The PSE Model-Based Innovation Prize 2018

Winning paper

Integrated design of ORC process and working fluid using process flowsheeting software and PC-SAFT by Johannes Schilling*, Andre Bardow of RWTH Aachen University, Germany; Joachim Gross of Stuttgart University, Germany.

Published in Proceedings of the IV International Seminar on ORC Power Systems, ORC2017, Italy.


Johannes Schilling Andre Bardow Joachim Gross
Johannes Schilling André Bardow Joachim Gross


Organic Rankine Cycles (ORC) transform low-temperature heat into electrical power. To make best use of a heat source, ORC process and working fluid have to be optimized simultaneously. Thus, integrated design approaches of fluids and processes have been developed. However, integrated design approaches are usually complex and based on specific software tools which prevents fast and easy development of the ORC models. In this work, we have integrated the so-called 1-stage CoMT-CAMD approach into the process flowsheeting software gPROMS ProcessBuilder allowing for integrated design of process and working fluid.

In 1-stage CoMT-CAMD, thermodynamic properties are modeled by the Perturbed-Chain Statistical Associating Fluid Theory (PC-SAFT) equation of state, which we use directly from the gSAFT physical property package. To introduce the molecular structure of the working fluid as an additional degree of freedom within the process optimization, we implemented the homosegmented group contribution approach of PC-SAFT and the Computer-aided Molecular Design (CAMD) formulation of 1-stage CoMT-CAMD in ProcessBuilder. Existing model libraries of ProcessBuilder were adapted to employ the Variable Molecular Structure Compound feature (VMSC) of gSAFT during process optimization. The resulting mixed integer nonlinear program (MINLP) optimization problem is solved by the standard MINLP solver integrated in ProcessBuilder. Thereby, the optimal working fluid and the corresponding optimal process are identified in one single optimization. The resulting tool enables the easy definition of integrated design problems based on the drag-and-drop feature of a process flowsheeting software for ORCs and beyond.

Open Access:


Johannes Schilling*

Johannes Schilling studied mechanical engineering and energy engineering at RWTH Aachen University in Germany and received his master’s degree in energy engineering in 2014. Since 2015, he has been a Ph.D. candidate at the Institute of Technical Thermodynamics at RWTH Aachen University, under the supervision of Prof. André Bardow. Since Mai 2018, he is leading the research group on process design. His research focus is on integrated computer-aided molecular and process design of processes from energy and chemical engineering.

André Bardow

André Bardow studied mechanical engineering and chemical engineering at RWTH Aachen University, Germany, and Carnegie Mellon University, Pittsburgh, PA, and received his Ph.D. in process systems engineering from RWTH. He did postdoctoral research at ETH Zurich and was Associate Professor in the Department of Process & Energy at TU Delft. Since 2010, he has been Professor and Head of the Institute of Technical Thermodynamics at RWTH Aachen University. In 2017, he was also appointed as director at the Institute for Climate and Energy Research (IEK-10) at Forschungszentrum Jülich. His current research integrates energy systems engineering, adsorption-based energy systems, physical property measurements, and computer-aided molecular design with life cycle assessment.

Joachim Gross

Joachim Gross studied chemical engineering at Technische Universität Berlin, Germany, with a study period at University of California, USA. He received his Ph.D. in thermodynamics from TU Berlin. After 4 years in industry, in 2004, he was appointed Associate Professor for Separation Technology in the Department for Process and Energy at the Delft University of Technology. Two years later at the same university, he became Professor and Chair of Engineering Thermodynamics. Since 2010, he is Professor and Director of the Institute of Thermodynamics and Thermal Process Engineering at University of Stuttgart, Germany. His research focuses on molecular thermodynamics, especially on developing predictive method for physical properties, as well as on non-equilibrium thermodynamics and targets the further development of methods for enhancing efficiency of thermal separation processes.

* Submitting author

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