Numerical Investigations of Hydrogen Release and Dispersion Due to Silane Decomposition in a Ventilated Container

In recent years, new chemical release agents based on silane are being used in the tire industry. Silane is an inorganic chemical compound consisting of a silicon backbone and hydrogen. Silanes can be thermally decomposed into high-purity silicon and hydrogen. If silane is stored and transported in Intermediate Bulk Containers (IBCs) equipped with safety valves in vented semi-confined spaces, such as ISO-Containers, hydrogen can be accumulated and become explosive mixture with air. A conservative CFD analysis using the GASFLOW-MPI code has been carried out to assess the hydrogen risk inside the vented containers. Two types of containers with different natural ventilation systems were investigated under various hypothetical accident scenarios. A continuous release of hydrogen due to the chemical decomposition of silane from IBCs was studied as the reference case. The effect of the safety valves on hydrogen accumulation in the container which results in small pulsed releases of hydrogen was investigated. The external effects of the sun and wind on hydrogen distribution and ventilation were also evaluated. The results can provide detailed information on hydrogen dispersion and mixing within the vented enclosures, and used to evaluate the hydrogen risks, such as flammability. Based on the assumptions used in this study, it indicates that the geometry of ventilation openings plays a key role in the efficiency of the indoor air exchange process. In addition, the use of safety valves makes it possible to reduce the concentration of hydrogen by volume in air compared to the reference case. The effect of the sun, which results in a temperature difference between two container walls, allows a strong mixing of hydrogen and air, which helps to obtain a concentration lower than both the base case and the case of the pulsed releases. But the best results for the venting process are obtained with the wind that can drive the mixture to the downwind wall vent holes.