Liquid Cooling Library - Release Information

Version 1.5 contains the changes described below.

New features

  • New visual appearance of all fluid components.
  • It is now possible to visualize the inlet and outlet temperatures in all components directly in the diagram layer by color coding.
  • The valve position of thermostatic valves is visualized in the system model diagram layer.
  • A ball valve model with predicitve geometry based pressure drop has been added.
  • Steady state initialization of systems is facilitated by a new top level parameter for this.
  • Volumetric flow sensors have been added


  • Pump flow curves can now be parameterized by pressure increase in combination with a reference fluid density, in addition to the previously available head option.
  • It is now possible to specify the pump power consumption directly as a table.
  • In heat exchanger models based on tabulated efficiency, it is now possible to specify the efficiency based on a single side instead of true efficiency, which is based on the maximum transferable heat.
  • Transport delay effects have been added to orifice components with a length, i.e. the LongOrifice, Contraction and Expansion. By default this is enabled but existing user models are converted to disable the effect to not impact the result of existing models.
  • It is now possible to disable the transport delay effect in discretized pipe models by a parameter.
  • A robustness improvement in the pump lets the user specify a minimum efficiency. This could otherwise cause unrealisticly high outlet temperatures when operating far outside the validity region for some parameterization options.
  • A robustness improvement has been implemented in the liquid models. The specific heat capacity now extrapolates with constant value outside the validity region of the model. Extrapolation far outside the validity region could previously result in negative specific heat capacity, with unphysical results and simulation craches as result.

Conversion of libraries

    The provided conversion script can perform all required conversions of user models.


    Liquid Cooling Library 1.5 is based on the Modelon Base Library 2.4 and Modelica Standard Library 3.2.2. It has been tested with:

  • Dymola 2016 FD01
  • Dymola 2017


  • Improved compliance to the Modelica language specification 3.3 rev 1.

Fixed bugs

  • Fixed an issue in the pump model that would generate translation errors for certain parameterization options.

Conversion of user libraries

  • User models based on Liquid Cooling Library 1.4 does not need any conversions.


  • Liquid Cooling Library 1.4.1 is based on the Modelon Base Library 2.3 and Modelica Standard Library 3.2.1. It has been tested with:
    • Dymola 2016 FD01
    • Dymola 2016

New features

  • Introduced the possibility to track trace components that are transported in the liquid.


  • Improved Modelica compliance.

Fixed bugs

  • Fixed an error in the thermostatic valve models. The positiveFlow parameter was not propagated to the internal volume component.

Conversion of user libraries

Automatic conversion from Liquid Cooling Library 1.3 is supported using the supplied conversion script.

Base Library

Liquid Cooling Library 1.4 is based on the Modelon Base Library 2.2 and Modelica Standard Library 3.2.1.

New features

  • New component models with geometry based pressure drop correlations: Conical expansion and contraction of pipes.
  • Added heat exchanger stack templates with 7 and 8 included heat exchangers.


  • The simplified heat exchanger components based on efficiency (table based and eps-NTU models) have been improved in that the maximum transferable heat is now correctly computed from the enthalpy difference and flow rates of both sides. Previously this assumed uniform specific heat capacity which in rare cases could result in non-physical solutions.
  • All user calibration factors for heat transfer and pressure drop has been converted from parameters to inputs. Users may still assign them with fixed values in the parameter dialog, but can now also use variable expressions to define calibration factors.
  • Improved flexibility of discretized pipe models. The component can now be configured to expose a flow or control volume behavior at the component boundaries.
  • Table based heat exchangers can now be configured to use table data from file directly from the parameter dialog.
  • Table based heat exchangers now use linear interpolation by deafult instead of Akima interpolation.
  • The aggregate volume base classes have been moved to the Modelon Base Library to allow computation of total liquid volume when the system includes components from other libraries.
  • Improved Modelica compliance.
  • Updated for compatibility with Modelon Base Library 2.1

Fixed bugs

  • Fixed an error in the pump model. Check valve behavior would not work although enabled when used together with enabled mass flow dynamics.

