Methodology for integrated design of fluids and processes using PC-SAFT


Tillmanns, Dominik © Copyright: Lehrstuhl fuer Technische Thermodynamik der RWTH Aachen


Dominik Tillmanns

Energy Systems Engineering


+49 241 80 95376




Molecule Copyright: © LTT

The interaction of working fluid and process is a crucial characteristic of numerous processes in energy engineering and process engineering. In energy engineering, the efficiency of important processes, e.g. chiller, heat pumps or Organic Rankine Cycles, depends on the selected working fluid of the cycle. Important processes in process engineering also depend on working fluids, which are not used for the actual production of the manufactured product, but serve as a chemical auxiliary (e.g., solvents).

Today, working fluid selection and process optimization are carried out separately following a two-stage approach: In a first stage, promising working fluid candidates are preselected based on heuristics and an individual process optimization is performed in a second stage. If the optimal working fluid is not covered by the heuristics, the separation of working fluid selection and process optimization leads to suboptimal solutions and is thus not suitable to ensure a thermodynamic and economic optimal efficiency of the process.

In cooperation with the Institute of Thermodynamics and Thermal Process Engineering of Stuttgart University, a model-based and generally applicable method for integrated design of working fluid and process is developed in this project.



ORC Copyright: © LTT

The aim of this research is the simultaneous optimization of processes and working fluid. Here, the focus of the LTT is on Organic Rankine Cycles, which enable power generation from low-temperature heat.

  Molecular Design Copyright: © LTT

For this purpose, the continuous-molecular targeting computer-aided molecular design (CoMT-CAMD) approach, which is co-developed by the LTT, should be extended. This approach is a completely unique and novel framework in comparison to conventional design approaches. The link between a detailed process model and a thermodynamically consistent fluid model, the PC-SAFT equation of state, enables identifying the optimal working fluid and the corresponding optimal process parameters by optimizing a process-based objective function. The working fluid selection can be performed based on database search or computer-aided molecular design (CAMD). Hereby, novel and promising working fluids can be identified. Consequently, the CoMT-CAMD approach enables to use the full potential of a low-temperature heat source and allows for tailoring a process to the specific application.


Relevant Publications

Schilling, J., Entrup, M., Hopp, M., Gross, J., and Bardow, A. (2021). Towards optimal mixtures of working fluids: Integrated design of processes and mixtures for Organic Rankine Cycles. Renewable and Sustainable Energy Reviews, 135, 110179.

Schilling, J., Horend C., and Bardow, A. (2020). Integrating superstructure-based design of molecules, processes and flowsheets. AIChE Journal, 66(5), e16903.

Lampe, M., de Servi, C., Schilling, J., Bardow, A., and Colonna, P. (2019). Towards the integrated design of Organic Rankine Cycle power plants: A method for the simultaneous optimization of working fluid, thermodynamic cycle and turbine. Journal of Engineering for Gas Turbines and Power, 141(11), 111009.

Schilling, J., Eichler, K., Kölsch, B., Pischinger, S., and Bardow, A. (2019). Integrated design of working fluid and organic Rankine cycle utilizing transient exhaust gases of heavy-duty vehicles. Applied Energy, 255, 113207.

Schilling, J., Tillmanns, D., Lampe, M., Hopp, M., Gross, J., and Bardow, A. (2017). From molecules to dollars: Integrating molecular design into thermo-economic process design using consistent thermodynamic modeling. Molecular Systems Design & Engineering, 2(3), 301-320.

Schilling, J., Lampe, M., Gross, J., and Bardow, A. (2017). 1-stage CoMT-CAMD: An approach for integrated design of ORC process and working fluid using PC-SAFT. Chemical Engineering Science, 159, 217-230.


Project Details

Project Duration

August 31, 2019


This cooperation project together with the Institute of Thermodynamics and Thermal Process Engineering of Stuttgart University is sponsored by the Deutsche Forschungsgemeinschaft (DFG) ( BA2884/4-1 and BA2884/4-2 ).