Dual Fuel Diesel/Methane Engine

Don't have any specifics for you, but the set-up should be very close to propane fuel configuration; which should be more available in searches.

Luck!

I found some documents for liquid propane gas fuel.

But, I couldn't find anything on the setup to use a gas in an engine...

Cannot imagine how you spend 20M figuring this out? But try searching on these guys.

After 10 years and $20 million dollars of research, IMPCO Technologies is making a push to commercialize its conversion system that allows diesel engines to burn natural gas and propane.

Can't be that hard, about half the city busses run on propane.

Propane systems for gasoline engines have been a round for what, 70 some years now? I have an original system that was from a late 1940's industrial tractor and its not much different than the modern ones in use today. I have converted a Ford F250 super duty with the Triton V10 over to dual fuel with no real problems.

I also know a number of old truckers that ran propane foggers in their semis way back in the 70's and 80's! The systems as they have told me were basically just gasoline engine propane kits that were tweaked to give a different air fuel ratio so they would work more efficiently with the diesel engines.

There are a number of companies that specialize in doing the propane foggers on modern diesel pickups and big trucks today! The natural gas and hydrogen boosters for diesels use the same equipment as the propane systems but are calibrated for a different air/fuel ratio.

This is just speculation but I believe these are things to consider.

If you put the methane into the air inlet of an internal combustion engine, I suspect the mixture will ignite in the combustion chamber before the piston reaches TDC which would likely damage your engine. This is because most diesel engines have relatively high compression ratios. A little reading on the combustion properties (at what pressure vs. temperature etc.) of methane is in order.

One of the reasons gasoline to propane conversions are straightforward is that gasoline engines are low enough compression to not cause the mixture to ignite (if all is working correctly) and the ignition is started at the right time with a spark.

Actually methane and propane take far higher compression ratios to auto ignite. Not less.

Gasoline is on the low end of the compression spectrum. Most gasoline engines have less than 9:1 compression. A purpose built propane or natural gas engine can run well at around 12:1. Above that the combustion pressure can cause a more detonation type burn rate when its ignited by the spark plug. And that creates that sharp knocking that is damaging to gasoline engine components.

Both gasses wont actually auto ignite even with diesel engine compression levels under typical conditions. I have personally experimented with propane fogging a small single cylinder diesel with 18:1 compression and it will not run on propane by itself. It has to have the diesel fuel injected in order to ignite the propane. If I shut off the diesel injection pump even with the engine hot and loaded at full speed it will still not run on propane.

I have seen several large Diesel engines that were in logging machinery built in the 60's and 70's that used an actual propane burner in the air intake for cold weather starting. Volvo had one as a factory option on some of the industrial engines. It works very well too! I have even done it to farm equipment a few times myself as well. I just take the air filter out and let the engine breath in the hot flame from the big Bertha torch.

Very interesting experience. Thank you!

So would I be correct in concluding that if you wanted an engine to run on methane alone, it would be easier to start with an engine that used spark ignition?

What was the highest propane to diesel fuel ratio (by weight) you were able to use and still have reliable ignition? Do you think it was close to a stoichiometric burn?

There is no carburator in diesel engine. You can not use diesel and methane at the same time in diesel engine.

Gasoline engines can be used to handle gaseous fuels like LPG or Natural gas.

There is basic difference between diesel engine and petrol (Gasoline) engine. You need spark for gasoline engine to initiate combustion. You can use methane, natural gas, LPG etc in ""spark Ignition engine". But in diesel engine you inject diesel at the end of compression stroke when the temperature is above the autoignition temperature (because of high compression ratio). I am not aware of any system that can inject the gaseous fuels in diesel engines at such high pressure that is required to inject diesel as fuel

The coversion of gasoline engine to use natural gas or LPG is common in India since the natural gas as well as LPG are cheaper. But you can not convert diesel engine to use gaseous fuels easily, leave alone handling methane as well as diesel simultaneously.

In fact some years ago, EMD done a great deal of research in this field and did successfully modify a few of there medium speed engines (900 RPM, 1500-4000 hp +/-)to run on L.P. gas.

I had a conversation on this subject with one of the factory's senior mechanics many years ago while training.

To sum up the biggest problem, STORAGE SPACE.

They found that it was not feasible to haul the extra needed tanker type train cars to supply the fuel for a long haul.

EMD had came to rsalaskers conclusion that you couldn't simply run both fuels in the engine due to the vastly different ignition properties.

These engines were modified with spark ignitions. I don't have any factory literature available at this moment, but it would be interesting to read if anyone else has it.

Loose your "carburetor" idea, it has no place on a diesel or with gas conversions. Unless you plan to convert a carburated gasoline engine.

I read something on this some time ago, most likely on the web...

If I remember correctly, as mentioned elsewhere, you have to still inject a small amount of diesel to burn the gas on most conversions. Buses in India was one example I believe.

I also believe that the gas also needs to be injected as well.

The saving appears to be in reducing the diesel % and increasing the gas %....its also makes the engine "cleaner" if I remember correctly...

You should also pay attention to the valves as if my memory serves me correctly, burning gas can cause extra valve wear if they are are not of the correct type and style....

