With my exclusive only actual upper flow focusing Restiction zone separation experiences it has even been a bit befuddling even to me how the FEMA or a WayneKieth system could work with the low down located flow restriction plates.
I can minds eye see how the open core Mukunda’s and CPS’s work with multiple rows of cut in and out air jets following the moving heat zone boundaries up and down.
But not how this other very Un-Imbert, very Un-open core system works for the Actual Practical’s that all wood fueled systems must solve.
In exchanging here with New to woodgasification folk I always am pulled back to explaining and emphasizing that the focusing flow Restrictor hole opening is not just about hot gases flow through capabilities. It must also physically allow flow through for the created needed glowing hot char chunks and the oxidized exposed released mineral ash particles. I try and explain why maths derived from Northern European woods expereinces often fail for other world wide wood fuel bases let alone for super high ash slagging AG, and high even worse slagging high metallic’s content Urban waste fuels.
These physical solid fuels particles and ashes will be constantly wall to wall filling the gasifier hearth core areas create variable gasses flow conditions and even highly variable gasses exchange possibilities.
This first raw fuel; then semi-converted fuel ; and finally fully to woodchar converted internal physical Solids “Stack-up” has a lot of weight pushing downward that has to be supported somewhere, somehow.
Here is my Eureka.
Higher located “typical” restiction you have to pre-downsize “chew” the wood fuel chunks/particles so then with the very small amount of shinkage and breaking apart occuring in the upper zones they will be sized down small enough to pass/flow through packed “shoulder to shoulder” the focusing Restiction hole. A lot of the upper fuel particle stack weight gets hung up at this restiction point. This is actually veiwable in the systems I have operated. Easy then if hung up there, not downward flowing to NOT be able to contiously replenish the constantly shrinking gasifiacation used up lower char section and then space gap down there and allow the upper system gases to flow past unconverted into actual motor fuel gases.
In the low down located restiction systems the fuel wood chunks have more time ABOVE the restriction to heat shrink and break up smaller and smaller particle size degrading BEFORE flowing through the focus restiction opening. With more of the Stack-up solids fuel weight being intentionally restiction shelf supported, then less weight on the actual grate. And now the grate char thermal/chemical Reduction stack can be wide and shallow, continually replenished, not allowing any gapping/bypassing of the upper system gases unconverted to take place. These internal system sub-gases then Must all flow down thorough the hot activated woodchar to be into motor fuel gas conveted. This part of it IS the actual Fully REDUCED gasification and about CO2 <=> CO balances, heat energy <=> chemical energy balances conversions you want to drive to happen ONLY in the one direction before the IC engine woodgas fueling.
Ah! Ha! Click - the puzzle pieces fall into place. Solves many of the Actual Practical challenges to motor fuel woodgasifing.
And what are your woodgas Eureka moments??
Perfect. Another good post Steve (you’ve been cranking them out lately!)
My Eureka moment was to realize that gasification is a process of BURNING and UNBURNING and REBURNING. Don’t get it? Its pretty simple (and magical):
BURNING the wood: Put oxygen, wood and heat together. Flames! Smoke! Heat! The pyrolysis gas is consumed entirely.
UNBURNING the wood: The “magic” lies here. It’s the exact opposite of a normal fire. Heat is absorbed. Carbon takes “exhaust” smoke and makes it back into flammable gases - but the tars are gone.
REBURNING the wood: Send the wood (in gas form) up to the engine! Fill your cylinders and light the spark. The wood burns again, and we have power… and now the gases return to “exhaust” and smoke.
We could repeat the process, given enough heat and time. You can’t wear out CO2 or H2O. This is why charcoal gasifiers can return exhaust gases back to the gasifier, tempering the reaction and making more fuel.
For this all to work there has to be LOTS of each step happening. More char! More heat! And definitely more cylinders…
Good Morning ALL
Here is my most recent “Eureka!” moment.
More hydrogen content is commonly thought of to be “the solution” to more IC engine power . . .
actually the woodgas hydrogen is the greatest problem to IC engine running for the backfiring and derated loss of power problems over simply gasoline fueling.
Every single old woodfueled gasifier/engine operator had to deal with intake manifold/mixers Poof! backfire explosions. 20’s to 40’s. Then 50’s to 70’s. And now 80’s to current. Every single one.
With more now recent documented charcoal engine running experences now, they are asking “What’s the problem?”
Until that is they start pushing for more hydrogen with water and steam injection.
IC Engine exhaust recirculation into these doesn’t reported create the back-fire problems.
