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Author Topic: NG / Propane dosing on Listeroids  (Read 12624 times)

sailawayrb

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Re: NG / Propane dosing on Listeroids
« Reply #15 on: July 03, 2014, 04:56:11 PM »
I don't have any experience with running with WVO, only SVO.  I don't have any experience with injecting straight water water either.  Running propane simply results in more complete combustion which results in less residual carbon formation.  Furthermore, a by-product of propane combustion is a significant amount of water vapor.  So in addition to getting more complete combustion with the associated increase in mechanical horsepower, one also continuously steam cleans the combustion chamber when running propane.  So I suppose one could say that one is BOTH minimizing the formation of carbon and also quickly removing any carbon that may result.  This really isn't new knowledge as propane combustion chemistry has been known and taught in mechanical engineering design courses for many years

buickanddeere

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Re: NG / Propane dosing on Listeroids
« Reply #16 on: July 03, 2014, 08:11:12 PM »
Water injection may increase power in a spark ignition engine that is ofherwise suffering detonation. The vapourizing water will lower the air-fuel mixture during the compression stroke.
   The higher the coolant temp the cleaner the combustion.
    Tractor pullers do on occasion hydro-lock engines .
     As for injection upstream of the turbo. Don't worry, those compressor impellers are eroding .
       All factors identical. The intake charge will be cooler injecting the water down stream of the turbo than upstream.

dieselgman

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Re: NG / Propane dosing on Listeroids
« Reply #17 on: July 04, 2014, 10:30:49 AM »
LPG is about 15% less than gasoline here in the Midwest now. Easy to purchase and handle in 20# to 50# bottles and we run some of our forklifts on this fuel. Many heating systems are run with this fuel in locations where the natural gas pipelines do not reach, delivery is by truck into large storage tanks. I remember that once, awhile back, propane was far cheaper than gasoline in Canada and I had a bus with large frame-mounted tank and conversion kit, I could switch over carbs and tweak timing a bit and save money when traveling back and forth from Alaska. Propane does not go 'stale' or otherwise degrade in storage like other petroleum fuels and our Natural Gas Listers - HRGs - will run fine on it (at 100%) with a slight timing adjustment.

As far as backup generators go, there are many systems marketed here by Generac and others that run on multi-fuel - both gasoline and propane. As far as system setup and installation goes, most municipalities have building codes that cover the details and professionals are generally recommended - sometimes required. I am not aware of issues with additional insurance where I operate.

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Thob

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Re: NG / Propane dosing on Listeroids
« Reply #18 on: July 06, 2014, 10:19:32 PM »

I wasn't aware of the gas making water vapor. I'll have to look that up as I'm wondering what takes place to make that happen.

...


When you burn any hydrocarbon fuel, the hydrogen combines with oxygen to produce H2O (water).  The carbon combines with oxygen to produce CO2.  The only difference between the fuels is how much hydrogen VS carbon it contains.  Methane (natural gas) is CH4, so 4 hydrogen atoms for 1 carbon.  Propane is C3H8, butane is C4H10, octane is C8H18, and so on.  Real fuels are never as pure as a single component, so it's a little more complicated than that but as the chain gets longer, the ratio approaches 2 hydrogen for 1 carbon.

Because the combustion is hot, the H2O will be steam.  I think to clean the deposited carbon out of an engine, you need liquid water to enter the combustion chamber, soak into the carbon, then flash to steam, exploding the carbon away from whatever it is deposited on.  I don't think water vapor entering the intake or steam produced during combustion does much to clean the carbon deposits.  That's just my theory, I don't have any hard evidence for it.

The other aspect of burning natural gas or LPG, is that it is already a gas.  In order to burn gasoline, it has to evaporate first to combine with air.  If liquid gas enters the cylinder, it may not evaporate in time to burn properly, thus leaving deposits behind.  In an environment lacking oxygen, the hydrogen will burn off leaving the carbon behind.  Any liquid fuel entering the cylinder has the opportunity to create a localized area that is fuel-rich (lacking oxygen) and thus not burn well.  A lot of the engineering in gasoline fuel injection and diesel injection is getting the fuel to completely mix with the air.  That is much simpler if you start with a fuel that is already a vapor.

 
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dieselgman

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Re: NG / Propane dosing on Listeroids
« Reply #19 on: July 07, 2014, 12:57:20 AM »
Quote
I think to clean the deposited carbon out of an engine, you need liquid water to enter the combustion chamber, soak into the carbon, then flash to steam, exploding the carbon away from whatever it is deposited on.  I don't think water vapor entering the intake or steam produced during combustion does much to clean the carbon deposits.  That's just my theory, I don't have any hard evidence for it.

However it happens, it does certainly work! Water injection will clean out at least some portion of combustion chamber deposits when done correctly. Of course, preferable to never build up the carbon in the first place! Propane dosing is a viable aid in this case.


CH4 vs C3H8
Just from the chemical numbers one might think that natural gas would burn cleaner than propane... I can tell you that the guts of a natural gas engine with similar run-time to a propane engine will show more combustion chamber deposits, but those deposits are often gray and white, not necessarily carbon. I am thinking that this might in part be an indication of the impurities in the fuel stocks.

dieselgman
« Last Edit: July 07, 2014, 12:59:20 AM by dieselgman »
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