Turn Down Ratio

General Discussion
#21

Let me try to do some math/estimation…

the question would be what to measure and then use that in a calculation model.
I will try to do a first calculation , based on engine vacuum, that we all can verify/measure/use in a convenient way.

we take the vacuum between throttle valve and the engine as the value needed to calculate the degree of “filling” the engine with useable gas ( engine suction efficiency )

Since full vacuum does not exist, i assume the value at total closed throttle valve, to be 0,9 bar and the wide open throttle at 0,0 vacuum.
Further i take the max RPM , under load, at 3000 RPM WOT ( wide open throttle )
At WOT, the engine gets a max Efficiency of 0,7 (standard assumption ) and i will keep that value overall the RPM even as it is lower at higher rpm ( depending the engine )

The idlle rpm 1000 RPM

As engine we take the dakota 318 CI, equals in metric 5,2 liters

To calculate the turn down ratio, i don’t convert it into gas/air mixture because the ratio will be the same.

now at idlle rpm the engine will get 5,2 Liters / 2 * 1000 Rpm *0,7 efficiency * 0,1 ( rest from the 0,9 vacuum )
= 182 liters

At 3000 rpm WOT, the engine will get 5,2 Liters / 2 * 3000 Rpm * 0,7 efficiency * 1 ( from 0,0 vacuum)
= 5460 liters

Turn down ratio then would be 5460 to 182 or 30 to 1

Now, the above is based on assumptions and need to tested with real values, but if you where able to run your engine WOT on 3000 Rpm in perfect AFR then you would have some real power :wink:
But most likely the engine would run 3000 Rpm with max half throttle and then gets to lean.
All depending the builds from the gasifiers

If i get some data from the others, i can make a calculation model, that we all could use for our needs.

Remarks welcome

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#22

My Alzheimer’s is confusing me. I have read about “turn down ratios” for a long time but like I think we are seeing here not many people know exactly what it is. And before I try to follow through the calculations for the pounds of wood burned an hour at idle and WOT, or the air volume taken in vs the gas given off, or how large an engine a gasifier will run vs how small the same gasifier will run, I have to ask a basic question. Why do I need to know the turn-down ratio. The size shape and moisture will change the ratio. I definitely am not the scientific type that want to study all the variable to put out a paper that only another scientist could think they understand. I just want a gasifier that will give me the best performance I can obtain in daily.use. TomC

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#23

Wood gas confuzen runs grait and feels only warm too the touch on the out side unit.:innocent: fuzein me more than i like either.

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#24

TomC. and KevinR. I came back and 2dn day edited my post-up above for better readabilty. Added some expanded out explains that may help you’all.
Please re-read.
Your short vehicle use answer is in your case TomC to give your the keep-up-with-the-highway traffic you complained about not having traveling. Wayne has this. So do others. A high end turn down ratio Awareness does not overheat damaged the gasifers internals.
In both your cases a wider good-gas to bad-tarry-gas turn down ratio allows for keeping up with modern traffic and NOT then engine/system tarring/sooting up idling along through extended towns slow traffic, and idle sitting at multiple six and eight way traffic intersections.

When you cannot have the World you would wish it is still necessary to blend-in, get-along in the World you do have.
Regards
J-I-T Steve unruh

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#25

Thank you Steve for this note and for the re-write of your earlier post. I have read the earlier post 2 times in total and then dissected it into parts for more re-reads. Much better understanding of it.
The first part about stationary generators, I have little interest. ( nothing personal) I know nothing about “Ben’s Book” or any Victory gasifiers. When he was posting U-tubes I never saw one on vehicle conversions and that was my main interest. I have never tested the low end performance of my gasifier ( can’t afford to gum up an engine, to prove a point) My high end performance is “acceptable” but could always be improved. I keep trying new approaches to improve the top end and as you say optimizing one step at a time ends in a very long process, Thus every fall/spring it gets a major rebuild. If I calculate the high end capabilities, there is nothing that says a change from and to a restriction size, or nozzle circle, or pre-heating the air will get me to the max high end number. I suppose that if I knew how to calculate the high end number, I would better know if my gasifier, engine size, vehicle specs were such that I could reach higher road speeds.( PS How did you conclude that your VictoryHearth would be a tarsmakingbaby/ How do you know at what air volume pull it stops making food gas and starts making targas??) TomC

