Abstract
We present and discuss two-phase flow models to simulate transient flow of CO2-rich mixtures in pipes, which is of relevance for design, operation and safety. The model predictions are compared to data from five depressurization experiments from three facilities. Two flow-model formulations are considered. One is a homogeneous equilibrium model in which the phases travel at the same velocity. The other is a more complex two-fluid model in which the slip between the phases is modelled. The thermodynamic equilibrium of the multi-component mixture, constrained by energy and volume, is computed simultaneously with the flow equations.
In general, good agreement with the experiments is obtained, including the dry-out point where the liquid in the pipe has evaporated. For the friction and heat-transfer models tested, the two-fluid model did not provide substantially better predictions than the homogeneous equilibrium model. The effect of different heat-transfer models is also discussed. In our case, it is necessary to take the pipe heat capacity into account.
In general, good agreement with the experiments is obtained, including the dry-out point where the liquid in the pipe has evaporated. For the friction and heat-transfer models tested, the two-fluid model did not provide substantially better predictions than the homogeneous equilibrium model. The effect of different heat-transfer models is also discussed. In our case, it is necessary to take the pipe heat capacity into account.