Water Mixtures as Working Fluids in Organic Rankine Cycles

Costante Invernizzi, Marco Binotti, Paola Bombarda, Gioele Di Marcoberardino, Paolo Iora and Giampaolo Manzolini
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Costante Invernizzi: University of Brescia, Department of Mechanical and Industrial Engineering, via Branze 38, 25123 Brescia, Italy
Marco Binotti: Politecnico di Milano, Department of Energy, via Lambruschini 4, 20156 Milano, Italy
Paola Bombarda: Politecnico di Milano, Department of Energy, via Lambruschini 4, 20156 Milano, Italy
Gioele Di Marcoberardino: University of Brescia, Department of Mechanical and Industrial Engineering, via Branze 38, 25123 Brescia, Italy
Paolo Iora: University of Brescia, Department of Mechanical and Industrial Engineering, via Branze 38, 25123 Brescia, Italy
Giampaolo Manzolini: Politecnico di Milano, Department of Energy, via Lambruschini 4, 20156 Milano, Italy

Energies, 2019, vol. 12, issue 13, 1-17

Abstract: This work explores the possibility to adopt in organic Rankine cycle (ORC) plants mixtures of water (acting as solvent) plus an organic compound (acting as solute) as the working fluid. Initially an evaluation of the thermodynamic properties of the mixtures is performed, in order to assess their properties, and to point out the molar fractions which entail a near-azeotropic behaviour. Four species from three different classes of chemical compounds are investigated: 2,2,2-trifluoroethanol and n-butanol for alcohols, where the first is fluorinated, acetonitrile for nitrile class and 2-methylpyrazine as a heterocyclic aromatic compound. Simultaneously, the thermal stability of the pure substances considered as the possible solute for the mixtures is experimentally investigated in order to estimate the temperature applicability range. The ORC plant performance, from a low-enthalpy geothermal heat source (hot water stream from 100 to 200 °C), adopting the selected mixtures as the working fluid is finally evaluated, and the analysis includes a preliminary discussion on the turbine design; results are compared with respect to the reference case of a hypothetical plant adopting water as the working fluid.

Keywords: ORC; working fluids; water mixtures; near-azeotropic mixtures; thermal stability (search for similar items in EconPapers)
JEL-codes: Q Q0 Q4 Q40 Q41 Q42 Q43 Q47 Q48 Q49 (search for similar items in EconPapers)
Date: 2019
References: View references in EconPapers View complete reference list from CitEc
Citations: View citations in EconPapers (5)

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