Greenhouse heating invention

[SeaWalnut]

Because the greenhouse is soo tall,all the heat goes on top of it.
I got this fan wich works at 12-24 V( no danger of electric shock) and at 24 v consumes only 50 watts but its really pushing a lot of air.
Its a verry expensive fan ,EBM Papst wich new costs @ 500 dollars but i got it from the junk yard for 50 dollars only.Its brushless,can work non stop for manny years.


My idea is to link the big fan on a thermoelectric generator pannel so that it spins by using electric power made by the heat from the stove( off the grid i could say like i wouldnt need an electric socket even thogh i do have electric power ,380 v and 220 v right next to the greenhouse.
I will have to use 10 peltier modules( made in china to be cheap and TEGs not TECs- they cost @ 30 dollars) to get enough voltage to run the fan properly ,not just one as in the demonstrating picture wich shows a smaller fan.

At the end il make a nice tube from thin transparent plastic folded origami stile ,on wich the air flow from the top of the dome will be drawn to the stove by the fan,getting heated and then it will be pushed through 2 pipes that will run through the soil exiting at the oposite part from where the stove sits.
Basically will be in ground heating by air through the pipes instead of water through pipes.
The stove will be moved outdoor then,reducing the risks of fire hazards and il only have to connect the pipes that recirculate the air,the origami pipe and the in ground heating pipe.
Will also have to add rock wool insulation over the stove and pipes when il move it outdoor and what i didnt mentioned its that il have to make a metal jacket over the stove barrel to confine the airflow so that it covers the barrel entering at one end and exiting at the otther end.

[brian]

I dont follow you.  Dont peltiers consume electricity to produce a heat gradient?  Are you talking about a “seebeck generator”?

I would think youd be better off using a turbine in the exhaust flue or something to drive a fan via belt.  I imagine you will lose a lot of energy doing heat->electricity->motor

Im interested to see how it turns out though

[SeaWalnut]

I dont follow you.  Dont peltiers consume electricity to produce a heat gradient?  Are you talking about a “seebeck generator”?

I would think youd be better off using a turbine in the exhaust flue or something to drive a fan via belt.  I imagine you will lose a lot of energy doing heat->electricity->motor

Im interested to see how it turns out though

Peltier in reverse= seebeck generator.
As a generator ,these peltiers are not verry efficient,maybe 10 percent so il loose 400 watts of heat in the making of 50 watts to run the fan at full speed.
But i dont need to run the fan at full speed because thats too much and at half speed il loose @ 200 watts of heat through the peltiers to make 25 watts of power.
In indoor use the heat that peltiers uses its released back in the greenhouse so no heat its lost.
Only when il move the stove outdoor il loose that heat from the peltier/ seebeck generators but its little heat,just 200-400 watts and maybe if it will work in the chimney i might even use the little heat that i lost it anyway through the chimney.
Also in outdoor use ,the hot side of the peltiers doesnt has to be that hot as in indoor use because outdoor air in winter colder and the temp difference will be easy to mantain with lower hot side.

Normally these small generators are called Seebeck generators when you use them to produce electricity and peltiers when you fed them electricity to produce heat and cold on each side.
I wrongly name the generators peltiers instead of seebeck generators but they are the same device .
If you look at my first post you see i wrote that i will buy made in china peltiers but TEGs( thermo elctrical generators)  not TECs (thermo electrical coolers).

TEGs and TECs ,peltiers and seebeck generators are exactly the same thing just that TEGs are more expensive because they last to a slighter increased heat ,@ +150C .

[SeaWalnut]

A curiosity about peltiers its that they are used to make the invisible tank wich its invisible at night on thermal immage camera because the peltiers cool the surface of the tank and sometimes heating the tank to look like a small car or like the surroundings.

[brian]

Peltier in reverse= seebeck generator.
...
TEGs and TECs ,peltiers and seebeck generators are exactly the same thing just that TEGs are more expensive because they last to a slighter increased heat ,@ +150C .

Neat!  I didn't know this.  I realize any waste heat isn't really wasted in your case so that is a plus.

[Mark in Texas]

Because the greenhouse is soo tall,all the heat goes on top of it.

I have a HAF mounted at the top of my 6 meter high ridge which pointing down.  That's a lot of room to heat!  Have 2 mounted to the rafters to move the air clockwise.

[SeaWalnut]

 I made a tube feeder for wood wich failed ( not the one in the pictures,another one).
I filled it with wood kindling,all was working great and was selffeeding well,then i got to the shop to buy somme Coca Cola,let it to burn  not supervised and when i returned the dome greenhouse was full of smoke.
The tube got heated and the air on the exterior created a draft and it burned all the wood from the feeder indoor.
I was lucky that the greenhouse didnt caught on fire  .
But thats it.Ive had enough with these kindling and branches feeders.Next il build an auger feeder and i will buy a small wood chipper so that i will heat with wood chips.
The stainless steel keg its too small to transfer the heat in time but chilled with the fan works really great and the exhaust its really at room temperature.
Now im working on a metal jacket from verry thin aluminum plates that will cover the barrel leaving a gap in wich the air will flow to chill the barrel.
The perlite and stainless steel rebar failed because of the high temp.The stainless steel rusted after 2 weeks and the perlite clay tube was so fragile and cracked that had to be replaced with an insulated stainless steel tube.
Ive ordered somme really nice refractory blanket for the riser tube.
The Ytong brick shrinked and cracked but otther than that its doing great and whitstands the high temperatures.

From these single use plates i build the metal jacket to guide the air flow similar to a forced air colled motor cylinder ( like a Trabant ).

