Hydrogen safety

GexCon R&D is heavily involved in research related to hydrogen safety, including CFD modelling of gaseous and liquid releases, deflagrations and indications for transition to detonation.

Background

The development of applications that use hydrogen as a clean energy carrier has accelerated in recent years. However, hydrogen is a highly reactive fuel, and safe handling and design is critical. Consequence modelling is a critical part of any risk assessment, and it is essential to model the relevant physical processes sufficiently well. CFD tools such as FLACS have the potential to describe the relevant physics reasonably well, but user guidelines and extensive validation work is required. GexCon has been involved in three major hydrogen safety projects:

  • Hydrogen safety project (2001-03) involving a large number of small-scale dispersion and explosion experiments.
  • The EU-sponsored Network of Excellence HySafe (2004-09)
  • International Energy Agency (IEA) Task 19 on Hydrogen Safety (recently renewed).

Validation

Significant validation work, where results obtained with FLACS have been compared with results from various experiments, has been carried out for scenarios relevant to hydrogen safety. The validation studies include dispersion, explosion and combined dispersion and explosion studies. A range of different dispersion experiments is simulated, including low momentum releases, free jets from high-pressure vessels, and LH2 releases. The explosion experiments include smooth and obstructed pipes, a refuelling station, a tunnel, various vented vessels, a jet-ignited lane, etc.

Deflagration-to-detonation transition (DDT)

The possibility of deflagration to detonation transition (DDT) is a significant threat in industries that handle reactive gases, such as hydrogen and acetylene. Dedicated models have been developed and validated to enable FLACS to provide an indication of the possibility of DDT.

Risk assessment

GexCon R&D has also been involved in the development of methodology for quantitative risk analysis (QRA) for hydrogen applications. Such QRAs represent particular challenges due to a large difference in properties of hydrogen and more conventional fuels, such as natural gas or propane: reactivity, flammability limits, buoyancy and transport properties. Case studies have been carried out in tunnels, workshops, and refuelling stations, as well as for hythane (hydrogen and methane mixtures).

Selected references

  • Hansen, O.R. & Middha, P. (2008). CFD-based risk assessment for hydrogen applications. Process Safety Progress 27: 29-34.
  • Middha, P. & Hansen, O.R. (2008). Predicting deflagration to detonation transition in hydrogen explosions. Process Safety Progress 27: 192-204.
  • Middha, P. & Hansen, O.R. (2009). Using computational fluid dynamics as a tool for hydrogen safety studies. Journal of Loss Prevention in the Process Industries, 22: 295-302.
  • Makarov, D., Verbecke, F., Molkov, V., Roe, O., Skotenne, M., Kotchourko, A., Lelyakin, A., Yanez, J., Hansen, O.R., Middha, P., Ledin, S., Baraldi, D., Heitsch, V., Efimenko, M. & Gavrikov, A. (2009). An inter-comparison exercise on CFD model capabilities to predict a hydrogen explosion in a simulated vehicle refuelling environment. International Journal of Hydrogen Energy 34: 2800-2814.
  • Middha, P. & Hansen, O.R. (2009). CFD simulation study to investigate the risk from hydrogen vehicles in tunnels. International Journal of Hydrogen Energy 34: 5875-5886.
  • Venetsanos, A.G., Papanikolaou, E., Delichatsios, M., Garcia, J., Hansen, O.R., Heitsch, M., Huser, A., Jahn, W., Jordan, T., Lacome, J.-M., Ledin, H.S., Makarov, D., Middha, P., Studer, E., Tchouvelev, A.V.,  Teodorczyk, A., Verbecke, F. & van der Voort, M.M. (2009). An inter-comparison exercise on the capabilities of CFD models to predict the short and long term distribution and mixing of hydrogen in a garage. International Journal of Hydrogen Energy, 34: 5912-5923.
  • Middha, P.,Hansen, O.R & Storvik, I.E (2009). Validation of CFD-model for hydrogen dispersion. Journal of Loss Prevention in Process Industries, 22: 1034-1038.
  • Middha, P., Hansen, O.R., Grune, J. & Kotchourko, A. (2010). CFD calculations of gas leak dispersion and subsequent gas explosions: Validation against ignited impinging hydrogen jet experiments." Journal of Hazardous Materials, 179: 84-94.

Additional references

Contact persons:

Prankul Middha: prankul(a)gexcon.com

 

Olav Roald Hansen: olav(a)gexcon.com