fundamentals of hydrogen safety engineering\_PPT\_Training.pdf

Slide Number 1 Contents Acknowledgements Hydrogen Safety Engineering: framework and subsystems Definition Terms and definitions (1/2) Terms and definitions (2/2) The scope The process Three main stages Sub-systems QDR: steps QDR: safety objectives QDR: acceptance criteria1 QDR: acceptance criteria2 QDR: fire scenarios Quantitative analysis of design Assessment against criteria1 Assessment against criteria2 Concluding remark (section 1) Non-reacting hydrogen jets Sunavala, Hulse, Thring, 1957 Ricou and Spalding, 1961 Chen and Rodi, 1980 Shevyakov et al., 1980 (1/2) Shevyakov et al., 1980 (2/2) Underexpanded jets Birch et al., 1984-1987 Birch vs Chen and Rodi Underexpanded jet theory Experimental data The similarity law data Mass vs volume fraction Buoyancy vs momentum Hydrogen jet fires Hawthorne et al., 1949 (1/2) Hawthorne et al., 1949 (2/2) Flame length data LF/D (Fr) Flame length data (Re) Kalghatgi, 1984 Similitude analysis New similarity group (mD) Novel universal correlation The nomogram for hydrogen safety engineering Special feature of the nomogram: Mogi et al., 2005: No stable flames were observed for nozzle diameters 0.1 and 0.2 mm – flame blew off although the spouting pressure increased up to 400 bar. Cross-analysis (non-reacting jets and jet fires) Where is the flame tip (1/2)? Where is the flame tip (2/2)? Concluding remarks (sections 2, 3) Venting of deflagrations Two peaks structure Four peaks structure Venting generated turbulence (1/3) Venting generated turbulence (2/3) Venting generated turbulence (3/3) Vent sizing technology (VST) Innovative VST vs NFPA 68 (EN 14994) Vent cover inertia Le Chatelier-Broun principle Hydrogen safety engineering and CFD Permeation Problem formulation (1/2) Problem formulation (2/2) Modelling (1/3) Modelling (2/3) Modelling (3/3) Allowable permeation rate Blowdown of high pressure hydrogen storage Steady and unsteady leaks Blowdown modelling Unsteady blowdown Spontaneous ignition of high pressure releases Experimental data Mechanism of ignition Transition to sustained fire Vortex induced “flame separation” LES of premixed combustion (multi-phenomena combustion model) Types of models Turbulent burning velocity models Flow turbulence Turbulence generated by flame front itself (1/2) Turbulence generated by flame front itself (2/2) Preferential diffusion (1/2) Preferential diffusion (2/2) Fractals (1/2) Fractals (2/2) Final equation Slide Number 87 Open atmosphere (2/2) Closed vessel 1/3 Closed vessel 2/3 Closed vessel 3/3 Tunnel 78.5 m length Slide Number 93 Slide Number 94 Slide Number 95 Slide Number 96