New method to connect Aspen Plus with Ansys Fluent CFD simulations

Traditional CFD simulations have been limited by the calculation of thermodynamic properties for uncommon compounds or non-ideal operating conditions. A method of integration of Aspen Plus®, a commercial process engineering simulator, and Ansys Fluent®, a CFD simulator, has been developed.

The method of integration is based in the intercommunication of both programs using Matlab® and Microsoft Excel® VBA as nexus. Ansys Fluent® sends the physical variables (pressure, temperature and composition) to Aspen Plus® which calculates the required properties which are implemented in the CFD simulation.

Figure 1: Mixture of supercritical and subcritical state water. Interconnection of Ansys Fluent® with Aspen Plus® selecting the IAPWS water method in Aspen Plus®. Density evolution profile.

The method of connection of Ansys Fluent® and Aspen Plus® has been validated running two identical CFD simulations selecting firstly the NIST real gas thermodynamic method available in Ansys Fluent® and secondly the IAPWS thermodynamic method (totally comparable with the NIST real gas thermodynamic method) available in Aspen Plus®. The complete agreement between the profiles of the physical properties obtained in both simulations validates the method.

Moreover, the results obtained modeling gas, multicomponent and supercritical systems prove the applicability of the method to any type of fluids at any operating conditions. Finally, it is noted that this subroutine allows modelling refining and petrochemical units since petroleum blends can be defined in Aspen Plus® by the use of pseudocomponents and the modeled streams implemented in CFD simulations.

In conclusion, the possibility of connecting Ansys Fluent® with Aspen Plus® allows expanding traditional uses of CFD to new fields and applications related with chemical and process industries.

Luis Vaquerizo

MINECO and FEDER programs. Project references: CTQ2013-44143-R and CTQ2016-79777-R.  

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