Conversion of user libraries

Automatic conversion of user libraries is supported using the included conversion script.

Base Library

Liquid Cooling Library 1.3 is based on the Modelon Base Library 2.1 and Modelica Standard Library 3.2.1.

Version 1.2.1 of the Liquid Cooling Library is a minor release.


  • Removed comparison of enumeration types with integers, this is not legal Modelica
  • Correcting typos in documentation of heat exchanger stacks
  • Updated for compatibility with Modelon base library 2.0

Base Library

Liquid Cooling Library 1.2.1 is based on the Modelon Base Library 2.0 and Modelica Standard Library 3.2.1.

Version 1.2 of the Liquid Cooling Library is a major update with several new features, bug fixes and other improvements. 

  • Adding more example experiment models. These are found in the Experiments package.
  • Generic pipes, volumes and heat exchanger components inherit the parameter declaration from base classes in the Modelon Base Library to facilitate use of templates.
  • Volume components with any number of connectors, utilizing vectorized connectors and automatic sizing, have been introduced.
  • Table based components now use table look-up blocks from the Modelon Base Library. These utilize the Modelon.DataAccess package and handles more input file formats and table extrapolation options.
  • An arrow indicating the nominal flow direction has been added in twoport volume icons. This should be respected when the positiveFlow parameter is set to true.
  • Some parts of the medium packages that generated warnings during model translation have been updated to reduce the number of warnings. These changes do not affect the simulation results.
  • Improved numerical robustness and simulation performance when using aqueous solutions. The transport property definitions previously generated non-linear systems, which have been solved analytically.
  • Static head can be accounted for by the generic pipe models and geometric models of straight pipes.
  • The expansion volume now uses a gas medium model to define the properties of the gas.
  • Added an experiment template model that defines a replaceable medium model, an aggregate volume component and experiment icon.
  • Added heat exchanger test bench templates with replaceable components and boundary conditions.
  • Visualiztion of the tank liquid level in the component icon.
  • The flow modifier components SetLiquidFlowRate and SetGasFlowRate now also accepts prescribed volumetric flow rates from a parameter or input signal. The input signal may be provided in m^3/s or l/min.

The following medium models have been added to the Liquid Cooling Library:

  • Motor oil, SAE grade 15W-40
  • Jet fuel A
  • Jet fuel A1
  • Jet fuel B

Liquid Cooling Library 1.2 has been updated for MSL 3.2.1

  • The function LiquidCooling.Utilities.Visualizers.Functions.scalarToColor has been removed since the bug in the original version has now been fixed. The function Modelica.Mechanics.MultiBody.Visualizers.Colors.scalarToColor is used instead.
  • New package icons for consistency with MSL.

Version 1.1 of the Liquid Cooling Library is a major update with several new features, bug fixes and other improvements.


Several new internal flow components have been added with geometry based flow resistance models. The loss coefficient data source is D S Miller: Internal Flow Systems, 1990. The added new components are:

  • Straight pipes with circular or rectangular cross section
  • Bend with circular cross section and mitre bend
  • Orifice plate and long orifice
  • Abrupt contraction and expansion
  • Flush mounted intake
  • Combining and dividing T junctions with several different branch angles
  • Symmetrical combining and dividing T and Y junctions

Other new components that have been added include:

  • Heat exchanger stacks, see separate section below.
  • An eps-NTU heat exchanger model with replaceable heat transfer correlations for gas-gas, gas-liquid and liquid-liquid configurations
  • Ideal split and join components, without internal flow resistance
  • Open tank model
  • A thermal mass model with time-varying mass

Medium property models

Medium property models for several liquid phase coolants and refrigerants have been added. The concentration can be set to any value between zero and the eutectic point for the given mixture and is valid between the freezing point and boiling point of the fluid. The data reference is Åke Melinder: Properties of Secondary Working Fluids for Indirect Systems, 2010. (Vapor pressure is currently only available for pure water). The added fluids are aqueous solutions of:

