Log burner power

[Sunset Rising]

I must be getting old, or incredibly dim. I have read all through this thread and I do not have a clue what you are all talking about.

[blodger]

I must be getting old, or incredibly dim. I have read all through this thread and I do not have a clue what you are all talking about.

It is just about maybe making an amp or two out of a contraption attached to the stove using heat differential on some silicon chips normally used in/as the element in peltier cooling boxes. It is the Seebeck effect you are using and there are some better TEG (ThermoElectricGeneration) modules been developed to utilise that aspect rather than the Peltier heating/cooling aspects and, that can sustain working at higher temp differences and hence greater volts.

 

Commercial products (rather expensive if useful) are out there using these principles and I believe there is an energy efficient car that uses the exhaust gases with one instead of an alternator.

 

Hope that helps

 

Oh and the TEGs cost 10 times the price of the more common TEC modules; hence ecperimenting with the latter

[Sunset Rising]

It is just about maybe making an amp or two out of a contraption attached to the stove using heat differential on some silicon chips normally used in/as the element in peltier cooling boxes. It is the Seebeck effect you are using and there are some better TEG (ThermoElectricGeneration) modules been developed to utilise that aspect rather than the Peltier heating/cooling aspects and, that can sustain working at higher temp differences and hence greater volts.

 

Commercial products (rather expensive if useful) are out there using these principles and I believe there is an energy efficient car that uses the exhaust gases with one instead of an alternator.

 

Hope that helps

 

Oh and the TEGs cost 10 times the price of the more common TEC modules; hence ecperimenting with the latter

 

 

Thanks for that. Sounds bizzare. I will have to do some reading up.

 

I had been wondering about subjecting solar cells to alternative light sources as well.

[Pretty Funked Up]

Having done a fair amount of research on the subject of peltiers, there is a big discrepency between the theoretical output and what you can actually achieve.

 

In summary:

 

Whilst the rated watts quoted by the seller may be say for arguments sake 50 watts output, they hardly ever mention amps. Probably because on averge the amps are in the milliamps range i.e. not exactly very useful.

 

The amount of juice available rely on there being a large temperature diffrence between the hot side and cold side. In other words you need a very large heat sink with maybe a fan. Fans require to be powered by electricity, the same electricity being produced by the peltier!

 

Read up on thermodynamics particularly entropy. Simplistically the reason why peltiers are very efficient when powered from an external power source to produce cold - the main application - but very inefficient when wired in reverse to produce electricity.

 

Peltiers soon break down if subjected to excessive uncontrolable heat, as in attached to the side of a log burner.

 

I could be wrong i'm not an expert but from what I can make out peltier technology is a very inefficient method of producing power for anything more than illuminating an LED.

TEGs are reengineered TECs. TEC wired in reverse are useless but TEGs are where PV cells used to be 8yrs ago and getting better!

 

It is inefficient but youre missing the point. Its basically free energy that would otherwise normally be wasted. If you check the video in the original post (if its working again yet as it crashed after everyone on here tried to view it) you will see it powering a 12" tv amongst other things.

useful??? to some it most definitely is!

 

 

Adding a fan to the cold side produces around double the power than it uses and thus are a definite gain!

Edited October 31, 2010 by Pretty Funked Up

[blodger]

TEGs are reengineered TECs. TEC wired in reverse are useless but TEGs are where PV cells used to be 8yrs ago and getting better!

 

It is inefficient but youre missing the point. Its basically free energy that would otherwise normally be wasted. If you check the video in the original post (if its working again yet as it crashed after everyone on here tried to view it) you will see it powering a 12" tv amongst other things.

useful??? to some it most definitely is!

If you punch in 'TEG module' on EBay and ignore the Chinese stuff and look at the US items there are some priced at 10.63 & 3.75 p&p:-

 

Cut & Paste

Specifications

 

40mm x 40mm x 3.3mm

Operates from 0-16 volts DC and 0-10.5 amps

Operates from -60 deg C to +180 deg C

Each device is fully inspected and tested

Fitted with 6-inch insulated leads

Perimeter sealed for moisture protection

 

So these only work out at 5 times the price of the TEC modules not the 10 I had posted earlier from prices elsewhere on the web. If the experiment with TECs lights a few LEDs I'll be happy to invest in the TEGs and re-use the cheaper TECs for their cooling function elsewhere mayne not on the boat because of their consumption; nothing lost!

[Pretty Funked Up]

TEG B25-12(M) price is an amazing €399.

 

And thats me importing 100 of them.

 

The negotiation continues

[blodger]

TEG B25-12(M) price is an amazing €399.

 

And thats me importing 100 of them.

 

The negotiation continues

What wattage is that and I presume one for the stove, air or water cooled?

[Pretty Funked Up]

What wattage is that and I presume one for the stove, air or water cooled?

