Numerical prediction of non-boiling heat transfer in horizontal stratified and slug flow by the Two-Fluid Model

• Phase enthalpy equations have been embedded in the Slug Capturing methodology.
• Slug flow in a horizontal pipe with heat exchanger section has been successfully simulated.
• Good agreement for the pressure drop, hold-up and global two-phase heat transfer coefficient.

Gas–liquid two-phase flow in pipes is frequently encountered in many applications, such as nuclear and oil industries. In the present work non-isothermal intermittent air–water two phase flow in a horizontal pipe is analysed using the one dimensional Two-Fluid Model. Numerical solution is obtained by means of the finite volume method in a high resolution mesh, as in the “Slug Capturing” approach, which is able to predict the evolution of waves in the gas–liquid interface and the transition from stratified flow with subsequent evolution of the slug pattern. Here, the heat transfer problem is embedded in the slug-capturing concept and the ability of the methodology to predict non-isothermal stratified and slug flow is assessed. Simulations were performed for a horizontal pipe including heat exchange with the surroundings. Different operational conditions are examined corresponding to the stratified and slug regime. The predicted pressure drop and global heat transfer coefficient presented a reasonable agreement with empirical correlations and available experimental data. In addition, the mean void fraction and slugs characteristic properties, such as slug and bubble translational velocity, also presented good agreement when compared with correlations available in the literature.

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