Influences of Hydrogen Blending on the Joule–Thomson Coefficient of Natural Gas

[Image: see text] Blending hydrogen into the natural gas pipeline is considered as a feasible way for large-scale and long-distance delivery of hydrogen. However, the blended hydrogen can exert major impacts on the Joule–Thomson (J–T) coefficient of natural gas, which is a significant parameter for liquefaction of natural gas and formation of natural gas hydrate in engineering. In this study, the J–T coefficient of natural gas at different hydrogen blending ratios is numerically investigated. First, the theoretical formulas for calculating the J–T coefficient of the natural gas–hydrogen mixture using the Soave–Redlich–Kwong (SRK) equation of state (EOS), Peng–Robinson EOS (PR-EOS), and Benedict–Webb–Rubin–Starling EOS (BWRS-EOS) are, respectively, derived, and the calculation accuracy is verified by experimental data. Then, the J–T coefficients of natural gas at six different hydrogen blending ratios and thermodynamic conditions are calculated and analyzed using the derived theoretical formulas and a widely used empirical formula. Results indicate that the J–T coefficient of the natural gas–hydrogen mixture decreases approximately linearly with the increase of the hydrogen blending ratio. When the hydrogen blending ratio reaches 30% (mole fraction), the J–T coefficient of the natural gas–hydrogen mixture decreases by 40–50% compared with that of natural gas. This work also provides a J–T coefficient database of a methane–hydrogen mixture with a hydrogen blending ratio of 5–30% at a pressure of 0.5–20 MPa and temperatures of 275, 300, and 350 K as a reference and a benchmark for interested readers.