Methane Number Calculation
Methane Number Calculation
(OP)
Hi everybody,
I preiouly posted this question in another forum. Can anybody help?
I am trying to figure out how to calculate the Methane Number (MN) for a given gas composition. I tried to find some information in the literature but was not successful.
I only found the following formulas:
MON = -406.14 + 508.04*(H/C) – 173.55*(H/C)^2 + 20.17*(H/C)^3
MN = 1.624*MON – 119.1
with H/C being the hydrogen/carbon ration. (MON = motor octane number).
Having tried it on several gas compositions, I am always off by some 10% of the real MN number. Even if I take 100% CH4,I get a MN=108 which is obviously wrong.
Would it be possible to calculate the MN of the gas composition based on the MN of the various constituents multiplied by the Mol %, such as done to calculate the Molecular Weight of the gas? If yes, where can I find the MN numbers for the various elements?
Thanks in advance.
I preiouly posted this question in another forum. Can anybody help?
I am trying to figure out how to calculate the Methane Number (MN) for a given gas composition. I tried to find some information in the literature but was not successful.
I only found the following formulas:
MON = -406.14 + 508.04*(H/C) – 173.55*(H/C)^2 + 20.17*(H/C)^3
MN = 1.624*MON – 119.1
with H/C being the hydrogen/carbon ration. (MON = motor octane number).
Having tried it on several gas compositions, I am always off by some 10% of the real MN number. Even if I take 100% CH4,I get a MN=108 which is obviously wrong.
Would it be possible to calculate the MN of the gas composition based on the MN of the various constituents multiplied by the Mol %, such as done to calculate the Molecular Weight of the gas? If yes, where can I find the MN numbers for the various elements?
Thanks in advance.





RE: Methane Number Calculation
A qick search led me to the same equations you specified for MON and MN (probably we visited the same internet site: www.arb.ca.gov/regact/cng-lpg/appe.doc)
But there are more sites talking about MN, for example: uk.dgc.dk/publications/algotitme.htm - 4k , http://speonline.spe.org/events/urls/2002gts/SPE75509.pdf , etc.
Since you posted your question almost two months ago maybe there is no need for this reply?!?
RE: Methane Number Calculation