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ClaRa – Simulation of Clausius-Rankine cycles

ClaRa is a library of power plant components programmed in the modeling language Modelica, which enables the user to simulate transient behavior of power plants and to answer current questions about power plant operation. The library can be downloaded for free.

Download ClaRa
Version 1.3.1 - 06/29/2018
(ZIP file 80MB)

The ClaRa library – Simulation of Clausius-Rankine cycles

ClaRa stands for the Clausius-Rankine cycle. This thermodynamic cycle process is the basis all over the world for electricity generation from the most varied energy sources – from coal-fired power plants to direct steam generation solar power plants. The Modelica library ClaRa enables the investigation of the transient behavior of such cycle processes and is available for free under Modelica License Version 2.0.

Practically oriented

The library has been developed and validated in close cooperation with users from power plant engineering


The component models are validated against reference files and measured data


The structure of the library is laid out so that numerous questions can be processed efficiently


The library can be extended simply and comfortably

Scope of the Library:

  • Turbines, pumps, compressors, condensers, air heaters, steam air preheaters, Ljungström air preheaters, boiler heating surfaces, radiation chambers, combustion chambers, hoppers, valves, non-return valves, three-way valves, electric motors, feedwater tanks , separators, injection coolers, drums, coal mills, mixers, sensors and visualization components, DeNOx plant, desulfurization plant, dust separators, thin- and thick-walled connecting pipework and collectors, material data models for gas mixtures and water.

Advantages of the use of external material data:

  • More robust than Modelica.Media
  • Quicker than Modelica.Media
  • Simpler to extend than Modelica.Media
  • Better support by the various simulator software

Transparency and extendibility

  • The individual models can be interpreted physically and are implemented transparently under Modelica
  • For many models, different degrees of detailing are available for various applications. This enables the production of customized models
  • Important effects like heat transfer or pressure loss can be adapted for a specific case through the use of replaceable models.
  • The library can be extended very simply with new components, even from new areas of application. If you require customized models for our application, please contact us!


The component models are validated using reference data and measured data. In order to ensure a high-quality model, this is done with the collaboration of industrial and academic partners.

The Dyncap and Dynstart projects

The Modelica library ClaRa was developed as part of the joint research project Dyncap (Dynamic investigation of steam power processes with CO2 separation for the provision of control energy).

The research project was carried out as part of the COORETEC Initiative of the German Federal Ministry for Economic Affairs and Energy and had the objective of evaluating the processes necessary for the separation and storage of CO2.

The focus of the investigations was particularly on the dynamic transition behavior of future plants and the question, to what extent power plants with CCS technology can take part in the provision of control energy.

The Dynstart project is a follow up of the Dyncap project and has the goal to evaluate the Dyncap investigations under consideration of extra-low-loads, start-up and shut-down processes with its limits of operation under use of modern control strategies.

Consultant industry partners:

  • E.On Energie AG, Munich
  • Vattenfall AB, Stockholm, Sweden
  • EnBW Kraftwerke AG, Stuttgart

The Dyncap research project was supported by the German Federal Ministry for Economic Affairs and Energy under grant number [03ET2009A-D] from March 2011 to August 2014.

The Dynstart research project is supported by the German Federal Ministry for Economic Affairs and Energy under grant number [03ET7060E] from August 2015 to January 2019.

Institutes & Partners

TLK-Thermo GmbH, Braunschweig

The company TLK-Thermo GmbH has many years of research and development experience in the fields of energy management, vehicle air conditioning and cooling systems as well as modeling and simulation of thermal systems and the development and optimization of controls for the most varied fields of application. The areas of work include energy generation systems, building heating systems and industrial cooling systems as well as the thermal management of alternatively powered cars. TLK Thermo also offers software products for Co-Simulation and post-processing.

To the Website of TLK-Thermo

XRG Simulation GmbH, Hamburg

XRG Simulation GmbH conducts system simulations by numerical methods in the automotive, process and building services field, for the aerospace and shipping industry and for power plants. XRG Simulation is specialized in energy engineering and supports industry and research institutions in research, development and improvement of products and projects. In every phase of the product life cycle XRG Simulation identifies the potential for improvement in a cost effective and time saving way. Moreover, XRG Simulation provides tailored software solutions for analyzing and optimizing products.

To the Website of XRG

Institute for Thermo-fluid Dynamics (TUHH), Hamburg

The Institute for Thermo-fluid Dynamics, Technical Thermodynamics, is involved with the application of the laws of thermodynamics to technical processes. The work is concentrated on the interdisciplinary modeling and simulation of dynamic systems. At the moment, the Institute is working on several research projects in the fields of aviation, cooling and air conditioning, process technology and sustainable energy.

To the Website of the ITT

Institute of Energy Systems (TUHH), Hamburg

In the Institute of Energy Systems, energy processes are technically investigated and optimized. Particular emphasis is placed on the modeling and simulation of realistic constraints, supplemented by trial plants for the implementation of extensive experimental investigations. Fields of research include thermodynamic investigations of different types of power plants and CCS technologies with respect to flexibility and part-load operation.

To the Website of the IET


  • [1] Johannes Brunnemann , Friedrich Gottelt, Kai Wellner, Ala Renz, André Thüring, Volker Röder, Christoph Hasenbein, Christian Schulze, Gerhard Schmitz, Jörg Eiden: „Status of ClaRaCCS: Modelling and Simulation of Coal-Fired Power Plants with CO2 capture“, 9th Modelica Conference, München, 2012 // Download (pdf)
  • [2] Volker Roeder, Christoph Hasenbein, Alfons Kather, Kai Wellner, Gerhard Schmitz, Johannes Brunnemann, Friedrich Gottelt, Ala Renz, Christian Schulze, André Thüring: „Das Projekt DYNCAP: Untersuchung des dynamischen Verhaltens von Dampfkraftprozessen mit CO2-Abtrennung zur Bereitstellung von Regelenergie“, Proceedings of the 44th Conference on Power Plant Technology, Dresden, Oktober, 23–24, 2012
  • [3] Alfons Kather, Volker Roeder, Christoph Hasenbein, Gerhard Schmitz, Kai Wellner, Friedrich Gottelt, Lasse Nielsen: „DYNCAP Dynamische Untersuchung von Dampfkraftprozessen mit CO2-Abtrennung zur Bereitstellung von Regelenergie“, Abschlussbericht, Technische Universität Hamburg-Harburg, TLK-Thermo GmbH, XRG Simulation GmbH, 2015 // Download
  • [4] Friedrich Gottelt, Kai Wellner, Volker Roeder, Johannes Brunnemann, Gerhard Schmitz, Alfons Kather: „A Unified Control Scheme for Coal-Fired Power Plants with Integrated Post Combustion CO2 Capture“ Proceedings of the In 8th IFAC Conference on Power Plant Power System Control, Toulouse, Frankreich, 2012
  • [5] Marcel Richter, Florian Möllenbruck, Andreas Starinski, Gerd Oeljeklaus, Klaus Görner: „Flexibilization of coal-fired power plants by Dynamic Simulation“ Proceedings of the 11th Modelica Conference, Paris, 2015 // Download (pdf)
  • [6] C. Gierow, M. Hübel, J. Nocke, E. Hassel: „Mathematical Model of Soot Blowing Influences in Dynamic Power Plant Modelling“ Proceedings of the 11th Modelica Conference, Paris, 2015 // Download (pdf)
  • [7] Friedrich Gottelt, Timm Hoppe, Lasse Nielsen: „Applying the Power Plant Library ClaRa for Control Optimisation“ Proceedings of the 12th Modelica Conference, Prag, 2017 // Download (pdf)