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Hydrogen Gas Dispersion Studies for a Fuel Cell Vessel (2022)

Jan 11, 2022

The study examines hydrogen gas dispersion in hydrogen vessels, focusing on releases from high-pressure storage tanks, within a Fuel Cell Room, and during vessel refueling. Findings highlight the influence of wind on hydrogen dispersion, the importance of ventilation in preventing hydrogen buildup, and the safety concerns of leaks during refueling.

Hydrogen Gas Dispersion Modeling in Hydrogen Vessels: Key Findings

  1. Introduction:

    • The study focuses on hydrogen gas dispersion in hydrogen vessels using fuel cell technology.

    • Three main scenarios are examined: hydrogen release from high-pressure storage tanks, release within a Fuel Cell Room, and hose failures during vessel refueling.

  2. Hydrogen Release from High-Pressure Storage Tanks:

    • Sandia’s MassTran model was extended to simulate hydrogen release from tanks similar to those on the “Sea Change” and “Discover Zero” vessels.

    • Two tanks can be emptied within 10 minutes, and a ten-tank system can also be emptied in about the same time.

    • The dispersion of released hydrogen is influenced by wind speed and direction. High release speeds are momentum-driven, while slow speeds are influenced by wind direction.

  3. Hydrogen Release in a Fuel Cell Room:

    • Computational Fluid Dynamics (CFD) modeling revealed that the flammable region produced by a hydrogen leak is initially limited by self-induced air recirculation.

    • With active ventilation, hydrogen is evacuated from the Fuel Cell Room, preventing long-term buildup.

    • The room clears of flammable hydrogen/air mixtures within 1.5 seconds after the leak stops.

    • Higher ventilation rates might make leaks harder to detect, depending on the hydrogen alarm's location.

  4. Hydrogen Release During Vessel Refueling:

    • Sandia’s MassTran model was used to simulate refueling a marine hydrogen vessel from a mobile refueling trailer.

    • A tank can be fueled in about 2 hours, considering temperature constraints.

    • Leaks in the refueling hose can pose safety concerns. The size of the leak determines the length of the flammable hydrogen plume.

    • If ignited, the jet flame creates an exclusion zone that could cause burn injuries.

Conclusion: The study provides insights into the behavior of hydrogen gas under various release scenarios in hydrogen vessels. Understanding these dynamics is crucial for safety and efficient operation of hydrogen fuel cell technologies.

Read the report here:

Hydrogen Gas Dispersion Studies for a Fuel Cell Vessel (2022)
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