An evaluation of vaporization models for a cryogenic liquid spreading on a solid ground

The spreading and vaporization of a hazardous cryogenic liquid due to its accidental release on solid ground may result in a pool fire, an explosion, or a hazardous vapor cloud. Many mathematical models have been built to predict the spreading and vaporization of a liquid pool. To determine the heat flux from the ground to the liquid pool two boundary conditions (BCs) at the ground surface have been commonly used: (i) specified heat flux and (ii) specified temperature. The first BC is derived from predictive correlations for boiling heat transfer regimes (BR-BC) that are dependent on the temperature difference between the liquid and the ground surface, while the second is based on an assumption of perfect thermal contact (PTC-BC) between the liquid and the ground. However, the influence of the selection of these BCs on the model predictions still needs to be investigated. To this end, we implemented both types of BCs in liquid spreading models and then compared the results. In addition, experiments were conducted for liquid nitrogen (LN2) and liquid oxygen (LOX) to observe pool spreading and pool regression. The PTC-BC was in better agreement with the experimental results than the BR-BC. At the initial stage, the BR-BC underestimated the vaporization velocity and over-predicted the pool radius because the boiling regime correlations did not account for the effects of the radial flow. The two BCs agreed well at the later stages. It is recommended that the PTC-BC should be used for a spreading pool while the BR-BC should be used for a non-spreading pool. (C) 2019 Published by Elsevier Ltd.