1、Designation: D8221 18Standard Practice forDetermining the Calculated Methane Number (MNC)ofGaseous Fuels Used in Internal Combustion Engines1This standard is issued under the fixed designation D8221; the number immediately following the designation indicates the year oforiginal adoption or, in the c
2、ase of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This practice covers the method to determine the calcu-lated methane number (MNC) of a ga
3、seous fuel used in internalcombustion engines. The basis for the method is a dynamiclink library (DLL) suitable for running on computers withMicrosoft Windows operating systems.1.2 This practice pertains to commercially available naturalgas products that have been processed and are suitable for usei
4、n internal combustion engines. These fuels can be fromtraditional geological or renewable sources and include pipe-line gas, compressed natural gas (CNG), liquefied natural gas(LNG), liquefied petroleum gas (LPG), and renewable naturalgas (RNG) as defined in Section 3.1.3 The calculation method with
5、in this practice is based onthe MWM Method as defined in EN 16726, Annex A.2Thecalculation method is an optimization algorithm that usesvarying sequences of ternary and binary gas component tablesgenerated from the composition of a gaseous fuel sample.3Both the source code and a Microsoft Excel-base
6、d calculatorare available for this method.1.4 This calculation method applies to gaseous fuels com-prising of hydrocarbons from methane to hexane and greater(C6+); carbon monoxide; hydrogen; hydrogen sulfide; nitro-gen; and carbon dioxide. The calculation method addressespentanes (C5) and higher hyd
7、rocarbons and limits the indi-vidual volume fraction of C5 and C6+ to 3 % each and acombined total of 5 %. (See EN 16726, Annex A.) Thecalculation method is performed on a dry, oxygen-free basis.1.5 UnitsThe values stated in SI units are to be regardedas standard. Other units of measurement included
8、 in thisstandard practice are for reference only.1.6 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety, health, and environmental practices and deter-mine the app
9、licability of regulatory limitations prior to use.1.7 This international standard was developed in accor-dance with internationally recognized principles on standard-ization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recom-mendations issued by
10、 the World Trade Organization TechnicalBarriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:4E29 Practice for Using Significant Digits in Test Data toDetermine Conformance with Specifications2.2 CEN Standard:5EN 16726 Gas infrastructureQuality of gasGroup H,Annex ACalculation
11、of methane number of gaseousfuels for engines2.3 ISO Standard:6ISO 14912 Gas analysisConversion of gas mixture com-position data2.4 ASTM Adjuncts:ASTM_D8221_mzdll_ver2.32.0.dll7ASTM_D8221_MNc_Method_ver1.32.0.xlsb73. Terminology3.1 Definitions:1This practice is under the jurisdiction of ASTM Committ
12、ee D03 on GaseousFuels and is the direct responsibility of Subcommittee D03.03 on Determination ofHeating Value and Relative Density of Gaseous Fuels.Current edition approved Sept. 1, 2018. Published October 2018. DOI: 10.1520/D8221-18.2European Standards (ENs) are documents that have been ratified
13、by one of thethree European Standardization Organizations (ESOs), CEN, CENELEC or ETSI;recognized as competent in the area of voluntary technical standardization as for theEU Regulation 1025/2012. EN16726 was developed by the Technical CommitteeCEN/TC 234.3Leiker, M., Christoph, K., Rankl, M., Carte
14、llieri, W., Pfeifer, U., “Evaluation ofAntiknocking Property of Gaseous Fuels by Means of Methane Number and itsPractical Application to Gas Engines,” ASME, 72-DGP-4, 1972.4For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For An
15、nual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.5Available from European Committee for Standardization (CEN), AvenueMarnix 17, B-1000, Brussels, Belgium, http:/www.cen.eu.6Available from American National Standards Institute (ANSI), 25 W
16、. 43rd St.,4th Floor, New York, NY 10036, http:/www.ansi.org.7Available from ASTM International Headquarters. Order Adjunct No.ADJD822118-EA. Original adjunct produced in 2018.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United StatesThis intern
17、ational standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Comm
18、ittee.13.1.1 compressed natural gas (CNG), nnatural gas thathas been compressed after processing for storage or transpor-tation purposes.3.1.1.1 DiscussionCNG is primarily used as a fuel forvehicles, typically compressed up to 24 821 kPa in the gaseousstate.3.1.2 liquefied natural gas (LNG), nnatura