  • Ethylene glycol (Antifreeze, automotive and more)
  • Propylene glycol (Antifreeze and de-icing, automotive and aerospace)
  • Calcium chloride (Brine for refrigeration plants)
  • Ethyl alcohol, or Ethanol (General purpose solvent)
  • Methyl alcohol, or Methanol (Working fluid in low temperature applications, antifreeze in pipelines, solvent)
  • Glycerol (Non-toxic antifreeze, sometimes used in automotive applications)
  • Ammonia (Refrigerant in low temperature applications)
  • Potassium carbonate (Brine)
  • Magnesium chloride (Brine)
  • Sodium chloride (Brine)
  • Potassium acetate (Brine, less corrosive than chloride salts)
  • Potassium formate (Brine)
  • Lithium chloride (Brine, low temperature applications)

With the inclusion of these medium models, the table based water - glycol mixtures at fixed concentrations have been removed. Users are encouraged to use the new medium models as they are based on more reliable data, but the source data of the previous models is still available in the library.

Heat exchanger stacks

Models of simple automotive heat exchanger stack have been added. These are based on the included heat exchanger models and distribute air over the heat exchanger faces based on the covered area fractions which are calculated from the heat exchanger sizes and position in the stack. 3D-visualization allow verification of the stack geometric parameters and animation of the heat exchanger air inlet temperatures, inlet and outlet coolant temperatures and heat transfer. Stack models with 2 - 6 heat exchangers are included.

The component LiquidCooling.Utilities.Visualizers.Components.HXDiagramVisualization has been added to generate a presentation of the resulting heat transfer and temperatures of a heat exchanger directly in the diagram layer. The experiment model LiquidCooling.HeatExchangers.Stacks.Experiments.HeatExchangerStack_4 illustrate its use to present the results of a stack of four heat exchangers. To show the results, the model must be simulated and the diagram layer activated in the simulation mode.

Other new features and improvements

  • An aggregate volume functionality has been added that allows calculation of the total system liquid volume.
  • A table based flow resistance model has been added that takes pressure drop and volume flow pairs as input.
  • A new implementation of the split component gives more robust system models, in particular when the mass flow rate in a branch tends towards zero.
  • A non-critical error in some medium packages that caused warnings in the translation log has been fixed. This leads to a cleaner translation log and significantly reduce the translation time for large system models.
  • The thermostatic valves now have the option to be controlled by an external temperature signal.
  • All included heat exchanger models now extends interface classes that defines different parts of their interface. These are useful as constraining types when building templates or system models, for example they are used in the new stack models.
  • The table based heat exchanger models (gas-gas, gas-liquid and liquid-liquid) have been updated with a constant parameter for efficiency multiplier. This allows quick constant modification of the efficiency without requiring updates of the actual table.
  • Improved the parameter dialog of the gas and liquid pressure sources, only the parameters that affect the fluid properties for the given parameterization option are now enabled.
  • Several "Examples" sub-packages have been renamed to "Experiments" for consistency within LCL and with other Modelon libraries.

Fixed bugs

  • Fixed an error where the parameter for initial temperature in thermostatic valves did not affect the initial valve opening

Conversion of user models from 1.0

Some classes have moved in the library structure or changed name since version 1.0 of LCL. The provided conversion script can perform all required conversions of user models.

Note that users of the table based, fixed water - glycol mixtures will be converted to medium models using IIF reference data.

Base Library

Liquid Cooling Library 1.1 is based on the Modelon Base Library 1.8

This is the first official release of the Liquid Cooling Library.


Liquid Cooling Library (LCL) is targeted to liquid cooling system design with compressible or incompressible flow. It is suitable for a broad range of applications, including automotive, industrial equipment and process industry. Applications include engine cooling, battery thermal management, and cooling of power electrics and industrial equipment.

LCL is suited for pump dimensioning, control of thermal transient response and can be used together with geometry based heat exchanger models from the Heat Exchanger Library (HXL). Users can connect components freely as they desire, which makes it is easy to model non-standard circuits.

Main features

Highlight features of the library are:

  • Efficient incompressible flow models
  • Compressible and incompressible flow
  • Plug and play compatible with other Modelon libraries for thermal management

Base library

Liquid Cooling 1.0 is based on the Modelon base library 1.7.