Stirling engines wood pellets or granules + cogeneration

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the middle
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by the middle » 12/12/09, 10:38

Hello Bernard,
I was amazed at the figure you are announcing,
The lack of vitality of stirling engines on the market shows that there is a problem, and with yields of around 15% indicated in general

Wikipedia talks about 40% efficiency.
http://fr.wikipedia.org/wiki/Moteur_Stirling
Do you have an explanation? between your figure and that of Wiki?
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bernardd
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by bernardd » 12/12/09, 14:27

Already, an explanation of the stirling engines which speaks of engines with "explosion", it is badly started with dimensions serious of the sources. This is the vocabulary of bar, not the analysis of the operation of the engines ...

I cited 15% because I have just read all the references cited in the thread, in particular the European experience in Odeillo, and this corresponds with the memories I had: we are capped at 15% in almost real conditions , because experimental.

The latest photovoltaic panels that I know, the most "efficient" overall, are those of nanosolar, without silicon, with production by printing, 3 months of return on energy investment (instead of 3 years for silicon panels), up to 16% energy efficiency in the lab, and less than $ 1 / Wp. But public release only in 2011 according to my last information :-(

But I am convinced that much more can be done with solar energy, since a piston engine normally has between 40 and 60% energy efficiency.

The poor performance of "internal combustion" engines comes from incomplete combustion in the cylinders.

A steam engine behind solar concentrators would have an overall efficiency of at least 40%. But it remains to make this engine reliably and inexpensively, in order to democratize it.
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by bernardd » 12/12/09, 14:35

By the way, the gain in pressure during the vaporization of water is the simplest explanation of the gain in efficiency obtained when water is injected with fuel or gasoline in an internal combustion engine:

the liquid water droplets vaporize by absorbing the residual heat of combustion, and increase the pressure in the cylinder, therefore on the piston, while decreasing the temperature, which is better for the engine.

You just need valves that don't rust :-)
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by chatelot16 » 12/12/09, 23:30

just because you read in wikipedia that stirling has 40% efficiency that all stirling do 40%

like all internal combustion engines, the output depends on hot and cold source temperatures: with very cold cold and very hot hot, it can actually exceed 40%: but with expensive materials for a very hot hot temperature, for a real yield of 40% temperature is required which gives a theoretical maximum carnot yield of 80%

with steam the maximum temperature is limited so the theoretical maximum yield is less good, but we obtain almost entirely this theoretical maximum: at temperatures or carnot gives 20% steam gives 18% real: steam is the best system for temperatures average
Last edited by chatelot16 the 12 / 12 / 09, 23: 41, 1 edited once.
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by chatelot16 » 12/12/09, 23:36

I do not confuse stirling and combustion engine: I just pointed out that to burn wood, boiler + thermal machine is not the best way: I prefer gasifier + internal combustion engine

even for the steam locomotive there was a locomotive where the coal hearth was replaced by a gasifier and a slightly separate burner: it really improved the performance but without application because it was done at a time when the locomotive steam had run out of time
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bernardd
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by bernardd » 13/12/09, 10:59

Hello Chatelot16, I admit that I am very curious to see one day your achievements :-)

Regarding hot gasification, I don't know. I understood that there was still a lot of "waste" that could still burn, as in gasification by fermentation.

Furthermore, the main problem with internal combustion engines is that the combustion is not good in a cylinder, simply because the ideal combustion conditions are never reached.

Finally, to have an installation that works with both direct solar heat and biomass, so that the investment is profitable, the gasification step is not obvious :-)

Personally, I arrive at an "ideal" architecture with a production of steam either by wood pellet boiler, or by solar concentrator, and a piston engine exploiting the steam pressure.

The "mechanical" energy, possibly electrical, must vary between 1 and 9KWe, with one maintenance per year and a price between 500 and 4000 €.

note: If each of the 30 million households in France produces 3KWe, the total production would be 90GWe, that is to say the peak power in France in winter. And if each of the 10 million individual houses (with more space) produces 9KW, we have the same result ...

I imagine a vapor temperature of around 500/600 ° C which should give a pressure between 80 and 90bars, but I have no precise information above, the vapor is new to me :-)

With 1m2 solar concentrators, we exceed 600 ° C, so no problem on this side ...

