Mass-based gross calorific value (HHV) of an LNG cargo from gas-chromatograph composition per ISO 6976:2016 - the reference method for invoice energy on LNG bills of lading.
Formula
$$ \text{GCV}_m = \sum x_i \cdot \text{GCV}_i^{mol}, \quad \text{GCV}_{kg} = \frac{1000 \cdot \text{GCV}_m}{\sum x_i M_i} $$Symbol legend
| Symbol | Meaning | Unit | Source |
|---|---|---|---|
| $x_i$ | Mole fraction of component | mol/mol | GC analysis |
| $\text{GCV}_i^{mol}$ | Molar GCV of pure component | kJ/mol | ISO 6976 Annex A |
| $M_i$ | Molar mass of component | g/mol | IUPAC |
Sources
- ISO 6976:2016.
- GIIGNL Custody Transfer Handbook.