 

Its the one in the video and pics right back at start of thread.

its 25w - 12v , there is a charge controller involved, its not just TEGs and a heatsink.

There one on each side of the burner in the video giving 50w in total.

[Smelly]

There's a "Make" magazine article that turns up on google; the author generated 400Ma from a candle using a 37 watt TEC, if we can generate a proportional amount we're looking at 4 to 6 amps; over a day that's a lot

[Pretty Funked Up]

They wont reveal any secrets but they state:

power output,w, - not less than 25

Operationg conditions - continuous service

Lifetime not less than 10 years.

 

Presummably that means its capable of more than 25w as well!

And presummably they meant to type operating as well

Edited November 1, 2010 by Pretty Funked Up

[Alan Saunders]

They wont reveal any secrets but they state:

power output,w, - not less than 25

Operationg conditions - continuous service

Lifetime – not less than 10 years.

 

Presummably that means its capable of more than 25w as well!

And presummably they meant to type operating as well

I admire you guys, experimenting with the available technology, but it seems to me that, currently, the investment for an indvidual is out of proportion to the likely gain. OTOH, if you can invest £10K+ in TEG technology development now it may benefit the rest of us. Eventually the unit cost of the technology will reduce to a viable level and those who invested early will be ahead of the game. Beware; some who previously invested in superior technologies (e.g. Betamax etc.) lost their stake.

 

Alan S

(Frustrated Inventor)

[Pretty Funked Up]

Thanks Alan a much appreciated comment

 

I like the (frustrated inventor), then i thought hang on, did he invent betamax

 

I'll keep a dialog up with the manufacturers and see where it goes. Otherwise it's the DIY with the not so cheap TEGs and eagerly await smellys report on the cheap chinky TEGs.

 

I'm still convinced heat pipes are the way forward for the cold side! not just ya basic heatsink and fan.

Edited November 1, 2010 by Pretty Funked Up

[Roger Gunkel]

some who previously invested in superior technologies (e.g. Betamax etc.) lost their stake.

 

Alan S

(Frustrated Inventor)

 

Betamax lost out in the battle with VHS for consumer video, but because it was a better technology, the developers, Sony, increased the tape speed x6 for even higher quality and targetted the pro market under the new name of Betacam. Betacam would even record on the old Betamax tapes. The format went on to become the most successful and highly respected format ever developed for the media industry, with later Betacam SP and DigiBeta improvements. Digibeta is still being used today and is only just being replaced by newer digital formats. Far from losing their stake, Sony have reaped the rewards of one of the most successful and widely used pro tape formats for over 30 years. Betacam

 

So don't be a frustrated inventor, believe in your product

 

Roger

[bobbynell]

Investment-wise, as long as I get something that helps top up the batteries (for free) at that time of year that the solar is less viable.

 

I'm not really concerned if they take off in a big way like VHS as I'm not tying myself into ongoing costs of tapes etc.It would be fantastic if they develop as much as solar PV has over the last few years to bring the capital costs down and improve quality, but I need something right now so won't be holding my breath!

 

As the modules are so cheap I think I'll get a couple just for fun, might have a play with LEDs utilising heat from radiators or the cooker and see what they're like in practice - be eager to hear how the rest of you get on!

[Pretty Funked Up]

I think 50w can also be achieved through a flu mounted device (hot side), with heat pipes sinked to the inside of the roof (cold side) on the other side of any insulation, would be pretty similar to the water cooled ones without the need for water

[stuart]

with heat pipes sinked to the inside of the roof (cold side)

 

Would be better lower down the hull so the cold water takes the heat away.

 

I'm quite impressed with the whole idea though - good luck!

[Pretty Funked Up]

Would be better lower down the hull so the cold water takes the heat away.

 

I'm quite impressed with the whole idea though - good luck!

 

agreed but a much trickier install, already considered it Also in the peak cold months the canal is actually warmer than its surrounding. The beauty of the system is that the colder and darker it gets outside your boat the greater the output will be.

Edited November 2, 2010 by Pretty Funked Up

[stuart]

agreed but a much trickier install, already considered it Also in the peak cold months the canal is actually warmer than its surrounding. The beauty of the system is that the colder and darker it gets outside your boat the greater the output will be.

 

How much colder will the stove be if your sucking say 500W of heat out of it? Most stoves are 2-4kw ?

[Pretty Funked Up]

How much colder will the stove be if your sucking say 500W of heat out of it? Most stoves are 2-4kw ?

 

You would have to be a digital thermometer to even notice.

[blodger]

This is a 12v 12w TEG product giving an idea of size that I suppose we are looking at doing on the cheap

The only for outdoor use relates to be it being for 'spiritus or gas burner'

 

size, (lxwxh): 130x140x230 mm

weight: approx. 1.200 g.

number of thermocouples: 508

match load output power: 12 W

match load output voltage: 12 V

overheating protection through thermostat and piezo buzzer

DC-Fan: 12 V, 5000 U/min

heat flux across the heatsink: about 500 Watt

electrical connector: screw clamp

only for outdoor use.