19、l gas that hasbeen liquefied after processing for storage or transportationpurposes.3.1.2.1 DiscussionLiquefied natural gas is revaporizedand introduced into pipelines for transmission and distributionas natural gas and may be used as a fuel for internalcombustion engines.3.1.3 liquefied petroleum g
20、as (LPG), na gaseous fuel thathas been liquefied after processing for storage or transportationpurposes composed primarily of propane, propene (propylene),butane, and mixtures of these gases.3.1.3.1 DiscussionThis special mixture of gases was spe-cifically developed for use as a fuel in spark ignite
21、d internalcombustion engines. Limits are applied to propene and butane,which are used to adjust the vaporization pressure. When usedin vehicles, LPG is specified as HD-5 propane or HD-10propane.3.1.4 methane number (MN), nan experimental determi-nation of a gaseous fuels resistance to knock based on
22、 aCooperative Fuel Research (CFR) Motor Octane Number(MON) test engine and indicated by the volume of methane ina blend with hydrogen.3.1.4.1 DiscussionMethane has a value of MN=100 andhydrogen has a value of MN=0.3.1.5 methane number, calculated (MNC), na calculationof a rating index, indicating th
23、e resistance to knock of agaseous fuel when compared to a reference methane/hydrogenmixture.3.1.5.1 DiscussionMultiple methods have been developedin the past for providing this analytical estimate based on gascomposition. A MNCis determined using volumetric fuelcomposition. Sometimes MNCis described
24、 as “methane index(MI).”3.1.6 natural gas, na naturally occurring mixture of hy-drocarbon and nonhydrocarbon gases found in porous geologi-cal formations (reservoirs) beneath the earths surface, often inassociation with petroleum. The principal component of natu-ral gas is methane.3.1.7 pipeline gas
25、, ngas that is refined to high qualitylevels and transported in natural gas pipeline systems.3.1.8 renewable natural gas (RNG), na pipeline-qualitygas that is all or in part from renewable sources, and is fullyinterchangeable with geological natural gas.3.1.8.1 DiscussionRNG can be biogas or biometh
26、ane (thegaseous product of the decomposition of organic matter) thathas been processed to purity standards and thus can be used asa fuel for internal combustion engines.3.1.8.2 DiscussionLike geological natural gas, RNG canbe used for transportation purposes in the form of compressednatural gas (CNG
27、) or liquefied natural gas (LNG).3.2 Definitions of Terms Specific to This Standard:3.2.1 commercially available, adja natural gas productfrom more than one non-governmental entity that may bedistributed to more than one user.3.2.1.1 DiscussionExamples of commercially availablenatural gas products a
28、re pipeline gas from a utility, CNG froma fueling station, and so forth.3.2.1.2 DiscussionExamples of natural gas that is notcommercially available include well-head gas, landfill gas,methane digester gas, and so forth.4. Summary of Calculation Method4.1 The application of analytical methods to grou
29、ps ofternary and binary mixtures of gas components with knownmethane numbers that reflect the makeup of the gaseous fuelmixture is the basis for this calculated methane numbermethod.4.2 This calculation method originates with the data of aresearch program performed by AVL Deutschland GmbH forFVV and
30、 was updated and revised by MWM GmbH and thenfinally published for global use in EN16726, Annex A.5. Significance and Use5.1 The methane number (MN) is a measure of the resis-tance of the gaseous fuel to autoignition (knock) when used inan internal combustion engine. The relative merits of gaseousfu
31、els from different sources and having different compositionscan be compared readily on the basis of their methanenumbers. Therefore, the calculated methane number (MNC)isused as a parameter for determining the suitability of a gaseousfuel for internal combustion engines in both mobile andstationary
32、applications.CALCULATION METHOD6. Scope6.1 This calculation method applies to gaseous fuels asdefined by the Scope, and defined in Section 3, and listed inProcedure 8.1, Table 2.7. Significance and Use7.1 The methane number of a gaseous fuel can be calculatedbased on its composition by various analy
33、tical methods whichcan give different results. The results of the method describedin this practice match measured methane numbers (see X1.1and X2.1) with reasonable certainty for the fuels as defined inthis practice.TABLE 1 Error MessagesError Message Comment“The input sample total must be from 99%
34、to 101 %, inclusive; please correct!”No MNCvalue displayed“The MNc calculation is not possible dueto internal program errors!”No MNCvalue displayed“A valid MNc value cannot be calculated!” No MNCvalue displayed“A MNc value with reasonable certainty isnot possible due to high C5+ content!”No MNCvalue
