This study deals with the TNO Multi-Energy and Baker-Strehlow-Tang (BST) methods for estimating the positive overpressures and positive impulses resulting from hydrogen-air explosions. With these two methods, positive overpressure and positive impulse results depend greatly on the choice of the class number for the TNO Multi-Energy method or the Mach number for the BST methods. These two factors permit the user to read the reduced parameters of the blast wave from the appropriate monographs for each of these methods, i.e., positive overpressure and positive duration phase for the TNO Multi-Energy method, and positive overpressure and positive impulse for the BST methods. However, for the TNO Multi-Energy method, the determination of the class number is not objective because it is the user who makes the final decision in choosing the class number, whereas, with the BST methods, the user is strongly guided in their choice of an appropriate Mach number. These differences in the choice of these factors can lead to very different results in terms of positive overpressure and positive impulse. Therefore, the objective of this work was to compare the positive overpressures and positive impulses predicted with the TNO Multi-Energy and BST methods with data available from large-scale experiments.

This study addresses one of knowledge gapsin hydrogen safety science and engineering, i.e. apredictive model for calculation of deterministic separation distancesdefined bythe parameters ofa blast wave generated by a high-pressure gasstorage tank rupture in a fire. An overview of existing methods to calculate stored in a tank internal(mechanical) energy anda blast wave decayis presented. Predictions by the existing techniqueand anoriginal modeldeveloped in this study, whichaccountsforthe real gas effects and combustion of the flammable gasreleasedintotheair(chemical energy),arecompared againstexperimental dataon high-pressurehydrogen tank rupture in thebonfiretest. The main reasonfor a poor predictive capability of the existing models isthe absenceof combustion contribution to the blast wave strength. The developed methodologyis able to reproduce experimental data on a blast wave decay after rupture of a stand-alone hydrogen tank and atank under avehicle.In this study, the chemical energy isdynamically added to the mechanical energy and is accounted for in the energy-scaled non-dimensional distance. The fractionof the total chemical energy of combustion released to feed the blast wave is 5%2and9%2 howeverit is 1.4 and 30 times larger than the mechanical energy in the stand-alone tank test and the under-vehicle tank test respectively.The model isappliedas a safetyengineering tool to fourtypical hydrogen storage applications,includingon-board vehicle storage tanksand a stand-alone refuelling station storage tank. Harm criteria topeople and damage criteria for buildings froma blast wave are selected by the authorsfrom literature to demonstratethe calculation of deterministicseparation distances.Safety strategiesshouldexclude effectsoffire on stationary storage vessels, and requirethermal protection of on-board storage to prevent dangerous consequences ofhigh-pressure tank rupture in a fire.