Accidental release of pressurized CO₂ pipeline in carbon capture and storage involves the interaction of phase change and heavy-gas dispersion. However, the effect of the phase change of water vapor in air on the performance of cold CO₂ dispersion is usually neglected. In this study, a three-dimensional two-phase computational fluid dynamics (CFD) model is developed to evaluate the cold CO₂ dispersion by considering the phase change of water. A phase-change model based on the homogeneous relaxation model is used to describe the evaporation and condensation of water. The effects of terrain roughness, atmospheric stability, and turbulence models on the dispersion are also considered. The numerical results show that the model that uses the k–ω turbulent equations is superior to the other models. The results in which the phase change of water is considered exhibit a better agreement with the data from the experiments than those that do not consider it. The model is subsequently used in urban areas, which results in over-predicted CO₂ concentration in the near field and under-predicted CO₂ concentration in the far field when the phase change of water vapor is considered than that when it is neglected. Therefore, we proposed that the phase change of water vapor in the atmosphere should not be overlooked in the more accurate modeling of cold CO₂ dispersion.

碳捕获和储存中加压 CO ₂管道的意外释放涉及相变和重气体扩散的相互作用。然而，空气中水蒸气的相变对CO ₂冷分散性能的影响通常被忽略。在这项研究中，开发了一个三维两相计算流体动力学 (CFD) 模型，通过考虑水的相变来评估冷 CO ₂分散。基于均匀弛豫模型的相变模型用于描述水的蒸发和冷凝。还考虑了地形粗糙度、大气稳定性和湍流模型对弥散的影响。数值结果表明，使用k-ω的模型湍流方程优于其他模型。与不考虑水相变的结果相比，考虑水的相变的结果与实验数据的一致性更好。该模型是在城市地区，这在过预测CO结果随后被用于₂浓度在近场和下预测CO ₂在远场中浓度时的水蒸汽的相变被认为是比当它被忽略。因此，我们提出在更准确地模拟冷 CO ₂扩散时不应忽视大气中水蒸气的相变。