modelPipeFlowVLE_L4_Simple

Information

Purpose of model

A simple model of a pipe flow with a VLE-fluid (Vapor liquid equilibrium) based on the three balance equations of energy, momentum and mass. The mass and the energy balance are dynamic, while the momentum balance is considered static. The balance equations are discretized with a finite volume method. The model uses n+2 fluid models from the TIL media to compute the fluid states at the inlet, outlet, and inside the control volumes of the pipe. Moreover, it uses a replaceable pressure loss model and a replaceable heat transfer model. Therefore, heat and pressure losses are considered. Heat losses are transferred through a heat port if the heat port is connected. However, the heat port doesn’t have to be connected for the model to function. The pipe model can be connected to other models via two fluid ports, which pass the pressure, the specific enthalpy, the mass fraction and the mass flow rate as variables. The model allows reverse flow. In the model are instances of iCom and summary, which are not relevant for the physical understanding of the model.

Level of detail, physical effects considered, and physical insight

L4 (defined in the CodingConventions)

• Heat losses
• Pressure losses
• Thermal inertia
• Variable fluid properties
• Mass storage due to density changes

Limits of validity

The accuracy of the dynamic effects of the model depends on the number of control volumes. The thermal inertia of the pipe wall is neglected.

Interfaces

Governing Equations

The equations have been simplified for easier description of the model.

(for N_cv control volumes)

(for N_cv control volumes)

(for N_cv control volumes)

(The density change is calculated with the TIL media fluid model. Last term is alway zero as the mass fraction doesn't change)

T and rho are determined with the fluid models

References

This model is extended from the ClaRa library. Look at the documentation of the ClaRal library for more information.

Version History

Model was documented by Jan Westphal january 2025 (j.westphal@tuhh.de)

Parameters

Connectors

Components