MBL Version 4.5

Modelon Library 4.5 is part of Modelon���s 2024.2 release.

New Features

Modelon.ThermoFluid

  • The two-phase storage tank without walls and all storage tanks with discretized wall now support the "condensation blocking" phenomenon by introducing a saturated surface layer that exchange heat with the vapor and liquid bulk volumes respectively. There is now an additional replaceable heat transfer model selectable to describe the heat flow rate between the liquid surface and bulk. The net evaporation or condensation rate at the surface is determined from the energy balance of the surface layer, and the condensation rate coefficient parameter "K_cond_surface" has been removed. This change isn't backwards compatible, and therefore copies of the previous tank versions have been added to the package "Modelon.ThermoFluid.Volumes.Deprecated". Existing uses of these component will be converted to the deprecated copies if the conversion script is executed.
  • The two-phase storage tanks above also has a new capability to produce vapor in case of boiling at an inner wall surface even if the liquid bulk is subcooled. For this to occur the pool boiling heat transfer correlation must be used for wall - liquid heat transfer. The boiling correlation computes an estimate of how much of the total heat ingress is used for vaporization of liquid. This output is coupled to a new input on the tank volume component that allow distinction between sensible and latent heat in the liquid heat connector.
  • Added ellipsoidal two-phase tank with discretized wall
  • Added variants of all two-phase storage tanks with integrated gas heater in the package Modelon.ThermoFluid.Volumes.TanksWithDetailedWall.WithIntegratedGasHeater. The new variants have a pipe where the internal flow exchange heat with the stored fluid. The exchange is to the liquid or vapor phase depending on wetted area, and is automatically calculated from tank geometry, pipe height from tank bottom and liquid level in the tank. The components have additional parameters for specifying the pipe geometry, initial values and selecting correlations for the internal and external convection or boiling.
  • New Body radiation heat transfer block Modelon.Thermal.Radiation.BodyOptionalShape with the radiation heat transfer coefficient being calculated based on analytical expressions for different geometries. A dropdown list with emissivity values for typical materials has also been added. The block also has an option to enable multi-layer insulation with an arbitrary number of reflective layers between two surfaces.
  • A new simplified Proton-Exchange Membrane (PEM) fuel cell model Modelon.ThermoFluid.FuelCells.Datta2021 includs both sizing/on-design and dynamic performance/off-design capabilities, as well as demonstrative experiment models.
  • Added new evaporation heat transfer and pressure drop correlations for two-phase flow from the work of Arima (Modelon.ThermoFluid.FlowChannels.HeatTransfer.TwoPhase.TwoPhaseArima) and Amalfi (Modelon.ThermoFluid.FlowChannels.PipeResistances.TwoPhase.TwoPhaseAmalfi) which are used by a new chevron plate heat exchanger model in VCL.
  • New single phase pressure drop based on the work of Focke (Modelon.ThermoFluid.FlowChannels.HeatTransfer.SinglePhase.SinglePhaseFocke).
  • Added an air flow source AirFlowSource and an air pressure source AirPressureSourcewith simplified parametrization including relative humidity as input. These models can be used instead of the gas flow/pressure sources if moist air is the only gaseous medium of interest.
  • A new NTU-Eps heat exchanger model Modelon.ThermoFluid.HeatExchangers.EpsNTUFlowbased. This model is suitable for modelling cooling towers and cooling coils by adjusting the heat transfer coefficient (UA) at nominal conditions using correction factors based on mass flow and thermal properties.

Modelon.Mechanics

  • Added RollingWheelWithSlip which enables modeling of longitudinal slip stiffness and slip loss effects in 1D vehicle simulations.

Modelon.Electrical.Differential

  • New components: Conductors, LinkConductor, LoadConductor, Inductors, LinkInductor, LoadInductor, LoadCapacitor, power sensor, power sources.
  • Documentation added to all components.

Modelon.Blocks.Sources

  • Added the new GenericSource block that includes a replaceable source and filter block internally. This block is interface compatible with the Modelica.Blocks.Interfaces.SO constraining class.

Improvements/Changes

Modelon.ThermoFluid

  • Changes for improved robustness at zero flow rate and phase boundary crossings for two-phase fluid flow has been implemented in the two-phase flow channel component, and in flow resistance and heat transfer correlations for two-phase flow. In the flow channel, when computing the fraction of each segment that is in single- or two-phase state, the fluid flow rate is now taken into account such that it does not change abruptly at flow reversal. In correlation models, singularities have been removed at vapor quality 1 and 0, and valid vapor quality range is taken into account to avoid inaccurate asymptotic behavior close to phase boundary. These changes may affect results of existing models when upgrading library version.
  • For two phase tanks the liquid level initialization has been changed from using boolean initFromLevel to the enumeration tankInitQuantity to initialize the liquid level based on level, volume, or total fluid mass.
  • Two-phase tanks now has the option to neglect thermal resistance in the wall. This is recommended for thin pressure vessels, where the majority of thermal resistance lies in the convection layer. Neglecting wall thermal resistance remove the need to iterate on surface temperature, improving speed of simulations.
  • Corrected an error in the Solids.Ellipsoidal_1d_segments component that caused incorrect value for the thermal masses. This fix affect the result of the horizontal tank with spheroidal end caps, as the component is used there.
  • Added surface inclination angle to the interface of convection models. In all two-phase storage tanks, correct inclination angle per segment is pre-set from tank geometry. Inclination angle doesn't have to be set anymore when redeclaring correlations, but must be set when instantiating (drag-and-drop onto model canvas).
  • Improved the robustness of the saturated enthalpy inverse calculation from pressure and temperature for table based media. Previously the calculation could fail with an error message of the form "due to incorrect cell for table". The new method first tries an iterative method if a failure is detected.
  • Added the new normalization by a constant, as an optional transformation method for table based media.
  • Added protection against non-positive values of specific heat capacity at constant pressure when computed from the partial derivative of specific enthalpy from temperature for table based media.

Modelon.Thermal

  • In the pool boiling correlation (composed of convection, nucleate boiling and film boiling correlations), an error was fixed that caused heat flow rate to be zero for the fluid cooling case. The fluid can now be cooled by the surface according to the selected convection model.

Modelon.Utilities.Limits

  • Fixed an issue where the fault action was not triggered as expected.
  • Disable monitoring of the actions that are not used.

Conversion of User Libraries

User libraries will automatically be converted from version 4.4. These conversions are made using the included conversion script: Modelon/Resources/Scripts/Convert_to_4.5.mos.

For two-phase fluid flow models, please note that the changes for improved robustness might affect simulation results.