Laboratory of Engineering Thermodynamics (LTD)

Assistant Professorship Electrolyte Thermodynamics and Molecular Simulation

Electrolyte solutions play an important role in many natural processes and technical applications. Recent developments, e.g. in energy supply and storage and mobility, will add to this. A sound knowledge of thermodynamic data of the solutions is thus of utmost importance. For aqueous solutions, different properties are known for many electrolytes, but for other solvents, literature data are typically scarce. Additionally, the data are usually available only for a few state points at or around ambient pressure and temperature. This makes a modeling strategy highly desirable which allows for reliable predictions. Consequently, the following research questions arise:

  • How can key properties be measured if they are not available?
  • How can new models be parameterized in an efficient and robust manner?
  • How strong is the predictive capability of the models?
  • How can the models be integrated in process simulation?

Molecular simulation is a versatile tool for thermodynamic modeling. The model developmet is carried out on the level of intermolecular interactions and thus allows for making predictions based on only few data used for the model parameterization. Molecular simulations can furthermore be used to address a wide variety of questions in mechanical and process engineering. At the LTD, the following topics are investigated:

  • How can reliable molecular models be developed, especially for complex molecules?
  • How much molecular detail do these models need to capture the thermodynamics in a satisfactory manner?
  • Which applications would benefit from a detailed understanding attainable by molecular simulations?
  • How can new simulation methods be devised to make the simulations more efficient?




Junior Professor of Electrolyte Thermodynamics and Molecular Simulation
JP Dr.-Ing. Maximilian Kohns

Research Topics

  • Experimental determination of properties of electrolyte solutions
  • Thermodynamic modeling of electrolyte solutions: GE models, equations of state, molecular models
  • Application of molecular simulations in mechanical and process engineering
  • Development of molecular simulation methods

Selected Projects

Spray Formation and Evaporation in Nanoparticle Synthesis in Spray Flames

Spray flame synthesis is a versatile process for the production of nanoparticles. When burning the solvent of an organic electrolyte solution, nanoparticles form from the metal ions in solution. In the context of the DFG Priority Program 1980, thermodynamic properties of the employed organic electrolyte solutions are measured at the LTD. Based on these data, thermodynamic models are developed, which can then be used in numeric simulations of droplet formation and evaporation. Also the thermodynamic stability is investigated. Due to the large number of possible combinations of solvent and salt which are of interest, methods to predict thermodynamic properties are also tested.

Computer-aided Process Design for Extraction of Valuable Products from Water Streams

In the literature, thermodynamic models are available for aqueous electrolyte solutions containing many different ionic species which allow a reasonable description of certain applications. At the LTD, one such model has been implemented in a simulation program which can be used to predict precipitation of salts from aqeuous solutions. The program can be applied to investigate a wide variety of processes in which precipitation of salts from water streams is carried out. In future work, the model will also be used to specifically design such precipitation processes.

Molecular Modeling and Simulation of Electrolyte Solutions

The characteristic behavior of electrolyte solutions is mainly governed by the strong electrostatic interactions among ions and solvent molecules. The development of molecular models for electrolytes starts directly at this point. By considering this atomistic detail, the structure of the solution is inherently modeled correctly, which, despite lots of effort, is usually described only approximately in other models. Thus, molecular models allow for reliable predictions. However, in some cases, this enhanced detail also requires devising suitable simulation methods. Therefore, at the LTD, new molecular models for electrolyte solutions as well as new simulation methods are being developed.

Physical Modeling of Machining Processes

To date, the molecular level processes governing the influence of the cutting liquid on machining processes is not understood completely. These atomistic processes can be studied in detail with molecular simulations, which also allow for investigating processes separately which occur simultaneously, such as friction and heat transfer. In the context of the IRTG 2057, molecular simulations are carried out at the LTD using model systems in which the influence of several process parameters can be studied systematically. The methods are then applied to models for real fluids and solids.

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