Hi Goren,
Many of the DYI small woodgasifiers I’ve operated had a way to view into the heart of the Beast.
When on stationary units the single cylinder engine was very closely installed to the gasifier I also saw the char glow beat to the engine’s intake pulse.
Of course, it depended on the amount of filtering steps and cooling racks the builder had installed.
I am sure this helped to clear the char chunks of surface ash exposed.
Risky, risky to use this phenomena though . . . warming up system tars. Re-fueling cooling down tars.
Yes Tone. North America as Wallace said we once had cast iron small single engines like this too. Tall blocks. Long rods. All replaceable bearings. Special in crankcase oil holding sub-troughs for slow speed operating. None new now for 40 years.
My own thoughts going forwards for my electrical generators is to try and relieve the engine of sucking the gasifier and filter train. Instead supply the woodgas slightly pressurized delivered to the engine like done with propane and natural gas to the engine.
The woodgas; intake flow demanded from a pulsator delivery valve; delivered thru an annular ring into the air stream.
In my minds-eye I see a system similar to an electric water well house system. A pressure supply tank buffering, replenished. A modern vehicle AC system. Cycling to refill, re-pressurize upstream of the expansion orifice.
Just paper napkin speculation on my part so far. Many of my best ideas flop for an unaccounted reason on my part. Only DOing proves.
S.U.
Put your gasifier in a salvage drum
Steve
I never got around to try this drum in a drum
Approach
Separate the hot portion from the pressure barring portion and I think it’s possible to teach those high pressure values I think will improve efficiency’s
Yes i believe it’s inspired by the tesla valve, first i found about it was old ideas about tuning engines (four strokes) where the exhaust manifold should have a bigger diameter than the exhaust “holes” in the head, it gave the same effect, disturbing the back-pulse in the exhaust, less exhaust gasses blowing back in when exhaust valve closes, more evident with “evil” camshafts.
Hey guys I certainly wish there had been this active knowledgeable discussion back 10 years ago.
Just now reading this and looking now at pictures of offered up propane retrofit conversion kits onto my Harbor Freight 9500 inverter-generator I see I missed a factor. Put a cone gauze-metal screen type air cleaner on to the air-inlet side!! This will make a pulsation “wall” to reflect back from.
I did a lot 10 years ago trying to beat what a simple airbox mixer was doing.
Ha! I’ll still stand by most of what i said back then. Trying to beat the wattage out put of the simple airbox mixer pieces layed out on the white paper.
The final filter can attach picture shown to the hand-made brass throttle body was to final soot filter and pulse dampener. This was fed though a flex hose to a then remote mixer valve assembly. All, by then; brass/bronze, SS, and plastics.
Why I said be careful of your creations hanging on weights.
Mostly going forwards I take the woodgas exposure materials corrosions experiences from those 3 months winter project failure. An aversion to woodgas CO puffing back out the air mixer side into my face. And a real hate to be hovering hour after hour over an engine screaming along at 3600 RPM.
S.U.
Certainly not going to add anything knowledgeable to this discussion but despite much contemplation I still end up in the same hole. Wood gas is not like any other IC fuels. Propane and LNG are delivered pressurized from their storage container and from there the pressure can be further boosted. Because of the volume of air to fuel, gasoline or other liquid fuels can be vacuum vaporized or nozzle vaporized. Trying to pressurize WG in a plenum would require that the gas be pumped into the plenum at one point and the air metered in at another and anyway to maintain a functional stoich ratio would be daunting. Only option would possibly be direct injection of pressurized WG and a finely metered throttle body. This could all be horsecrap, but it’s the wall I keep coming up against.
It seems each time we get into a deep discussion on these little things the finer details of engine operation on woodgas, uncle tony has something to say that brings up more questions in truly optimizing a engine for woodgas.
I have several ideas about camshaft timing, valve overlap, exhaust sizing each that could be tinkered with for many miles to see how it would effect our engines. The trick I would see here in a single cylinder engine is smoothing out that valve overlap to pull a uniform mixture into the cylinder, while minimizing the intake pulse possibly using some sort of this valve you guys speak of. On top of that, for a stationary operation I think whatever is done to the motor it will be just like any other agricultural engine application meaning it will want to stabalize at some given rpm and sync to its best performance there. The issue then would be matching that rpm happy place to making clean herts power in a stable way at least for electrical generational uses
One thing more about pulsations and old Imbert’s, as we said on old Imbert’s there was always one nozzle directly in “the air-box” where the fire could be watched, and when i think about it- there’s something in the way: the back-flap valve, which in all old Imbert’s could be seen “flapping” on idle and low to middle rev’s, which maybe seems to indicate some form of “natural pulsation”?
