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Session: Poster session & Sponsor Exhibition
Session starts: Monday 07 October, 14:00

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Akshay Hattiangadi (Process and Energy Dept., Delft University of Technology)
Tiemo Mathijssen (Process and Energy Dept., Delft University of Technology)
Matthias Lampe (RWTH Aachen University, Lehrstuhl fur Technische Thermodynamik)
David Pasquale (Dip. di Ingegneria Meccanica e Industriale, Universita' di Brescia)
Joachim Gross (Universitat Stuttgart, Institut fur Technische Thermodynamik und Thermische Verfahrenstechnik,, )
André Bardow (RWTH Aachen University, Lehrstuhl fur Technische Thermodynamik)
Piero Colonna (Process and Energy Department, TU Delft)

Abstract:
The selection of a working fluid is key to the design of an Organic Rankine Cycle (ORC) system, given the energy source, sink and the power capacity. Up to now the selection of the working fluid is mainly guided by experience and the use of several system simulations. In the attempt to approach the engineering problem in a more systematic way, a software tool has been developed which simultaneously optimizes the energy conversion process and selects the optimum working fluid for a given heat source. The program is based on a framework that uses a continuous-molecular targeting approach which allows for an integrated working fluid and system design \cite{bardow2010continuous} \cite{lampe2012}. The steady-state process is simulated with an in-house program for thermodynamic analysis and optimization of energy conversion systems\cite{cycletempo}. The system model includes a simple model of a radial turbine. Given constrained operating conditions, the ORC system is optimized simultaneously with the molecular parameters defining the fluid properties according to PC-SAFT equation of state\cite{gross2001perturbed}. The optimizer is provided by a state-of-the-art optimization suite \cite{nexus}. The working fluid is selected by comparing the optimized molecular parameters to the ones of real fluids.\\ The procedure has been preliminarily tested using as an example the specifications of a waste heat recovery ORC turbogenerator for truck engines \cite{Lang2013AssessmentWasteHeat}. The choice of the working fluid is restricted at the moment to siloxanes. The preliminary design of the turbine governs the optimization. The turbine has been modeled by applying the methodology described by Whitfield and Baines \cite{whitfield1990}. Future work will be devoted to the implementation of refined component models and to the extension of the fluid selection to other organic fluid classes.