The FLACS simulator, originally developed for natural gas modelling, has been refined by the Bergen-based company GexCon to model hydrogen dispersal. Tests have shown the simulator can predict the outcomes of hydrogen dispersal scenarios very precisely.

FLACS (FLame ACceleration Simulator) is a computational fluid dynamics (CFD) tool for predicting the dispersal patterns of hazardous gases and analysing the risk of explosion. The tool has already earned good standing in the oil and gas industry for simulations of natural gas dispersal.

First natural gas, now hydrogen

Ten years ago, GexCon began further developing FLACS to simulate hydrogen -- and now the model can portray with excellent precision what happens when hydrogen is released, how the gas disperses, and what will happen if it is ignited.

"We have customised FLACS to work just as well for hydrogen as it does for natural gas, even though the two gases have completely different properties," says Olav Roald Hansen, Product Director at GexCon.

GexCon receives funding under the Research Council's Large-scale Programme on Clean Energy for the Future (RENERGI). This support has enabled the company to continue its R&D activities as well as participate in International Energy Agency (IEA) expert groups on hydrogen safety for the periods 2005-2010 and 2011-2013.

"The funding has helped us to establish FLACS as a leading tool for hydrogen safety analyses," says Mr Hansen.

International attention

The Norwegian projects have helped to draw more attention to hydrogen safety in many countries.

"Together, Telemark University College and GexCon have made a substantial contribution to enhancing understanding of hydrogen safety through their cooperation with the IEA," says Stian Nygaard, Adviser in the RENERGI programme.

"Good results like this in the area of safety are essential for gaining acceptance for the widespread use of hydrogen in the transport sector. It's also a plus for a Norwegian product to gain such a strong international foothold."

Tested against reality

One user of FLACS is Sandia National Laboratories (SNL) in the USA, one of the world's top scientific institutions in the field of hydrogen safety. SNL, which receives considerable funding from the US Department of Energy, conducts many large-scale experiments. In 2010, its tests (scaled 1:2.5) on hydrogen dispersal from a vehicle powered by a fuel cell inside a tunnel confirmed FLACS' calculations of full-scale fires.

The FLACS model made its predictions before SNL conducted the dispersal and ignition experiments at the Corral Hollow Experimental Site in California. FLACS' explosion pressure calculations matched the reality almost exactly.

International cooperation proving valuable

GexCon has benefitted greatly from collaborating internationally.

"By participating in the IEA groups, we have gained insight into current international R&D activities," says GexCon's Mr Hansen, "long before they become widely known."

"What's more, we can influence which topics are given most focus in this research, and then plan our own activities accordingly. On top of that, we are made very visible to potential users of FLACS."

Virtual reality

GexCon is currently developing analytical techniques based on virtual reality. "Hydrogen gas and the flames from ignited hydrogen are invisible," explains Mr Hansen. "So there is a risk that people could inadvertently walk straight into the fire. A solution using virtual reality can provide a better picture of critical factors like this."

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