Maybe we could stop the pulses in the gas line right there?
Then we have the problem with CO puffing back in the secondary air intake just as you mention.
Uncle Tony has good viewpoints based on his experiences.
I do always remind myself though his experiences are with liquid fuels. His experiences are with multi-cylinder engines. And these experiences applied to limited hours usages applications.
A truck and Ag/Industrial equipment engine guy will have different experiences and learned beliefs-order-of-importance.
Marine engine guys diffnertt beliefs-order-of-importance of factors
Piston aviation guy different, yet.
Tone’s; Kristijans single cylinder Ag tractors will need different engine power characteristics needs than mine, and others single cylinder fixed RPM or narrow RPM range electrical generators.
Woodgas for single cylinders I have come to believe the most important relevant factor is to relieve that only one cylinder from having to be the energy flow source for the gasifier and filter train. Multi-cylinders and you have the size and especially overlapping intake suction events to carry that power loss drag down.
Most get stuck imho on the BTU energy of woodhgas versus other engine fuels.
Once you do have enough O2 molecules to convert all of the fuel HC’s in cylinder that is enough. Simple molocule woodgas fuel components just do not need that many O2’s.
You’ve made your maximum heat and resulting in-cylinder pressure rise then. It becomes then a dynamic mechanical problem how well that engine converts these to twisting shaft power.
Medium chained HC’s dense gasoline almost always needs more O2. Long dense higher C’s chained Diesel fuels, heavy oil fuels certainly do always need more O2 than can be gotten from natural aspiration.
An engine forced to sucking a gasifier-filter train is very poor example of effective natural aspiration. It’s choking.
TomH it only takes 178 watts electricity to 100% power my made-in-China gasifer smallest blower. Enough to either blow the whole gasifier-filter train positively pressurized for enough woodgas for a smaller electrical generator. Or mid-system suck and blow pressure delivery to smaller electrical gnerators…
My larger 1200 watt continuous blowers actually only draw 500-600 watts at gasifier pressures.
So yes.
Let the engine draw in as much air as it will. Woodgas system low pressurized then blending in enough woodgas for the actual engine power needed. Maybe richer that pure stochiometric. Maybe leaner than stoichiometric.
So Yes revert back to the good 'ol bad days of the city gas plant works. Steam engine driven blowers sucking the gas plant cells. Pressure-volume lifting a water floating reservoir. Gas delivered then under a low constant pressure.
Electrical generators are/should-be always outside. More-or less stationary. No need to play the game by vehicle rules.
Electrical generators it really is mostly about the fuel use economy. While having enough power to carry the already at speed variable loadings. And do this with thousands of hours-of-service useable life.
Marine-aircraft no breakaway torque needs for them. Moderate RPM long life, absolutely dependable safe variable power. No stuck in the muds, walking back home; or, coasting to the side of the roads possible for them. Crash and break up sinking on the rocks. Crash to the ground. Splat. And maybe Burn.
Truck, Ag/Equipment’s it is 1st about get-moving break away, got-moving torque. Then speed changing power. Also demanding thousands of engine hours service life.
Racers. Hot-rodders; play a very different game. Nice guys. But myopic.
S.U.
Goren I like the tick, tick of the safety valves. Let’s me hear the rate of gas usage.
I think any pulsations made here are more beneficial for in hearth ash clearing.
I have ran gasifers with, and without on the same engine generator. I do not believe I saw a difference in a single cylinder engine performance from this factor.
Others may have different, valid experiences.
S.U.
unfortunately there just is no woodgaser folks of old that may have played these long end game runabout testing as have so many generations of hot rod culture guys. I’m sure in possibly 20’s, 30’s, 40’s there were some that really went full bore inventor in trying to design a engine that would optimize on wood/ char gas, but long dead gone and forgotten. The knowledge they would have had if given todays time materials and technology probably could have found a get around for the pulsation that plagues the single cylinder life.
