I think there has to be more than meets the eye on such a conversion.
Propane is stored a liquid and I assume methane is as well. Can the propane
tanks withstand the pressure required to liquefy methane? Propane contains
more energy than methane, will you realize a net savings? In any event I
would guess you would have to adjust the fuel/air metering.
Doug
----- Original Message -----
From: <[EMAIL PROTECTED]>
To: <[EMAIL PROTECTED]>
Sent: Wednesday, March 09, 2005 10:33 AM
Subject: [Biofuel] Methane to LPG car
: I have an old petrol car (75 mercedes 230.4) converted to LPG recently.
: But In the last few months the price of LPG has started to rise. I am
: wondering if it is possible to use methane instead of LPG?
:
: I have a fridge compressor that I can compress the methane in to tanks,
: the could I just connect the tank instead of the LPG tank?
:
: Could somebody tell me if this is doable with ease or would I need to
: further convert the engine.
:
: Thanks
Until recently I worked fitting Autogas converisons to petrol vehicles.
Methane, or CNG (compressed natural gas) conversions are common. The
electronic mixture control kits I used to perform lpg conversions were
usually capable of running with CNG with most brands having dedicated
kits for this type of conversion (same electronics and fuel metering
just different pressure regulators.) Storage is usually by high pressure
tanks which are NOT THE SAME as lpg tanks. The pressures are very high
as oppose to the 7-10 bar inside a lpg tank. The gas could be stored at
something like 100bar and I dont think it liquified at this. It was
usual for lots of small cylinders to be fitted in an array in the back
of vans etc. refuelling was carried out via an expensive multi stage
compressor which was plugged into the filler adaptor each night and the
tank was refuelled over night. I was led to believe that compressors
were in the region of £5000UK. If the engine is fitted with a closed
loop mixture control system you would get away with little or no
adjustment to the software as long as the regulator output pressure was
matched. You could not use the standard lpg regulator as it would not
flow enough gas with a pre-regulator dropping the pressure down to a
level that it could take. This is because the lpg regulators are
designed to have a liquid feed and expansion into gas form takes place
inside it. The first stage of the lpg regulator simply wouldn't be able
to flow enough watts of gas vapour to feed the engine. You could
pressurise a lpg tank safely to about 10bar and the car would run, it
just wouldn't go very far and anything above even a fast idle would make
the mixture lean off. It would drive EXACTLY like your current lpg car
does when the tank runs dry and the engine is feeding on vapour pressure
from the tank.
Regards
Chris Bennett..
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