 

item number.: M 4 01 price: on inquires

 

And another:-

 

10 watt generator

For use on burner.

 

With high-quality copper cooler, skived fin technology.

 

technical data:

 

size, (lxwxh): 100x100x80 mm.

weight: approx. 1.200 g.

number of thermocouples: 508

match load output power: 10 W

match load output voltage: 12 V

overheating protection through thermostat and piezo buzzer

DC-Fan: 92 mm, 12 V, 4000 U/min, 36 CFM

heat flux across the heatsink: about 400 Watt

electrical connector: screw clamp.

datasheet (PDF)

 

item number.: M 24 10

Edited November 2, 2010 by blodger

[blodger]

Email: tecteg@bellnet.ca

Website: www.thermoelectric-generator.com

Direct line: 905-751-1362

PRICING FOR COMPLETE TEG ASSEMBLIES

http://www.thermoelectric-generator.com/TEG2-chart.pdf

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TEG1 Charts are available @ www.thermoelectric-generator.com

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TEG1-08-12611-6.0

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TERMS: Prices Valid for 30 days from date of quote

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Quoted in USD

To order from N. America please call 1-800-769-2395

Overseas please email us at tecteg@bellnet.ca

or call 1-905-751-1362

 

Just a bit more info for the sceptics from another (rather expensive) site

[Pretty Funked Up]

Nice one, I found that site a yr or 2 ago (still poorly presented I see) but I tried and couldnt find it again recently. Thanks

 

The important bit of info i wanted to show you guys off of it was.....

 

DATA BASED ON:

Hot side 230C

Cold Side 50C

 

So you know what to aim for and you KNOW it can be done

[Alan Saunders]

How much colder will the stove be if your sucking say 500W of heat out of it? Most stoves are 2-4kw ?

Interesting. If the cold side is connected to the outside air or water this may be a significant factor. Otherwise, as with the commercial design most (99%) of the energy will be returned to the interior environment as heat. Energy efficiency ratings ignore this; e.g. if I am heating my home with electricity my 'G' rated freezer is as efficient as my electric heater as is my incandescent light bulb. As with other 'heat source' solutions (e.g. Whispergen) they are inefficient when ambient temperatures are high.

 

OTOH, If economy is the priority and fuel is cheap (e.g. found, free wood)it may be worthwhile dumping some heat to the environment. You could dump a lot of heat before you descend to the thermal inefficiency of, say, a 15Kw (20hp) engine driving a 600W alternator. Unless the waste heat is contained within the living space - unusual.

 

I so wish I had the resources to emulate the experiments detailed here. Ten years back I had the money and workshop facility (shed) to design and produce a DIY solution. Good luck to you all. If you produce a viable solution the cost of SEGs will come down and you may wish to sell your experience/expertise. The Open Source Software model may suit you. You retain the rights to your design but make them publicly available. You, and others, may then offer to supply components, assemblies, installation and support at a price.

 

If I were a 'Dragon' I would invest. But, I am not wealthy - ignore me!

 

Alan Saunders

[Smelly]

I'm curious about the heat pipe thing... Tell me more!

 

Nice one, I found that site a yr or 2 ago (still poorly presented I see) but I tried and couldnt find it again recently. Thanks

 

The important bit of info i wanted to show you guys off of it was.....

 

DATA BASED ON:

Hot side 230C

Cold Side 50C

 

So you know what to aim for and you KNOW it can be done

 

It'll be interesting to find out whether our hot plate makes those kind of temps.

 

I'm suddenly skeptical that the US TEG modules are any different from my cheapo ones; surely if they were optimised they'd be black...

[Pretty Funked Up]

I'm curious about the heat pipe thing... Tell me more!

It'll be interesting to find out whether our hot plate makes those kind of temps.

I'm suddenly skeptical that the US TEG modules are any different from my cheapo ones; surely if they were optimised they'd be black...

 

Heat pipes allow you to move heat away from its source very quickly using an advanced thermosyphon action, they will even send it down against gravity, around bends, where ever you like really. Basically having the affect of moving the cold side to somewhere errr cold rather than it being right next to the hot side.

 

OK so maybe 230 degrees is a bit high but so is 50 for the cold side, its the differential that counts really, in this case its 180 degrees. Obviously there will be more optimum temps than others, its all still so experimental at the moment, everyone is still honing the designs for performance, as am I.

 

Optimisation of the TEG is more about getting to withstand higher temps without melting/desoldering etc.

Black in colour, theres a something I hadnt thought of , but colour is more of a radient thing and we are dealing with conduction here.

Edited November 3, 2010 by Pretty Funked Up