To my last comment, I might add that finding that happy place of rpm use where a given single cylinder has overcome the pulsation and can have a equal enough draw through a gasfier system to maintain maybe not peak power, but peak efficiency given the fuel we use, then factors in engine longevity. Is the engine going to last a reasonable service life at that rpm? Is it oiling correctly? Cooling well enough? Todays standard of small engine life span I don’t know if in a long run it would be cost effective. These engines yall got on the other side of the pond still, we have very few of here. The consumer lifestyle of its broke junk it pay with plastic for the latest and greatest in advertisement wowee shinny sparkle just x payments of blank 99!
Grumble grumble says I… lost to the scrap yards, melted down into new Hyundai fenders. Shame shame. Enginering that was meant to last the test of time thrown out too noisy, not fuel efficient. The death of the small engine repair man not helping, few and far between they are and hard up to find the work to keep a living going with dirt cheap alternatives new and “better”
A existing engine can only be changed so much, and many unknowns of how it will effect the woodgas use. I’m sure some things can be swapped over from liquid fuels usage, we have proven timing and compression both have a drastic change for our purposes. Cylinder fill another obvious one since we always must take into account vacuum readings and resistance to flow through the system slowing flow and less cylinder fill resulting in less power. But the single cylinder struggle…the pulsation, I’m not sure it could be engineered within the engine to be gotten rid of, the valve must simply close to complete compression and ignition, the momentary stop in flow is unavoidable. Back pressure resulting.
Maybe Tony’s perspective here is best seen as a more efficient cylinder fill with tuning of exhaust port size, helping to draw out the spent gasses and draw in more new for next engine cycle. But what to do on the fuel delivery side. better brains then mine can work with this.
The simple answer, more cylinders more overlap, compensated pulsation by additional cylinders pulling pushing thins along. Kind of steps on the toes of newcomers wanting to test on lawn mower and such, they wont see the same result as a multi cylinder application and must overcome this learning curve of single cylinder use. But to this I cant speak only running my chunker a few moments on wood as my only single cylinder use, and through several variables I was not aware of not seeing the power I needed for the application. Hmmmm wish I had more experience to fall back on for this conversation.
But for my intended uses, it in some ways affirms my previous assumptions, I need a good size genny with multiple cylinders for ease of use, leaning on my multi cylinder learned knowledge as of right now till I can delve into single cylinder use more and start that other 75%
Friends, I am happy for this discussion, but I can present you my view on filling the engine, namely I intend to sacrifice some pressure, I also used this logic with the propane mixer. The propane is indeed under pressure, but the pressure regulator behind the vaporizer is underpressure, which means that the engine must create a slight underpressure for the diaphragm to let the gas into the mixer, here it is so easy to maintain the mixing ratio in all operating conditions. When preparing a mixture with wood gas, I will try something similar, the mixer will shut off the gas and air when it stops, but when the engine starts to suck, it creates some negative pressure, which overcomes the spring force and the gas enters the suction channel, and at the same time, the amount of gas must determine the amount of air. If I were to use the idea here that I tested on the propane mixer, I would have to equalize the air and gas pressure in front of the mixer. We all know that gas pressure can change from positive pressure to negative pressure, which we cannot influence, but we can influence the pressure, or negative pressure of the air. Well, the pressure loss would be a maximum of 0.05 bar or 5%, which is not much if we get a quality combustible mixture in the engine with high compression.
Someone wrote that he makes and welds a gasifier (JO) while he sleeps, but when he wakes up, he is disappointed, but I dreamed of the construction of a mixer, …
Some details: - the conical element in the middle slides along a thin axis, the spring pushes it into the seat and thus closes the gas inflow in the middle and at the same time the smaller holes for air intake in the conical seat - the pressure, or vacuum from the gas opening is transferred to a small membrane that dampens the air flow, greater vacuum - greater damping, maybe I would add a small spring here to help the membrane, this is how I would adjust and change the ratio,…
I think you will be testing a lot of different spring tensions to find just the right one and it will probably be different on different engines so I would make that housing easy to separate.
I think it won’t be difficult for Tone to find a correct spring because he already did this with his propane mixer see Gas “carbourator”.
My question is about the mass of the conical element. If there is a bump in the road will the conical element move and create a bad mixture? Perhaps we should make a very low mass conical element out of thin aluminum?
Rindert
