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Exergy Analysis of Organic Rankine Cycles with Zeotropic Working Fluids

Antonio Mariani, Davide Laiso, Biagio Morrone*, Andrea Unich

Department of Engineering DI, Università della Campania “Luigi Vanvitelli” Aversa (CE), Caserta, 81031, Italy

* Corresponding Author: Biagio Morrone. Email:

(This article belongs to this Special Issue: Materials and Energy an Updated Image for 2021)

Fluid Dynamics & Materials Processing 2023, 19(3), 593-601.


Waste heat recovery is one of the possible solutions to improve the efficiency of internal combustion engines. Instead of wasting the exhaust stream of an energy conversion system into the environment, its residual energy content can be usefully recovered, for example in Organic Rankine Cycles (ORC). This technology has been largely consolidated in stationary power plants but not yet for mobile applications, such as road transport, due to the limitations in the layout and to the constraints on the size and weight of the ORC system. An ORC system installed on the exhaust line of a bus powered by a natural gas spark ignition engine has been investigated. The thermal power available at engine exhaust has been evaluated by measuring gas temperature and mass flow rate during real driving operation. The waste thermal power has been considered as heat input for the ORC plant simulation. A detailed heat exchanger model has been developed because it is a crucial component for the ORC performance. The exergy analysis of the ORC was performed comparing different working fluids: R601, R1233zd(E) and two zeotropic blends of the two organic pure fluids. The model allowed the evaluation of the ORC produced energy over the driving cycle and the potential benefit on the engine efficiency.

Graphical Abstract

Exergy Analysis of Organic Rankine Cycles with Zeotropic Working Fluids


Cite This Article

Mariani, A., Laiso, D., Morrone, B., Unich, A. (2023). Exergy Analysis of Organic Rankine Cycles with Zeotropic Working Fluids. FDMP-Fluid Dynamics & Materials Processing, 19(3), 593–601.

This work is licensed under a Creative Commons Attribution 4.0 International License , which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
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