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CFD simulations in Other Applications

Hydrogen dispersion experiments in a half-scaled hallway and subsequent CFD validation using the FLUENT code were performed by Swain (SwainMR:1999). Hydrogen leaked at a rate of 2 SCFM (0.94 lt/s) from the floor at the left end. At the right end of the hallway, there were a roof vent and a lower door vent for the gas ventilation. Four sensors were used to record the local hydrogen concentration variations with time. Predicted hydrogen concentrations time series were found in good agreement with the experimental data. The same experiments were simulated by Agranat et al. {[DB, AgranatV:2004]], using the PHOENICS code. Predicted results were found similar to the ones obtained using the FLUENT code with maximum concentration differences between the two models of about 20%.

Catastrophic hydrogen releases inside the Alpha H2BPS (H2 Backup Power System by Stewart Energy) generator room were simulated by Agranat et al. (AgranatV:2004) under real industrial working scenarios and real geometry, using the PHOENICS code and the LVEL turbulence model. Two scenarios were considered in the simulations: a vertical fast release from a high-pressure line and a horizontal fast release from a medium-pressure line. The CFD simulations showed that the two installed sensors are capable of detecting 10% LFL cloud (0.41%) separately at 8.8 and 9.7 seconds for the high-pressure vertical leak, but only one sensor which is closer to the leak orifice can detect the same concentration cloud within 20 seconds for the medium-pressure horizontal release. The numerical simulation confirmed that the current sensor installation can promptly report the potential catastrophic hydrogen leak under the above scenarios. However, the fact that 10% LFL hydrogen cloud cannot reach one sensor during the horizontal release indicates that the sensor location can be further optimized and more sensors are required for the systems.

The method for determination of maximum ventilation described in the standard IEC EN 60079-10 was validated by Nilsen et al. (NilsenS:2004) for a small hydrogen production (by water electrolysis) unit located inside two different enclosure geometries, using the FLACS code for dispersion and the PHAST code for release. It was found that the model suggested in standard IEC EN 60079-10 is not a conservative approach when deciding the ventilation capacity large enough to keep flammable gas clouds at a negligible size and therefore must be used with care.


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Page last modified on December 05, 2008, at 10:33 AM