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#26

Thanks too DOW and the small car guys for the info as i am deciding how much weight too add in heat recovery and the burn tube length to my toyota 4 cyl s10 much lighter than my 2500 truck, thinking on two wall for hopper cooling similar too leitingers plan and most of the other components and knowlege from the WK book of the dakota weight range build. Flame on reverse fan fun.:dizzy_face:

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#27

Hi Kevin,

Maybe optional switching your mind into the dark side ? :grin:

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#28

Hi back TomC
In the two different VictoryGasworks shops the minimum go-too engine draw loading was a 7.5 hp Briggs and Stratton single cylinder engine on a 5500 watt generator. In both shops the go-too high end loading was a big 'ol herky trailer mounted Onan 20 kW generator set. This had a 240 CID inline six cylinder water cooled Ford industrial engine. It fan blew a hugh amount of air for an all-world/all-climates locations 100% duty cycle.
In between were different engine loading combinations like the 17kW Genrac 999cc V-twin gen set. My own Kohler 20 hp V-twin belted up to gen-heads. And the three cylinder water cooled Kubota DG1000 engined sets.

And just because it was never pictured up who’s to say my 5.0L (302cid) Ford; or BenP’s 460 (7.5L) Ford V-8’s were not used for woodgas loading, eh? Victory and APL/GEK were never about risky (legal wise) on-road vehicle operating. Nice not to have CA CARB, or WA State Ecology visiting, leaning on you. Ultimately issuing Cease and Desist Orders. Levying financial fines.

Heat overloading past top end system turndown ratio is easily seen by internal hearth heat damage. Live - I use different temp melting/burn smell emitting selected inserted bit and pieces. Just like WayneK uses paint overheating changing. And anytime any visible metal is visibly glowing you are structurally destroying that metal!! Heat overloading!! Learned this all from hard charging woodstoving.
Low end below minimum usable turndown ratio I DO BY subjective learned on the outside of the system touch/feel mostly. Knowing first what is GOOD center of range “normal” temp. Change/modify the system - and I have to relearn that system by new running experiences. “I” also do a lot of subjective learned listening to a system. Metals popping, snapping, expanding settling-in and such. Too quiet from normal experienced is too cool internally tar making.
“I” do some very subjective learned raw output gas smelling too.
You (I) can smell tars often. Good, high CO will give a mild high (and later headache); different for a CO2 woozy “feel”. Unconverted HC’s a bit acrid, mucus membranes watering. Learned this from backyard sniff “tuning” to get vehicle past tailpipe emissions inspections. Not woodgas - but vehicle Nox detected by a “happy” mood made.
Ha! Ha! I am only good for one “sampling” experience in a 24 hour period.

Do-It-Yourself is all about you; a fellow doing ALL aspects yourself.
Design, Financing, and Operation. You decide these. You balance these needs.

Not to criticize the by-the-numbers folks approach. Some for who numbers come easy, will only trust what they can number out.
And ONLY strong number people presenters will ever convince Financiers to invest big dollars into big systems investments building. And Finance people will drag in their own independent number crunching engineers before committing.

“Pinball Wizard” DIY woodgaser operator
J-I-C Steve Unruh

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#29

koen I think you meant charco gasifier, though at this point i am convinced i can breath new life into the s10 4cyl burning engine grade wood gas fuel from the WK book and afew ideas from the small car guys with the type of wood available.And with cleaner air by far on the emmission end of the spectrum.Though i do want too go charco some time later on, with a 5 horse generator engine.Thanks.My next s10 after this one will be hopefully a hi compreasion 4.3 power supply.HWWT.

