Temperature response during rapid depressurization of CO2 in a pipe: Experiments and fluid-dynamics modelling

Abstract

The temperature evolution of ${\text{CO}}_{\text{2}}$ during full-bore pipe depressurization events is relevant for risk assessment, e.g., for ${\text{CO}}_{\text{2}}$ transport in the context of ${\text{CO}}_{\text{2}}$ capture and storage (CCS). We analyse and model the temperature evolution for four different initial temperatures between $T_0=4.6\circ C$ and $T_0=40\circ C$ at supercritical pressures. All the experiments showed an analogous temperature evolution, reaching similar minimum temperatures along the pipe. The warmer the initial temperature, the earlier dry-out and faster temperature recovery was observed. Also, the coldest experiment showed evidence of formation of more dry ice.

We employ the homogeneous equilibrium model (HEM) with different heat-transfer correlations and a two-fluid model (TFM) with different slip models in order to understand the observed data. The results indicate that the heat transfer changes significantly with different thermodynamic states for the ${\text{CO}}_{\text{2}}$. Also, the HEM and the TFM with a RELAP-type friction model performed reasonably well at the outlet and at the closed end of the pipe, but none of the tested models were able to fully describe the strong spatial and temporal gradients observed along the pipe during the depressurization.