Hydrogen jet explosion: New tests, blast, and fireball models

Delayed ignition of a hydrogen jet release from a vent or accidental release can lead to a jet explosion with blast and thermal hazards. Such hazards should be accounted for in vent stack design and separation distances and when performing an overall facility risk assessment. The authors, with others, have previously presented a model for predicting the jet explosion blast overpressure for high‐pressure choked hydrogen releases at warm temperatures. The jet explosion phenomenon was subsequently observed during lower pressure non‐choked releases, with an initial fireball that extended downwards below the release elevation. To investigate the non‐choked jet explosion and fireball phenomenon, Air Products and BakerRisk conducted more than 20 delayed ignition hydrogen jet release tests over a wide range of release velocities and temperatures. Moreover, new engineering models were developed to predict blast overpressures and initial fireball dimensions due to a hydrogen jet explosion. This paper presents the new test data, a comparison with computational fluid dynamics (CFD) predictions, and the new models for blast overpressure and fireball predictions.