Analysis of data from spilling experiments performed with liquid hydrogen

A CFD study of the effects of combined impurities, ground temperature, and topography upon the consequence distances and plume shapes generated by CO2 release from CCS pipeline failure

In the carbon capture and storage (CCS) infrastructure, the risk of a high-pressure buried pipeline rupture possibly leads to catastrophic accidents due to the release of tremendous amounts of carbon dioxide (CO₂). Therefore, it is crucial to conduct an in-depth study on CO₂ atmospheric dispersion when developing CO₂ pipeline. In fact, the CO₂ captured from diverse industrial processes may contain a variety of impurities. The combined effect of the toxicities of the multiple impurities increases the risk, which has usually been ignored by previous studies. In this paper, computational fluid dynamics (CFD) technology is applied to investigate the influence of hazardous chemicals on CO₂ stream dispersion under different meteorological, complex terrain features, and ground temperature condition. In addition, the effect of combined toxic impurities on consequence distance was also investigated comprehensively. It was found that complex conditions affected the near-surface flow field, and obstacles enhanced the lateral dispersion of CO₂. Compared to 288 K ground temperature, the plume area inside the 50,000 ppmv CO₂ boundary decreased by 8.2%. The hazardous effects of combined toxic impurities became significant compared to a single toxic impurity. This study may furnish a viable assessment technique for the risks associated with CCS.

Investigation of entrainment and thermal properties of a cryogenic dense-gas cloud using optical measurement techniques

Cryogenic dense-gas clouds have been investigated in a heavy-gas channel under controlled source and ambient conditions. Advantage is taken from new, non-intrusive optical measurement techniques (e.g. image correlation velocimetry, ICV, and background oriented Schlieren, BOS) providing detailed pictures of the temperature and velocity field in relevant regions of the cloud. The ice particles in the cloud, formed by nucleation, represent a natural seeding to be used as tracers, which have the advantage of behaving passively. Two layers can be identified in a cryogenic gas cloud: a lower cold layer, which is visible due to the presence of ice particles, and an invisible upper layer, where the ice particles have melted, mostly due to heat addition by air entrainment into the upper layer. A two-layer model has been applied to a generic element of the cloud, where detailed experimental data regarding velocity and temperature are available. Thermal- and dilution behaviour can be interpreted by means of the model which is presented in detail. A global entrainment parameter is deduced allowing a simple comparison with existing experimental information obtained by other traditional experimental techniques. The numerical values of the present entrainment parameter agree well with the correlations proposed by other authors. Thermal effects, such as heat transfer from the ground, appear to be very important. In addition, the visible height of the cloud can be predicted in relative good agreement with the experimental observations, by means of a thermal balance including the phase transition of the ice particles.