Multiphase Flow Modeling of LNG Using Smoothed Particle Hydrodynamic (SPH) Techniques

Abstract

Smoothed Particle Hydrodynamics (SPH) has shown promise when used for numerical simulation of the release of LNG and the subsequent spreading of the liquid. Although the SPH method has been used for years in the astrophysics industry, its application to the LNG industry is quite novel.  The spreading and vaporization of LNG creates the potential for a large vapor cloud with the risk of an explosion or flash fire. Vaporization of LNG during its spreading over water or solid substrate involves either evaporation at the air - LNG interface or nucleate/film boiling upon contact of cold LNG with relatively high-temperature substrate surface. For the later vaporization mechanism to be correctly modeled, surface temperature and its subsequent change due to contact with LNG needs to be described. Consequently, a conjugate heat transfer model which includes wall heat conduction would be necessary. The SPH method offers excellent mass conservation, especially when modeling small scale changing fluid interfaces (i.e. thin film or small vapor bubbles).

This paper discusses the continued development of a multiphase flow model with heat transfer and phase change based on the SPH model available in the LAMMPS Molecular Dynamics Simulator software. A mechanistic film boiling model is implemented and incorporated into our SPH flow model.  The conjugate heat transfer between the moving LNG layer and surrounding environment (substrate) is also modeled to account for the cooling of the substrate over time.  Limited validation of the SPH prediction of the LNG spreading will be conducted and examples showing the enhanced boiling and heat transfer capabilities of the proposed LNG spreading model will be outlined and discussed.