Pool spreading and vaporization of liquid hydrogen

Abstract

An essential part of a safety analysis to evaluate the risks of a liquid hydrogen (LH 2 ) containing system is the understanding of cryogenic pool spreading and its vaporization. It represents the initial step in an accident sequence with the inadvertent spillage of LH 2 , e.g., after failure of a transport container tank or the rupture of a pipeline. This stage of an accident scenario provides pertinent information as a source term for the subsequent analysis steps of atmospheric dispersion and, at presence of an ignition source, the combustion of the hydrogen-air vapor cloud. A computer model LAUV has been developed at the Research Center Juelich, which is able to simulate the spreading and vaporization of a cryogenic liquid under various conditions such as different grounds (solid, water). It is based on the so-called shallow-layer differential equations takingg into account physical phenomena such as ice formation, if the cryogen is spilled on a water surface. This paper gives a description of the computer model and its validation against existing experimental data. Furthermore, computational results are analyzed describing the prediction and quantification of the consequences of an LH 2 spill for different cases. They also include the comparison of an LH 2 spillage versus the corresponding release of other cryogens such as liquefied natural gas, liquid oxygen, and liquid nitrogen. ᭧

Safety challenges in view of the upcoming hydrogen economy: An overview

“…NASA has conducted several trials to investigate the hazards of LH 2 in large rockets to propel spacecraft. More recently in Germany by BAM, cryogenic spreading pool experiments have been performed, while Research Center Juelich developed the LAUV pool spreading and evaporation model validated against experimental results with LH 2 , liquefied natural gas (LNG), and nitrogen as reported by Verfondern and Dienhart (2005). An application was in a project to investigate the effects of a crash of an Airbus A310 fueled on LH 2 .…”

“…Evaporation will also be less forceful after the top of the soil has been cooled down, which occurs when the layer is thicker. Tests have been conducted and described by Verfondern and Dienhart (2005), and the results have been used to validate a model. The model predicts, for a 240 m 3 unbunded pool at instantaneous (point) release, an evaporation time of 25 s, much shorter than for LNG.…”

CFD modeling and analysis of the influence factors of liquid hydrogen spills in open environment

“…Despite many influencing factors have been considered in the model, there still exists much difference between the simulation settings and the experimental setup. For instance, the ground was reported to be compacted dry sand, however, the furrows observed after the tests in the sand indicate that a certain fraction of the LH 2 penetrated the sand, thus, enhanced the vaporization rate due to the enlarged surface area and reduced the amount of LH 2 left to spread on the ground [31]. Another reason for the relatively higher initial dispersion rates is the splashing of LH 2 by a steel plate located underneath the LH 2 source.…”

High-order perturbation solutions to a LH2 spreading model with continuous spill

“…The evaporation rate per unit area of LH 2 on a paraffin wax ground [4] varies from about 4.23 Â 10 À4 m/s to about 12.7 Â 10 À4 m/s. Therefore, the dimensionless evaporation rate, 3, can be chosen as the perturbation parameter.…”