2006 Volume 41 Issue 2 Pages 65-77
A wind tunnel study was conducted to investigate the dispersion of leaked gas from a hydrogen refueling station using a fast-response concentration detector. The station model used in the study was that of a gaseous hydrogen refueling station with onsite hydrogen production. The production capacity was 300 Nm3/hour and the storage vessels were compressed to 40 MPa. The tracer gas, ethane, was mixed with helium gas for buoyancy, and then was released from the compressed storage unit model. For a large leak from a 5mm hole for a 20s gas release time, the gas spread over a wide area downwind and upward. The 4% peak concentration length (Lpeak: the longitudinal distance from the gas source to the boundary of a peak concentration region) extended 24 meters away from the source, the storage building. For a medium leak from a 1mm pinhole, the 4%Lpeak remained onsite at a distance approximately 4m downwind of the source. For a small leak from a 0.2mm pinhole, the 4% Lpeak did not appear clearly downwind from the source. When the gas release time changed from 20s to 3s for the large leak, the 4% Lpeak decreased from more than 24m to 7m. The results suggest that fast leak detection and fast shutdown are very important to minimize risk. A reduction of concentration in the early diffusion stages near the source reduces the 4% Lpeak distance downwind of the source. This result suggests the importance of the ventilation system design in the source storage building.