Not enough engine loaded reports yet on other charcoal gasifire added HC’s fuels like used motor oil, vegetable oils to be able to say yet one way or the other.
Then I read and re-read and excellant article that KoenVL put up about “Hydrogen in IC Engines”. Thier greatest stated problems with hydrogen fuel using in IC engines WAS pre-ignition and back-firing problems they were having to engine and engine controls design around. Thier best power equivlencies were 85% with natually aspirated/sucked in hydrogen and air versus gasoline due to the dense gasoline only having needed to occupy 1-3% of the engine cylinder volumn - the rest left for air. The much less dense, bulky gasious hydrogen for the same fuel energy needed to occupy ~37% of the cylinder volumn then displacing out much more of the needed engine combustion air. And the hydrogen fuel has a 2X more ready ability to be ignited by ANY Hot edge, Hot spark plug tip, Hot carbon deposit even from normal engine oil than gasoline! Hydrogen much more able to burn along closely following cylinder and valve edges than gasoline, methane and propane. These along with it’s 2X faster burning speed allows it to burning flame front sneek out past the partial opening and closing intake vave for those Ka-Boom intake/mixer Ka-Boom lite-offs.
Thier cylinder hydrogen/air mix filling problems were solved by Turbo/Supercharging induction; and/or liquid hydrogen injection (very inpractical except on cost plus space and millitary systems); and/or very high pressure timed directly into the cylinder hydrogen fuel injection. Not practical for us DYIers to presureze woodgas to 450 PSI for direct injection and graft into our cylinder heads direct injection ports. Doing a combination of these THEN they were able to 15% EXCEEED gasoline fuel power equivalents in the same sized engines.
BUT using these technqices then jacked up the in cylinder temperatures and presures and NOW to get thier “Lab” measured nitrous oxides California Air Resources Board required emissions down then they were having to adjust to run so fuel lean and with so much engine exhaust recirculation at 15-30% of cylinder fill volumn that thier engines were then again way down on power versus gasoline/diesel engine power equivalents in these same size of engines.
Thier recommended Solution then ?? Double oversizing the engine versus normal expected gasoline/diesel/methane/propane sizes!!!
RIGHT BACK TO WHERE WE ARE AT WOODGAS FUELING.
See . . . More hydrogen content is Not the solution.
Here are the more important Wisdoms AGAIN reinforced from the above - - -
Build and operated using an actual internal combustion engine from the get-go to get your best, most direct moving forward results into woodgas useage.
“Geeking” it one step at a time is the now the well proven failure way to woodgas develope true understanding and useabilty.
THIS IS the single greatest difference between those who got up, and are up and useable engine running in the last 30 years and those still working on flares, “perfect gas” spinning thier wheels, wasting thier’s, and others developement moneys and spending years for a S-o-m-e-d-a-y perfected results.
If you want to learn how to work horses . . . then USE HORSES.
Steve does this mean drier wood = less water gas - less water gas = less back fires?
Short answer is based on my experences yes I think so.
My expereinces have been with probably a minimum (only tested once) 12% hydrogen content to more typically later tested 18-22% hydrogen content woodgas.
Less backfires at the expense of less power potential in UNMODIFIED engines.
The majors players engine modifications I’ve been able to verify so far were use a big bore, short stroke. Long rod to stroke ratio engines. “Cylindrical” “low swirl, low turbulance combustion chamber” shaped with the piston crown dished. Flat faced or shallow dished cylinder heads with the dish edge match to the piston crown dish. Not specified; but for certain very fast opening and closing valve rates like a true “snap open”, “snap closed” low arc electrical switches. Yet cammed timed for little to no valve overlapping and high lift rises.
Look to Dustin, PeterC and Dean French as they modify engines and see what they learn.
Lots to wonder about when you have known shallow and deep hemi and penta engines been used and coming on line now. The flat heads for all of my cringing over their absolutly terrible gasses in/out flows may have been closer in the actual combustion area for the hydrogen gas componet then some of the “modern” kidney/turbulant sheer and quench turbulant combustion chamber overhead valved engine currently being done.
Back to my short answer. I will no longer be pushing for higher hydrogen content. Higher “carbonic” combustable gas and methane gas % componets yes. Take the passed through nitrogen appreciative for the hydrogen flame front tempering in the cylinder it does. And always try and keep wringing out as much gas moister pre-chamber as possible. Even this last I think will be engine type, seasonal load and heat dependent. Some unmodified stock engines sure to benfit from relitivly wet gas cooling internal hot spots to prevent hydrogen pre-ignition.