35、 displayedD8221 1827.2 The method requires input of composition in the form ofvolume fractions at reference conditions of 15.55 C and101.325 kPa and expressed as a percentage. Compositionsavailable as either mole fraction or mass fraction are to beconverted to volume fraction using the methods cited
36、 in ISO14912. For general use, it may be assumed that mole fractionand volume fraction are equivalent.7.3 The final result, the calculated methane number, isexpressed as an integer per Practice E29.7.4 While this calculation method will provide results forgaseous fuel compositions outside the scope
37、of this practice,the results may have a higher degree of uncertainty.7.5 ErrorsThis calculation method may not apply tocertain gas compositions based on the component inputsviolating input limit requirements or due to the methodsinternal calculations and regressions being unable to develop acalculat
38、ed methane number value. Error messages are providedto the user and are listed in Table 1 and described in 7.5.1 to7.5.4.7.5.1 “The input sample total must be from 99 % to 101 %,inclusive; please correct!”The calculated methane numberprogram requires a gas sample composition that totals 99 % to101 %
39、, inclusive. Please correct the gas component inputsmanually or normalize the gas sample composition.7.5.2 “The MNCcalculation is not possible due to internalprogram errors!”A calculated methane number is not pos-sible for the given gas sample because the internal programiteration routines failed. D
40、uring the programs internal optimi-zation processes, the differences between calculated methanenumbers for various ternary mixtures used within the programwere outside allowable internal program limits and a reason-able MNCvalue could not be generated. An example of a gassample causing this error wo
41、uld be a high CH4compositionwith the rest of the sample containing H2and CO components(for example, 98 % CH4,1.8%H2and 0.2 % CO).7.5.3 “A valid MNCvalue cannot be calculated!”A cal-culated methane number is not possible for the given gassample because internal program data is not available tosupport
42、 the calculation method or the internal program pro-cesses were unable to complete the calculation. An example ofa gas sample causing this error would be a N2free compositionwith low CH4content and high CO2content (for example, 39%CH4and 61 % CO2).7.5.4 “A MNCvalue with reasonable certainty is not p
43、os-sible due to high C5+ content!”The calculation methodlimits the volume fraction of C5 and C6+ to 3 % each and atotal of 5 % for a given gas sample and will not provide acalculated methane number if these limits are exceeded due tothe high uncertainty in the result (for example, 94 % CH4,3%C5H12an
44、d3%C6H14).7.6 The basis for this method is a dynamic link library(DLL)8suitable for running on computers with 32-bit or 64-bitMicrosoft Windows operating systems.7.7 An Excel Virtual Basic forApplications (VBA) macro isavailable for a user to tailor their calculations for a specificapplication (see
45、A1.1). The DLL file is currently supported byonly an Excel 32-bit platform and not an Excel 64-bit platform.An Excel program using the VBA macro (see A1.1) has beendeveloped allowing for either individual or multiple gassamples (see A1.2). It also provides conversions for mass ormole fractions to vo
46、lume fraction per ISO 14912 as well as anormalization routine. A graphical user interface (GUI) couldalso be developed by a user to use the dynamic link libraryfile.98. Procedure8.1 Determine the volume composition of the gaseous fuelin accordance with any ASTM or GPA method (see X2.2.1 andX2.2.2) t
47、hat yields the complete composition in componentamounts of 0.1 % or more, in terms of the components listed inTable 2. Not all components listed in Table 2 must be input foraMNCvalue to be calculated. Several of the components arenot typically included in a standard gas chromatograph analysisof natu
48、ral gas, for example, oxygen, water, hydrogen sulfide,carbon monoxide, and hydrogen. However, these componentscan be quantified by other techniques if their concentrations areconsidered significant.8.2 Conversion from a mass-based composition or a molar-based composition and/or at different pressure
49、 or temperatureconditions should be done in accordance with ISO 14912. Allsignificant inputs should be in the form of volume fractionsexpressed as percentages at reference conditions of101.325 kPa, 15.55 C except H2S, which is in ppmv. Allmeasured hexane and higher hydrocarbons are combined andinput as hexane in the calculation regardless if their individualcomponent amounts are less than 0.1 %. If the measurementreported a value for hexane-plus hydrocarbons, then that valueshould be input as hexane. If the measurement reported a valuefor heptane-pl
