0,7m2 as preheater is excellent as such; still the incoming airflow as cool as the (cooled) exhaustgas is only about 60 % of the outgoing gas by volume.
Tobler & Schläpfer 1937 Bern, Switzerland.
This means, that theoretically you cannot “reflow” more than about 37,5% of the outgoing gas’ heat content, however big the exchange surface.
In practice, less.
If you have a big enough cooler, the down “rinsing” condens will keep the lower part of the cooler tubes lukewarm!
And in that case the cictern should not be especially cooled; after all it has to deliver the “steam”.
This in turn, asks for the gas entering the condense cictern to be “precooled” in a meaningful way, like in the referred system.
Only practical obsticles are in you way…
Then, about the hearth, increasing the throat diameter to 3.5" and rising the grate 1" ?
Isn’t the 3" throat an insert in the “stationary” 3.5" that can simply be lifted out?
Wow! I don’t know if I’m brave enough to do both at once. Do you think I can do both without risking tar? When high ideling around the village I pull less vacuum than my little air matress blower. Or should I start with one step at a time? Which should I start with? Yes, the 72 mm is a loose insert in the 90 mm restriction, so that’s not a problem. But if I lift that out it will also increase my oxidation volume and expose more wall around nozzles. Hmmm.
If I occationally see better ratio than 5:1 it improves power very little. But worsening to 10:1 gives 50-75% of the power I get with 5:1. 5:1 seems to be a magic number to this engine. Of course it would be nice to be able to step on it without inverting guages and hayfilter, but what are the costs?
Also with higher gas flow (and a raised grate) my small coolers will have even more heat energy to handle.
What do you think?
Both! That’s to keep the active char volume near constant.
Your good air preheating should keep it going. The nozzle surroundings are the most interesting area; new charring wood does not leave this area exposed… moving char is also char!
Hearth from above, as layer after layer removed… Remember, it is the nozzle-blast which creates the fundamental heat with oxygen. The rest is to handle this heat economically for the neccessary process.
Now widening and shortening the bottom part is approaching a half ball geometry, which is “heat-economical” and low resistance… within reason!
This is a litterary theoretical expression; it just means changeing a “body’s” proportions, approaching a half ball.
Here, the running idea is to “flatten” a cylinder of char from beeing longer than the diameter to getting “square” and eventually shorter than the diameter.
Increasing diameter is here done by “exposing” the readily available stationary restriction ring just by removing the inserted inner (smaller) diameter ring.
To keep the char volume about the same, the height below the restriction must be decreased accordingly; as the mathematician you are, decreasing or increasing the diameter (squaring) matches a longer (linear) longitudial (axial) measure…
Hi JO,
I enjoyed the ride, beautiful countryside. On my way to work one day my 3 speed manual trans popped out of gear. Whoa, WT heck! Babied it a mile to a garage. Trans oil WAY down. Filled it up to level and thankfully had no problems after that.
Pepe
There are no “one-eyed” rules about that; most of these measurings are founded on imaginary flow velocities in empty hearths.
Passage by passage have norms which are founded on experience.
Also, volumes are set by experiences; they are “always” in relation to what a motor consumes under stipulated circumstancies.
That’s why all calculations go backwards to gas stream direction.
The calculating gas stream is taken from the motor, under assumed conditions.
The fundamental Reguladetri sets the “balance” between velocity, area and flow for cold@empty calculations.
Now, as the area increases, the same gas stream will pass that area slower = using more time for the passage.
l hope you will not be mad JO to post here but l wuldnt like to open a new topic for just one quick question.
I have this brake drums just begging to be used
Kristijan; I am running a gasifier using two brake drums. They are a very small insignificant part of a gasifier. The cast will take heat and not bend or distort. The Mother Earth design, they used cast iron frying pans for about the same thing. There are pictures of mine under “Tom Collins” up around 139 and 125 posting.
The important thing in building a gasifier, if using brake drums and following the Embert design is to make all of the dimension for your size engine what is shown in the Embert tables. Things which have little affect on the use of brake drums or frying pans. The diameter of the tips of the nozzles and the number of nozzles and according the hole size in the nozzles. The distance from the nozzles to the restriction and the diameter of the restriction Start thinking about the dimensions and then you can see if your brake drums will work. TomC
Thank you guys for the advices, my eyes are all red from digging the internet for dtata and calculation but l just finished reading this topic from post 1 and it occured to me l might have found the anwser for your lack of wather condensate JO.
You have stated your hopper collects 25% water by weight of wood. Is it possible it works to well? Some water is created by the combustion of wood but most gets converted to H2. At lower thain ambient pressure the evaporation is eaven stronger and the temperature… You might not have enough water in the gas to start with.
Might be the reason why you lost so much water in the condensation tank.
Hope it helps
You saw I asked that question once?
I hesitated to do that because I’ve been taught here that there is no such thing as too dry wood to a wood gasifier (plus I didn’t want Wayne’s cooler tubes look bad )
Anyway, it seems I collect 2L of hopper juice on every 6-8 kg of wood. And that wood has been stored indoors in heated space for a whole year???
Do I pull moist from nozzle air or what’s happening? Is that even possible? My nozzles are very close to the monorator recycle void (funnel void), not even 1".
Also I remember TomC once questioning the size of my wood because I was running only a 2,5" restriction at the time, but a couple of inches below the nozzles I have only pea size char ??? I don’t know, maybe that’s what it’s supposed to look like.
Moisture can come from in coming air. I don’t think your wood can ever be too dry. I’d rather the water come out in the hopper condensate catchment than have it go through the hearth. Water does and can put out fires I’m told.
Wood stored even in a heated home will probably have 8-10% moisture. That’s 8-10 Kg water to 100 Kg wood. How many L would that be? I get a headache converting.
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