| dc.description.abstract | Due to an increasing importance of liquid hydrogen (LH2) in energy sector and since much of LH2 transport is conducted by sea, investigation of potential accidents from LH2 spills onto and under water is of particular interest. The present work focuses on hazards related to cryogenic hydrogen release under water in large scale.
In case of accidental release of cryogenic hydrogen under water, elevated heat transfer causes rapid LH2 evaporation. The rate of LH2 evaporation depends on the temperature difference between LH2 and water. Rapid LH2 evaporation has the potential to lead to explosive boiling and cause rapid phase transition (RPT), and consequently producing significant overpressures.
The aim of the thesis is to model the consequences generated during accidental releases of liquid hydrogen under water by means of numerical modelling. The possibility and consequences of early LH2 RPT are studied through detailed multiphase simulations of the LH2-water in mixing region under water.
A two-dimensional (2D) axisymmetric model is developed using commercial computational fluid dynamics (CFD) software ANSYS FLUENT that can simulate the behavior of LH2 injection into water from their initial release, mixing into the water, and estimation of potential early RPT. The thermodynamic properties of cryogenic hydrogen are extracted from the national institute of standards and technology (NIST) webbook in which data are originated based on quantum mechanics. A volume of fluid (VOF) based Eulerian method with surface tension effects is used to compute a time-dependent solution for mixing zone of LH2 and water. Reynolds Averaged Navier Stokes (RANS) turbulence models of standard k-ε and shear-stress transport (SST) k-ω are applied and the results are compared.
The experimental outcomes of the Safe Hydrogen Fuel Handling and Use for Efficient Implementation (SH2IFT) project are exploited to validate the developed models. Simulation results were compared with experimental analysis and showed good consistency. | |