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#30

Hello Steve, and All;
This is one of the most informative posts I have read from you, both personally and I think helpful to the newer members.
The first paragraph makes a great case for dynomometer testing. In the first case where you are searching for the lowest size engine, the gasifier can ruin the engine if you pass the point of the minimum the gasifier will support. That is the bad news, Several good news. Smaller engines are easier to repair. And, a good operator can watch for tel-tail, signs before “engine failure”, When hunting for the largest engine a gasifier will support, the engines is not jeopardize, any failure will be in the gasifier. And that is what you are trying to improve or perfect. My only experience with a true dyno. was in 1962 in college. We had two dyno’s that were connected together. The engine that was the object of the test was a new Chev V6 ( maybe that explains my continued interest in V6’s.) The other dyno had a Chrysler strait six. We ran the V6 through the horsepower/ rpm test and the torque/ rpm test. We SHUT OFF THE V6 IGNITION. Then we started the Chrysler but instead of hooking it to the variable electrical board, we drove the V6 using the power from the Chrysler. As our assignment, we had to add the V6 HP produced at various RPM and V6 Torque produced at various RPM and plot a combined chart which we call a “Advertised Horse Power vs Produced Horse Power” ( any errors in this paragraph is the result of the 55 years that have passed since doing it. I tried to hold the years back using “skin creams” “hair restorers” even " exercise", but I guess I was too late for the “memory restorer”.

You are putting me in a position of having to ASS-Uand ME

The first “work shop” they sponsored on wood gas was building a Fema powered '75 Chev. 3/4T (?). Then they sponsored a “road race on public roads” with one basic rule; " Complete the course in the fastest time using only one gallon of petrolium for power. Any other "powering products have to be scavengered in route. ( my interpretation of the rules ) { 55yr rule modified about 15 yr.}

I was reluctant to fill this post up with this next entire quote, but if something is worth quoting, do it right. So here is a worthy one

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#31

I wanted to bring this topic back up to the top so some of the new members could add to it if they would like :neutral_face:

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#32

Okay I will bite on this one. I read about the WW2 gasifers that when they were going down the road and going down a hill, the gasifer would cool down. They would have to keep the rpms up to prevent this from happening, or at a stop idling, the cooling gasifer could possibly start making tar, and thats not good. I recall this was a Imbert and other similar gasifer with cold air intake.
They discovered if you just heated the air up more this would help. Insulating gasifer would help. Keeping the gasifer from losing heat was the secrets of a higher turn down idling ratio and going down hills and still go down the road at a speed of 25 to 45 mph. Keeping the hearth metal hot but not so hot at WOT that metals would melt down and warp. So cast iron was used to help. This was a war effort in many countries they had thousands of people working on this. To give fuel for normal living people during war times. Many factories were built to make gasifers government monies backing them.
Now we are here and now in 2021, and where are all the factories that build gasifers they are all gone. Company or government interests in the gasification to make vehicles go down the road? Not needed.
We now travel at speeds of 75 mph. And sit in traffic idling. That was unheard of speeds of 75 for normal people of WW2 on roads back then.
Today we have gone a lot farther then our forefathers have ever done. And one man I know with a lot of “the buck stops here” determination, because he was not going to pay the high prices of fuel and it was going up, started reading books on gasification of the past. And with back yard simple tools and recycled materials figure it out where they left off, and accomplishing what they did not do back in the past. He ended up with the WK Gasifier with a high turn down ratio.
This also has happen in a lot of countries, men saying the buck stops here. And they built their improved gasification units better than the past gasifers even improving on the Imbert and many other style gasifers. Many of those men are members here on DOW
My Question is why. They knew how to do it back then , they had the resources. The answer is in many of the books they printed, that I have read on gasification.
Answer: They knew this will only be temporary soon the war will be over, so it is good enough, it will work for now to just get by. And that was it. War ended and was over back to gasoline and diesel and other fuels everyone. But not in all countries. Some hung on to those gasifers. Many were pulled of the car by orders of the government’s and many people just wanting to get them off their vehicles and go back to gasoline. Scrapping the gasifer units putting them into the junk piles to melt down.
Thank God the real inventors are not all controlled by big business and governments.
Right.
This is for the New members if you have not yet bought the book “Have Wood Will Travel” get it. It will show you the secrets of how to get good turn down ratio on your first WK gasifer build.
Bob

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