I'll second that.

I my area (NE USA) we have many plants (power plants and others) that use diesels that are run on gas and diesel fuel. One plant that comes to mind is Tri-gen in Trenton NJ. They normally run on 5% diesel and 95% gas.

Have you checked out Caterpillar?

Edmund

CNG is basically methane. The link below is a site that offers conversion kits, equipment but warns not all diesel engines are readily convertable.

http://www.omnitekcorp.com/altfuel.htm

There are a number of companies which make propane/diesel systems for passenger trucks and SUV's. I think Bully Dog is one, Banks Power might be another. Basically you just end up plumbing the propane line into the air intake between the filter box and the throttlebody. The propane kits usually come with a programmer so you can remap your fuel curves on the ECM after this conversion is made. I dont see why it couldnt be done with methane, but you would probably have to come up with your own custom fuel map, and Im not sure if methane will cause any emissions problems (popane kits are typically labeled for off road use only)

In fact what I'm planning to do is:

Modify a farm generator. I have biogas (with H2S) that I would treat so that would leave me mostly with CH4 and CO2. This mix is not flammable enough to ignite by itself even with the compression ratio I have of 20.6

I found information on the net saying that the diesel proportion to ignite a certain volume of biogas is 10%.

The primary goal of this project is to be able to use as much as possible the biogas of the farm. We have to use diesel, we have no choice unfortunately, but the profit in using biogas instead of diesel is non negligible.

I am planning to inject the biogas in the air intake of the engine. Therefore I have to design a carburetor to mix the right amount of biogas and air before entering the engine. That is going to require some work...

Watch yourself around that H2S... Basicaly what you will need is a regulator to control the flow of the gas being injected into the intake of your diesel engine.

Is it a two or four stroke? What are the engine specifics?

Its a 4 stroke engine with a single cylinder (0.219L), 3.3 kW and 3600 RPM.

The regulator should control the air intake so as not to inject biogaz consistently in the engine (for example when the intake valve is closed...)? How do these work?

I don't have to worry yet about the H2S as I am doing an experimental setup with just CH4 and CO2.

No, the regulator is only to regulate the flow of gas into the air intake. I use the word "regulator" loosely as you may need to refer to a valve of sorts to control the amount of gas injected in conjunction with the applied load on the engine.

Do not regulate the amount of air entering the diesel engine in any way. It's speed is regulated by the amount of fuel injected into the cylinder, not air.

Yes thank you for the information.

When I meant to regulate the air intake, I was in fact wondering about the biogas (CH4 and CO2). But even there there may not be any problems (as more air goes through the caburetor, more biogas will be in the mix... I guess).

The thing is I just want to maintain a low diesel percentage in the mix (at around 10% in volume) and regulate the power output as much as possible with the biogas. The solution I have for this would be to "jam" the fuel rod so that the minimum diesel is used and the rest of the required power will be supplied by the biogas.

But for light loads, I just have to change the diesel injection (to have less diesel in the engine) ... there is a lot of control there.

As your engine (it would really help to know exactly which), surely is equipped with a governor; the more gas you inject/the less fuel your governor will be sending to the injector.

I hope that makes sense....

Getting back to basics of the diesel engine, air is completely unrestricted and the governor regulates a set speed by injecting (or rather controlling the injection) of more or less fuel as required to maintain the set speed.

Now... If your gas is introduced into the intake air, less fuel will be needed and the governor will in effect back down on the fuel while the engine maintains its set speed.

Be careful that you do not send too much gas as you could damage your engine in many different ways, some of them being;

• Overspeed (as the gas is not controlled through the governor)
• Valve or cylinder damage (as the diesel also acts as a lubricant)

sorry about that, I forgot to put the link to my engine (yanmar L48V)

http://www.yanmar.com/store/item.asp?ITEM_ID=52&DEPARTMENT_ID=62

Thats a tough little engine for your experiment... As basic as it gets, good luck.

I live in the Philippines. I have a small Gen set 8 KW air cooled diesel. How did you go with your tests?

Cheers,

Gus

Hi, I am just going on with the tests, I finally injected the biogas in the air intake of the engine. I find some astonishing results (like having more power output when I replace 50% of diesel) so I have to go on with the tests and see how it goes. Regards

How did you replace 50% of the diesel??? It is not clear what you are trying to tell us.....

Sorry for the late reply, but in fact i just limited the injection throttle to half its maximum injection (with a simple screw making it impossible to turn past this screw).

And the rest of the power was coming from the biogas I was injecting in the air intake of the engine.

Back about a bazillion years ago when I was a young Seabee, we had numerous engines which were designed for multifuel operation. They would run just fine on regular gasoline, diesel fuel, jet fuel (JP5) or even peanutbutter if you could get it liquid enough to flow. You might try to find info on some of those old military multifuel engines.

The CO2 in your gas will restrict the flammability range of your mixture, as you are dosing the inlet charge with a proportion of inert gas.

If you have plenty of water, you could try scrubbing the gas with water to dissolve some of the CO2 and almost all the H2S. The waste water could then be used to irrigate the garden, so the scrubbed components aren't lost neither is the water wasted.

