HXL Version 5.0

Heat Exchanger Library 5.0 is part of Modelon's 2026.1 release. New versions of Modelon's libraries are sold and distributed directly from Modelon, as well as approved resellers.

Version 5.0 contains the changes described below.

New features

  • Discretization of refrigerant flow in flat tubes of the same pass is now supported in refrigerant - air flat tube heat exchangers, meaning that all flattubes in a single pass are not considered to have uniform temperature across the different flattubes. This is especially useful to improve the model accuracy for non-uniform air flow or temperature profile in components with many flat tubes per pass. To use the feature, set the "n_orthogonal" parameter to a value > 1. This value is the discretization number per pass of refrigerant flow orthogonal to the refrigerant flow direction (up - down for horizontal passes, left - right for vertical passes). Note that this feature is only supported when refrigerant header volumes are included, so on the Headers tab, the channel including header volumes must be selected for n_orthogonal > 1 to work. Also note that for components with many passes, the model simulation time will quickly increase with increase orthogonal discretization.

Improvements

  • Changes for improved simulation performance and robustness of two-phase fluids:
    • The wall sub-component in heat exchangers now has two temperature states per segment, reducing or removing the need for iterative solving of convection models. The previously used, single temperature state per segment can be brought back if needed by setting the "surfaceState" parameter on the wall sub-component to false.
    • All heat transfer correlations for two-phase fluids now have the option to filter or "relax" the heat transfer coefficients, which can improve simulation performance for transient scenarios. This option can be enabled either for single components by setting the useRelaxation parameter on the "Advanced" tab of correlation parameters, or for all components in a system by including the Modelon.ThermoFluid.Settings_TF component and enabling the useRelaxation parameter there. When enabled, the time constant of heat transfer coefficients can be determined by the parameter "tau". Values in the range of 1 to 10 seconds are recommended.
    • Minor changes to equations in the two-phase flow channel component that reduce risk of simulation slow-down. These changes only affect the transient behavior, not steady-state results.
  • In the parameter record for specifying the initial fluid state for two-phase fluids in all heat exchanger components, the following parameters have been renamed:
    • saturated_in was renamed to give_quality_in
    • saturated_out was renamed to give_quality_out

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