Gexcon to present at 1st International Conference on Fires & Explosions in the Process Industry

Title: Improvement of the EFFECTS dispersion model for under-expanded turbulent jets

Author: Andreas Mack, Hans Boot

Presenter: Andreas Mack

Date & Time: Tuesday, 10 October 2023 at 11:10 – 12:50 (CEST)

Abstract:

The transition from fossil fuels to renewable alternative energy carriers (such as hydrogen and ammonia) will play an important role in reducing global CO2 emissions and supporting the energy transition. Therefore, it is expected that these energy carriers will be produced, transported, and used at large scale in the future. In order to estimate the consequences and risks due to the accidental release of these new energy carriers, the models applied to these assessments need to be able to properly simulate the unique behaviour of these new energy carriers, which can present strong buoyant behaviour when released into the ambient air.

Gexcon’s consequence modelling tool EFFECTS contains different dispersion models for neutral and heavy gas dispersion, which are based on a 1-D discretisation. Since the code was developed in the past with a focus on heavy or neutral gas conditions the simulation of buoyant jets and plumes so far was limited.

Recently, the dispersion model in EFFECTS has been updated and extensively validated for light gas situations including jet releases and lifting plumes. In the present paper, the modifications for gaseous turbulent jets will be discussed. This includes the full release velocity range from low subsonic to supersonic flow under highly under-expanded conditions which are highly relevant for the high-pressure storage of hydrogen. In particular, a new model for the calculation of the expanded diameter in combination with a reviewed Chen and Rodi model has been implemented.

The models have been validated against a wide range of experimental classical and recent data sets including concentration and velocity data. This also includes a wide range of initial densities from lighter than air to heavy gas which will be discussed in the paper. The simulations show excellent agreement with experimental data resulting in less conservative predictions compared with the previous models.

Literature:
[1] Han, S.H., Chang, D., and Kim, J.S.: Release characteristics of highly pressurized hydrogen through a small hole, International Journal of Hydrogen Energy, 38(8), pp.3503-3512, 2013