[SeaWalnut]

Ive made the metal jacket and put it to the test.
It works but i get the exhaust pipe hotter than when the fan was blowing directly on the top of the barrel so improvements can be made.
Im thinking at water heat teansfer next with food grade antifreeze and quit this air transfer thing.
The fan il put it to somme otther use.

[lebmung]

Im thinking at water heat teansfer next with food grade antifreeze and quit this air transfer thing.
The fan il put it to somme otther use.

A copper pipe with fins will make a better transfer. If I were you I would put the pipes in the ground and heat the greenhouse from the underfloor.
If you choose air I would put pipes through gravel underfloor. You need a thermal mass battery otherwise you will spend your whole life feeding small wood into a burner 
Your small greenhouse doesn't need to much heat. Conservation and design comes first then heating.

[spaugh]

Im thinking at water heat teansfer next with food grade antifreeze and quit this air transfer thing.
The fan il put it to somme otther use.

A copper pipe with fins will make a better transfer. If I were you I would put the pipes in the ground and heat the greenhouse from the underfloor.
If you choose air I would put pipes through gravel underfloor. You need a thermal mass battery otherwise you will spend your whole life feeding small wood into a burner 
Your small greenhouse doesn't need to much heat. Conservation and design comes first then heating.

I agree, better to pipe it to the ground and heat a few tons of rocks or something.  Use foam to insulate the heat battery from the ground. 

[SeaWalnut]

Im thinking at water heat teansfer next with food grade antifreeze and quit this air transfer thing.
The fan il put it to somme otther use.

A copper pipe with fins will make a better transfer. If I were you I would put the pipes in the ground and heat the greenhouse from the underfloor.
If you choose air I would put pipes through gravel underfloor. You need a thermal mass battery otherwise you will spend your whole life feeding small wood into a burner 
Your small greenhouse doesn't need to much heat. Conservation and design comes first then heating.

I agree, better to pipe it to the ground and heat a few tons of rocks or something.  Use foam to insulate the heat battery from the ground.

Ive quit the idea about water heat transfer too .
The next rocket stove will be outdoor ,insulated and only the horizontal chimney/exhaust will be under floor inside the greenhouse.
And the outdoor stove will have an auger ( screw) automated feeder of wood chips so il not be babysitting the stove to put wood on fire.
Also il make the stove bigger like 5 KWH since this its too small at just maximum 3Kwh wich works but i want more heat and i want the stove to burn more wood since i have a lot of wood .This one its too economic,burns verry little fuel.
I will keep it as it is to heat my workshop but for the big greenhouse it is too weak.

[SeaWalnut]

Something like this i will build next,with the chimney mounted underfloor and the rocket stove mounted outdoor,without barrel and from better materials ( refractory and steel for the fireplace and stainless steel sheet ducting for the chimney( wich will be flattened a little and put underfloor).
https://youtu.be/zul_Hdt667Y
The tall chimney at the end of the video its not necessary.It actually works a lot better without vertical chimney ,just with low ,horizontal exhaust.

[SeaWalnut]

Im thinking at water heat teansfer next with food grade antifreeze and quit this air transfer thing.
The fan il put it to somme otther use.

A copper pipe with fins will make a better transfer.

I have a lot of copper ,bronze and aluminum that i use for my artworks.
But copper its not safe to be used in a wood stove because it has too low melting point of 1080 C while a wood fire can get up ( potentially) to 1200C.Thats why you dont see copper and bronze chimneys for sale.Il use stainless steel.

On a side note,today i discovered a giant source of free wood,the river near my house wich brings in logs for free.
For phisical exercise i brought this log to my home from 2 kilometers away and it was eeally hard workout because of the slopes.The log its half rotten but heavy because its soaked in water.Found another one 3 times bigger but il have to go with the chainsaw to cut it in 3 so that we can put it on the wheelbarrow.

[brian]

If you have a boiler the pipe temperature tolerance should not be an issue as it can't go above the boiling point of water.  You could put a highly insulated wood fired boiler near the greenhouse so the piping run (and heat loss) is minimized, and if the boiler is large enough you should be able to feed it wood occasionally (1-2x daily?) and use a wax thermostat or something that doesn't require power to maintain the greenhouse temperature while the boiler temperature varies as the wood burns.

Now that I think about it, though, water may be a problem because a big fire is going to be really hot, all the water will likely boil off if you throw a bunch of logs in here.  You might need some other kind of fluid with a higher boiling point.  https://www.engineeringtoolbox.com/boiling-points-fluids-gases-d_155.html

Paraffin?  Linseed oil?  Glycerine?   Or a really large mass of water

[SeaWalnut]

Brian,ive quit the idea of water transfer.The simpler design the better.
My next rocket stove will be outdoor and the heat will go inside the greenhouse through stainless steel pipes in the floor. Like this rocket stove but outdoor and without vertical chimney ( its useless). https://youtu.be/zul_Hdt667Y

[SeaWalnut]

An old lady had a wood stove she gave me for free and i took it home,installed it in the greenhouse and im quite amazed how good it works.It is old ,a comunist era relict but has gasification ( secondary burn of the gasses) wich would probably pass even todays emission tests.
Soo well made with thick cast iron thats chromed and interior of fire bricks.A really heavy stove compared to the new ones that are buit to light enough for courier shipping.
I will keep it in the greenhouse and i will have 2 stoves,the one i will build outdoor and this small one indoor.

[Kevin Jones]

Nice find man!

Kevin

[bomjik]

Giving the fact that almost a year has passed since your last post, I would like to ask you to share with us an update on your greenhouse heating invention. I have seen all the photos you shared here, and I must say you are very talented. I wouldn't have managed to pull this through in the next 1000 years. I wonder if you have any light in that room where you've built your invention. Having high-quality ceiling lights is a must in any house, and you should take care of this, too. Anyway, wish you all the best, man, and keep posting here your inventions.