I have now logged over 750 miles using supplemental cng. I am not getting as good of diesel mileage as I do with lp. I need to modify the regulator to enable more flow. I will be changing the first stage regulator spring tomorrow to bring the pressure up. I'll also verify that I have at least 100 psi from the high pressure regulator. It runs really nice, I just want to use more gas and less diesel. The small tank is a pain. Only carrying 10 gal gasoline equivalent is nothing like my 100 gal lp tank. I'm used to serious range. I filled up with cng at one place, they didn't even charge me for the fuel.
Marc;
You state that you get lower emissions, what verifiable tests have you done? It appears that all the adjustments you have performed are by the seat of the pants. This is fine for establishing a baseline, but in order to provide repeatable results, you need to perform verifiable testing with a third party.
Tossing in a hydrocarbon fuel on top of a hydrocarbon fuel produces hydrocarbon emissions. Add in the fact that one of the fuels is a combustion ignition fuel with excess air and we have a NOx producer.
Please understand that I am in no way against a dual fuel application, but lets see the results on one that produces repeatable results.
Franz
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Franz,
You are right, I haven't actually done any emission testing. I am basing some of my statements on what I have observed, and some on what results others have seen. The engine only runs about half the boost while adding a gaseous fuel that it runs while on #2. I theorize that this is because more (or all) of the available O2 is being consumed rather than just what is needed to burn the #2. This means that much less air is being pumped through the engine for the same power output. One look at the oil will tell you that the combustion has to be cleaner than the average diesel. I use a bypass filter and have never changed the oil, I get it analyzed periodically. It now has 48K on it and the last analysis showed only a trace of soot. I have run lp, lots of it, since the truck had 400 miles on it. I have used at least 1 gal of lp to 1 gal of #2 since the beginning, and for the last 20K miles it has been at least 2 gal lp to 1 gal #2. I look forward to some more miles with the cng, but don't plan to use it long term. Today I raised the output of the high pressure regulator from 150 to 200 psi, and the first stage of the low pressure reg from 1.5 to 3 psi. We'll see what the next roadtrip gives me for mileage. I wish I had better ways to quantify things, but I have to work with what I've got.
So do I. All I have to do is recover it, make it in usable form, store it somewhere, find some way to distribute it, license and certify it, ensure that it works all the time, and protect it.
Yep, doesnt cost me a penny.
You wouldnt be any way connected to the Biomass experts?
Franz
eng-tips, by professional engineers for professional engineers
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.
easy solution, 30% diesel 70% gas.
almost no rebuild needed for fuel system. a easy injection system just before inatke and piggy back the system can make the diesel very cheap.
and no spark plugs needed.
