answers Melbournesparks! That make some things clear.
I really like this tram you have build and I see the opportunities of this technique (as a 'low-tech' person).
I am serious thinking of giving it a try. Perhaps with a tea light at first or use a burner from an old gourmet set :P
Or indeed the hot water / ice method...

Would it be possible to connect 2 elements (that are both heated / cooled equal) in series to get higher voltage or parallel for more power?
No worries! It's certainly simple and low tech.

You could connect as many as you like together, in theory. However there's a couple of limitations to keep in mind. The internal resistance of the elements is quite high, so connecting a few together in series will raise the no load voltage, but will limit the current. I remembered now that I did actually upgrade this tram to have two connected in series, which gives a better performance than just a single element.

The other big limitation on board a rail vehicle is effective cooling. If you add more elements, you increase the transfer of heat from the hot side to the cool side. Making the hot side hotter isn't so hard with a bigger flame, but then you have to carry the heat away from the cool side faster. So you'll reach a point where the extra power given will be cancelled out by a lower temperature difference.

There are different types of thermoelectric elements too, that have different working temperatures. The cheap ones are mostly designed for cooling, so they work best in the 0-100 degree range. I used methylated spirits to fire mine because the flame is fairly cool, so it won't melt the internal electrical connections. You can get slightly more expensive elements that are optimized for power generation that have a higher working temperature which might give better results.

That being said though, there will certainly be an optimal number and configuration of elements, and I haven't really experimented enough to find out exactly what it is! I just went with the first arrangement that works, so I'm sure with a bit of scientific experimentation the efficiency and power generation could be increased. Some radio control would be nice, but most radios require a minimum of 5v to work.

Actually just did a quick search, there are plenty of commercial small scale thermoelectric generators available these days. They're typically designed to charge USB devices at 5v DC, and some promise up to two amps! That's far more power than the tram produces, though of course they're much more expensive than assembling your self and they're not really suitable for fitting to a rail vehicle as is. Most seem to use a container of water to cool the cool side, but some have a fan for air cooling. That sort of power level is pretty much exactly what we need for rail, so it might be worth looking into to see if one could be adapted.

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Re: Thermo-electric powered tram

Post by Paulus » Sat Jun 01, 2019 11:21 am

Thanks again for your answer :)
Now I only have to find some time to experiment. But it is a thing I certainly want to try soon.

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