Exergetic Analysis of a New Direct Steam Generation Solar Plant Using Screw Expanders

Paolo Iodice, Giuseppe Langella and Amedeo Amoresano
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Paolo Iodice: Dipartimento di Ingegneria Industriale, Università degli Studi di Napoli Federico II, 80125 Napoli, Italy
Giuseppe Langella: Dipartimento di Ingegneria Industriale, Università degli Studi di Napoli Federico II, 80125 Napoli, Italy
Amedeo Amoresano: Dipartimento di Ingegneria Industriale, Università degli Studi di Napoli Federico II, 80125 Napoli, Italy

Energies, 2020, vol. 13, issue 3, 1-19

Abstract: Screw expanders are volumetric machines particularly suitable in energy conversion with steam–liquid mixtures and for the exploitation of low temperature heat sources. This study explored the main criteria to evaluate the thermodynamic advantages and exergetic assessment of an innovative solar electricity generation system: Screw expanders are utilized as power machines and parabolic trough collectors as a thermal source. Such a direct steam generation solar system, which is based on the Rankine cycle, offers benefits in comparison with usual power plants with dynamic expanders: The best exploitation of low temperature heat sources, satisfactory thermal efficiency with steam–liquid mixtures, lower evaporation pressures, and reduced size. Under real working conditions, screw expanders can work at part-load operating conditions; thus, the chief purpose of the present paper was to analyze the exergetic advantages of the planned solar power system when solar radiation and off-design working conditions fluctuate. Initially, the polytropic expansion phase with a specific numerical model is described to evaluate the energy losses that affect the thermodynamic performance of screw expanders when installed in the planned renewable energy power plant. Subsequently, to explore the exergy harnessing in the exhausted steam at off-design working conditions and then to appraise the maximum exergetic efficiency of the proposed screw expander-based solar thermal electricity plant, numerical optimization was performed in a broad range of evaporation and condensation temperatures.

Keywords: steam screw expander; part-load behavior; exergetic analysis; polytropic expansion phase (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: 2020
References: View references in EconPapers View complete reference list from CitEc
Citations: View citations in EconPapers (3)

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