Remenber the old saying, “If it was Easy; Everyone would be doing it!”
I know I would find a place for one of my “409” chevy motors one day.
Hey DavidB and PeterC.
The 409 Chevy engine is one I’d had zero expereince with. I could see the Internet cylinder head and upper end pictures. Read the descriptions - looked real woodgas favorable alright.
Finnaly ran into and old 60’s US Forest Service mechanic expreienced with these as 348 truck engines. He said they were the only ping-less engines they ever used. Asked about the bigger 409 versions and he said for awhile as long as they had those trucks they would swap out to 409 upgrades but had to get the right ones so’s not to be forced up to premium gasoline that they did not have. These trucks were ran up and down national forest mountain roads loaded down from 1000 to 5000 feet summer and winter. Fire season now into early spring/summer snow plowing duty.
Rare birds after all of the scraping frenzy cycles. Looks like just the woodgaser trick though for HD stationary generator work.
Good Morning All
Another set of DYI personal power puzzle pieces has finnaly fallen in place for me.
2 1/2 years ago I was involed with really wringing out the loaded performance on a 5500 electrical watt Briggs and Stratton new style OHV slant cylinder gen-set woodgas fueled. Months on that project.
As the gasifier builder got better on his design and I got better on my mixer adaptation the woodgas loaded power went up. Kneeling down straddled over that 3600 RPM screeming-meemie I noticed that the engine exhaust was trending cooler and cooler under loaded engine conditions as we improved.
Did not make sence to me.
Rule of thumb is as you use more power and consume more and more HC fuel in the engine you will need to remove more waste heat out the exhaust, coolant and oil.
I ran this past different engines and expereinced alt-energy guys and they all said this should be true.
Ha! Ha! Some began to question my observations.
Well this LONG 6 months mowing season I’ve been heavily load operating two smallish different sized Honda engined rotory mowers.
The fuel is “clear” no alcohol unleaded regular gasoline.
I have been engine speed and loads adjusting to get the best ground covered done timewise with the absolute least amount of fuel used. The smaller engine is on it’s second year mowing season - upsized loaded down halfway through this eason with a 20% larger blade and deck. The other larger engine was new this year - increasing loaded, faster forced through the taller garsses and weeds. I/we bought these both new and do want them to last more than a few years.
So as air-cooled and down-speeded I have been closely monitoring the engine oil temperatures.
Ha! Same phenonmenom. As I have gotton the loads increased and the engines down RPM’s dialed in; my oil AND exhaust tenperatures have dropped with even less engine blown air flow.
I will not post up my raw numbers as having too many conditions variables in them. Black painted Honda yard and garden engine even full sun to clouds makes adifference. The trends however are clear.
Here is what I think now is happening:
These late model engines now have manufacturers optimized cylinder bore to stroke ratios. They are now cam and lift timed for the best power and (gasoline) fuel use economy with the least unburned fuel emissions. For legal sale the manufacurers are now hammered on the last - and this does get tied into to actual engine sizing ranges. And for marketing over the widest geograthical areas they must post up good numbers and capabilities. AND to sell - they must make/beat compeditive price points so adding on automotive like post engine emissions controls expenses like cats is out for them. These now even have coil pac internal ignition timing sloping based on sensed RPM. Different timing for cranking/starting; low unloaded “Idle” RPM, versus loaded RPM.
So once diealed into thier sweet spot efficiency loaded RPM ranges they are more effectivly converting the in-the-cylinder heat/pressure into shaft power.
A 33% to shaft power conversion efficient engine will have less heat needing to reject out as waste heat versus an only 23% conversion efficient engine.
This is why diesel engines for the same actual engine used power outputs have cooler exhaust streams. More heat gets turned into shaft power
So my loaded B&S cooler exhaust observation was not so much about the woodgas fuel but was more about the more modern optimized overhead valve engine able to more efficiently to shaft power convert it versus a less efficicnt flathead (valve in block) fixed timing design "freebie"engine; or the well used “cheap” OHV engines.
These are things probalbly only operator noticable on narrower RPM, fully loaded engine applications like heavy load to small engine gen-sets, light aircraft and such if you would add and watch the oil, cylinder head, coolant and exhaust temperature instrumentation.
Road vehicle guys needing wide ratio engines for acceleration and shifting would probably never notice except in the fuel consumption.
very neat observation… Thanks for the post Steve