What do you think ?
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by chatelot16 » 13/12/09, 13:39

combustion in an internal combustion engine is much better than wood in a boiler

the mixture in an internal combustion engine is homogeneous, the temperature rises largely high enough for combustion to be complete

with the wood in a boiler if we put too much excess air we cool too much and it burns badly, if we do not put enough there is point of the hearth which lacks air and sends unburnt in the chimney

there is anyway, even with excess air production of chemical difficult to burn which leave in the smoke

the gasifier burns everything and leaves nothing useful in the ash

it produces quite dirty gas but the purification of the gas before the engine produces methanol and acetone which can be used as fuel

it's even better than cogeneration: simultaneous production of mechanical or electrical energy, heat, and liquid fuel

especially it uses green wood very well: the greener it is the more it increases the production of liquid fuel

if all the wood that is currently burned in boilers goes through this kind of gas plant, we could shut down some nuclear power plant, and mix the fuel produced to save oil

a small gasifier per house would be too complicated: a small centralization would be better: gasifier and purification of common gas for several houses, distribution of hot water to the nearest houses, distribution of gas for the houses further

no need to make too much electricity next to the gasifier because we would no longer know what to do with all the heat: it is better to distribute the gas and put small groups to cogeneration in each house

alas I have not decorated a good small combustion engine with water cooling: I use small generator with 6 hp Chinese honda imitation engine, placed directly in certain rooms to be heated and I heat other rooms by circulation hot air

it is obviously only experimental because the risk of leakage of exhaust or gas is dangerous: the solution will be to build a good small water-cooled engine well suited to this use placed outside the home

my gasifier tests are not advanced enough to serve as a model: it is much more interesting to read what was written between 1880 and 1920 when there were lots of factories and workshop powered by gasifier and engine
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by chatelot16 » 13/12/09, 13:54

bernardd wrote:I imagine a vapor temperature of around 500/600 ° C which should give a pressure between 80 and 90bars, but I have no precise information above, the vapor is new to me :-)

With 1m2 solar concentrators, we exceed 600 ° C, so no problem on this side ...

What do you think ?


attention 600 ° is beyond the critical water temperature

so anyway in a steam engine the vaporization is done in a boiler less hot than that, then there are the superheaters which can be at 600 ° but only part of the heat is exploited with the efficiency determined by 600 °

in addition it makes the pressure too strong to be practical with reasonable means

on a small scale I find the steam good for 200 or 250 ° C: the higher temperatures are precisely the damage of stirling: we can go up to high temperature and choose the pressure we want: close to atmospheric pressure if the we don't want to take a risk or a little stronger if we want to be more concentrated

as the stirling gives a yield always far enough from the theory I prefer to split the cycle in 2: stirling at 800 ° C with cold part at 200 ° C serving as a boiler for a steam engine

the steam engine has among other the advantage of being able to instantly control the power to regulate the speed of the alternator according to the demand for electricity: what stirling cannot do

having at least part of the steam cycle avoids a variable speed alternator and an inverter to make good 50hz
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by cortejuan » 02/11/12, 16:25

Hi,

I dig up this thread because I am interested in cogeneration and stirling.

Is there anything new regarding the stirling engine? In particular can we find in France in the trade, I except the stirling of demo and the toys (I of course sought but without much success).

cordially
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by dedeleco » 02/11/12, 20:08

cortejuan wrote:Hi,

I dig up this thread because I am interested in cogeneration and stirling.

Is there anything new regarding the stirling engine? In particular can we find in France in the trade, I except the stirling of demo and the toys (I of course sought but without much success).

cordially


And those claim to be the first to install them:
http://www.microcogeneration.be/Default.asp?Visited=YES

http://www.whispergen-europe.com/microc ... generacion

http://www.whispergen-europe.com/distri ... ribuidores

http://cogeneration.discutforum.com/t13 ... whispergen

http://www.econergies.org/index.php/sit ... stique_1kw

http://www.energytec.be/cogeneration-domestique.html

http://www.acqualys.fr/pages/index.php?id=469
De Dietrich marketed at the end of 2009 in the Netherlands, a 28kWth “wall-mounted” condensing boiler.


Ancient reflections:
https://www.econologie.com/forums/micro-coge ... 98-50.html


etc ...

Especially in Germany and the Netherlands outside of France !!
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