You may want to adapt a car fuel injection system (port type) and try preheating your gas by using exhaust heat.

This won't significantly heat the air charge, but will make the gas more readily ignited, enabling the diesel required to be cut back further, especially when at part load.

This injector could then be controlled as part of the governor circuit.

Most generating plants spend the majority of their time running lightly loaded. The lack of lubricity of the gas and the requirement for a minimum diesel quantity to permit ignition could mean that under light load it will have to work almost entirely with diesel.

You have some experimenting ahead of you to make it work, but the idea has possibilities.

Good luck

Thanks for all this information.

I have read that H2S is soluble in water (0.5g of H2S per 100mL of water at 67°F or http://www.engineeringtoolbox.com/gases-solubility-water-d_1148.html ) and about CO2 as well ( http://jcbmac.chem.brown.edu/myl/hen/CO2Water.gif )

This made me think I just make the biogas go through a water tank before being injected in the engine.

As for heating the engine, I can take it in consideration because the remaining molecules of H2S form SO2 which then condensates to sulfuric acid in contact with liquid water. Heating the engine would prevent formation of liquid water.

You seem to have some experience with H2S, have you done any experiment with biogas?

Hi guy's, I haven't been around as much as I used to on CR4 with a bunch of life going on. This is an area in which I've studied greatly for many years now. This summer in fact, I will be attending a class at MIT in July and hope to be discussing some information related with Dr. Heywood and Dr. Cheng. There are many around the world testing and devising many and appropriate methods in which to utilize different fuels with existing diesel and SIE's as I have.

I won't get into a ton of details here but developing means to make diesel and SIE more efficient is just plane necessary. Bringing them to utilize different available fuels is long since past, and has been done. Read "the Romance of Engine" by Dr. Takashi Susuki. Hino had accomplished similar many years ago including increasing adiabatic efficiencies. http://www.amazon.com/Romance-Engines-R-188-Takashi-Suzuki/dp/1560919116 I won't begin to get into the regulations and government red tape that hinders real production in these area in terms of bringing well tested devices into the market place. Many devices or systems developed either at universities or labs, as I have realized here at Sandia or Los Alamos, rarely see the light of day much less a market. So what you see in the market place now is whats available. However much has been around like one guy said for over 70 years without much improvement in my opinion.

Keep experimenting and utilize it for your own gain. I like many other engineers, inventors, scientists etc, am about fed up with a lot of work that goes into this development to end up no where. At least in my case I'm not bound by a contract with a federal agency regarding proprietary information. Mean while there is some amazing devices developed that are just not going to get out of the prototype stages.

So, I'm not trying to be a buzz kill here, just offering some encouragement. "They" can't take away my desires to learn more and develop more ideas and implement them to some degree, so far anyway. So good luck with all your research in this area. Keep working on it you'll figure it out and a way to make it work for your needs!

The problems that you suggest fixes for are (if I remember correctly!) are to do with the fact that certain gases are far less likely to self ignite that even the highest grades of petrol for example......

I would also like to say to the OP the following ideas of mine on this subject:-

I have no experience in this area, but may I suggest that injecting (via its own injector in the head) the gas either just before or even at the same time as the diesel may be the best (if somewhat mechanically problematic) idea......the idea of putting gas in the intake tract, which might work (or not) appalls me, it could easily escape and cause a fire.....lots of extra controls will be needed.....efficiency will also be reduced as if gas is brought in this way, as there will be less air......a very important point!

A Diesel engine needs to intake as much air as possible, which is why, when fitted, a Turbo aspirated Diesel has significantly higher efficiencies than normally aspirated ones. The Turbo simply compresses more air into the engine at the same time removing otherwise lost energy from the exhaust gases......a "win win" situation.

I just had a thought, if you could design a a unit that could use the injector hole already in the head and aldo take the original injector and a new one for gas, you might save yourself a lot of problems......

I hope this gives you a few more good ideas....

All around great advice.

I don't actually think the lubricating property of diesel is needed as far as I know. The piston designs typically have a much higher crank case oil flow associated with them in order to keep them cooler than what is used in a gasoline engine. As far as vapor fuel are concerned they actually greatly increase the engine life simply because they have very little soot production and almost no cylinder wall wash down effects.

The only possible thing would be if the engine has an unusually high exhaust temperature then the exhaust valve and seat my need to be made of a harder material. But being a single cylinder air cooled I assume , the valves and seats are all ready hardened to hold up to the higher head temperatures associated with air cooled engine designs.

My little Petter diesel is similar to yours and I have had a lot of fun messing around with non conventional fuels. I have had great results running pure used oil as a fuel. However there is a flow problem associated with the thick oils when no preheating is used, but using a roughly 10% mix of E85 seems to work well in getting it to flow better.

I hope to acquire an older diesel pickup next to do more testing on.

Hi guys,

I heard hasan koten achieved biogas + diesel dual fuel modeling in multidimensional framework in marmara university, turkey. i sent email and he optimized the fuel rates and injection parameters in 3D. you can ask him what kind of code and combustion model he used.