The iso6976 performs the calculation of the natural gas properties in accordance with:
ISO-6976/1995, TC-2/1997 and TC-3/1999: Natural gas - Calculation of calorific values, density and Wobbe index from composition.
Table 1: Description of the iso6976 class interface: properties (variables), methods (functions) and error flags.
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PROPERTIES |
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Natural gas component |
Set property value |
Get property value |
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I |
X(I) mole fraction for |
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0 |
Methane |
void SetFractionValue(short I, double X(I)) |
double GetFractionValue (short I) |
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1 |
Ethane |
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2 |
Propane |
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3 |
n-Butane |
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4 |
2-Methylpropane |
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5 |
n-Pentane |
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6 |
2-Methylbutane |
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7 |
2,2-Dimethylpropane |
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8 |
n-Hexane |
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9 |
2-Methylpentane |
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10 |
3-Methylpentane |
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11 |
2,2-Dymethylbutane |
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12 |
2,3-Dymethylbutane |
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13 |
n-Heptane |
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14 |
n-Octane |
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15 |
n-Nonane |
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16 |
n-Decane |
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17 |
Ethylene |
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18 |
Propylene |
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19 |
1-Butene |
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20 |
cis-2-Butene |
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21 |
trans-2-Butene |
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22 |
2-Methylpropene |
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23 |
1-Pentene |
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24 |
Propadiene |
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25 |
1,2-Butadiene |
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26 |
1,3-Butadiene |
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27 |
Acetylene |
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28 |
Cyclopentane |
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29 |
Methylcyclopentane |
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30 |
Ethylcyclopentane |
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31 |
Cyclohexane |
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32 |
Methylcyclohexane |
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33 |
Ethylcyclohexane |
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34 |
Benzene |
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35 |
Toulene |
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36 |
Ethylbenzene |
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37 |
0-Xylene |
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38 |
Methanol |
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39 |
Methanethiol |
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40 |
Hydrogen |
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41 |
Water |
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42 |
Hydrogen sulfide |
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43 |
Ammonia |
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44 |
Hydrogen cyanide |
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45 |
Carbon monoxide |
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46 |
Carbonyl sulfide |
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47 |
Carbon disulfide |
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48 |
Helium |
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49 |
Neon |
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50 |
Argon |
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51 |
Nitrogen |
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52 |
Oxygen |
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53 |
Carbon dioxide |
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54 |
Sulfur dioxide |
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55 |
Dinitrogen monoxide |
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56 |
Krypton |
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57 |
Xenon |
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Mixture analysis |
Set property value |
Get property value |
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N |
Description |
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0 |
Molar fractions |
void SetMixtureAnalysis(short N) |
short GetMixtureAnalysis () |
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1 |
Volume fractions |
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2 |
Mass fractions |
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Combustion/metering operating conditions |
Set property value |
Get property value |
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N |
Description |
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0 |
15°C/15°C and 101.325 kPa |
void SetCombustionMeteringConditionsC(short N) |
short GetSetCombustionMeteringConditions () |
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1 |
0°C/0°C and 101.325 kPa |
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2 |
15°C/0°C and 101.325 kPa |
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3 |
25°C/0°C and 101.325 kPa |
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4 |
20°C/20°C and 101.325 kPa |
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5 |
25°C/20°C and 101.325 kPa |
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Error status |
- |
long int GetErrorFlag() |
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RESULTS |
Set property value |
Get property value |
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I |
Description |
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0 |
Superior calorific value - molar basis [kJ/mol] |
- |
double GetResults (short I) |
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1 |
Inferior calorific value - molar basis [kJ/mol] |
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2 |
Superior calorific value - mass basis [MJ/kg] |
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3 |
Inferior calorific value - mass basis [MJ/kg] |
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4 |
Superior calorific value - volumetric basis [MJ/m3] |
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5 |
Inferior calorific value - volumetric basis [MJ/m3] |
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6 |
Molar mass [kg/mol] |
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7 |
Compression factor |
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8 |
Relative density |
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9 |
Density [kg/m3] |
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10 |
Molar density [kg-mole/m3] |
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11 |
Wobbe index [MJ/m3] |
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METHODS |
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Calculation of natural gas properties in accordance with ISO-6976 |
long int CalculateIso6976(); calculates natural gas properties and returns long int error status |
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ERROR STATUS |
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Error status bits are cleared or set upon the completion of long int CalculateIso6976() function as shown below |
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Bit 0 =1 (0001H) |
The total sum of mole fractions is <0.98 or >1.02. |
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Bit 1 =1 (0002H) |
The total sum of mole fractions is not exactly equal to 1. This bit denotes only the warning that the fractions have been normalized to give the total sum of mole fractions equal to 1. If only bit 2 was set during the calculation the results are valid. |
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Bit 2 =1 (0004H) |
The mole fraction of Methane is <0.5 or >1.0. |
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Bit 3 =1 (0008H) |
The mole fraction of Nitrogen is <0 or > 0.3. |
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Bit 4 =1 (0010H) |
The mole fraction of Carbon Dioxide is <0 or >0.15. |
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Bit 5 =1 (0020H) |
The mole fraction of Ethane is <0 or >0.15. |
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Bit 6 =1 (0040H) |
The mole fraction of any other mixture component {X(2),...,X(50),X(52),X(54),...,X(57)} is <0 or >0.05 |
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Bit 7,... |
Bit 7 and all higher bits are unused. |
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