(57af) Hazards of LNG Releases - an Efficient Numerical Modeling Technique

Abstract

In previous work [1], a two-phase Smoothed
Particle Hydrodynamics (SPH) model was developed for the simulation of the
release and spreading of LNG over complex terrain. Compared to traditional
multiphase CFD methods, the meshless SPH approach has several advantages, such
as (i) excellent mass conservation, especially when
modeling small-scale features of moving and deforming fluid interfaces (e.g.
thin films or small vapor bubbles); (ii) efficient tracking of complex
interface deformation and movement; and (iii) effective dealing with complex
flow boundaries. As a result, the SPH method is found to be suitable for
simulating LNG loss of containment events where the details of the release and
spreading events.

In this work, the SPH model is further
developed to include a more advanced treatment of the near-boundary
vaporization. With conjugate heat transfer between the LNG and the solid
substrate taken into consideration, the heat flux going into LNG heating and
phase change is determined based on the assumption of film boiling heat
transfer domination. The near-boundary vaporization model is tested in
simulations of boiling with single bubble growth on horizontal and vertical
heating surfaces.
The dispersion and the possible combustion
of vaporized LNG are important issues in the LNG release hazard analysis. The
mixing and transport of LNG vapor with air, however, are better described by
traditional multiphase CFD models. The above-mentioned SPH model of LNG spreading
is proposed to be coupled with the CFD solver OpenFOAM using LIGGGHTS CFD-Coupling
[2]. A limited testing of the coupled SPH-OpenFOAM model for a realistic large
scale LNG release scenario is conducted and discussed.
Reference:
[1] Bui, A., Reed, M., Liu, T., and
Peterson, E., “Modelling of LNG Spreading and Vaporization Using Smoothed
Particle Hydrodynamics Method”, Proceedings of the 12^th AIChE GCPS,
Houston, Texas, April, 2016.
[2] www.cfdem.com