Comparative energetic analysis of high-temperature subcritical and transcritical Organic Rankine Cycle (ORC). A biomass application in the Sibari district

The present work aims to analyse the energetic performances of Organic Rankine Cycles (ORCs) for small-scale applications. To this purpose, a parametric energy analysis has been performed to define the proper system configurations for a biomass power plant. Saturated and superheated conditions at the turbine inlet have been imposed and subcritical and transcritical cycles have been investigated. Furthermore, the effect of operating conditions and the impact of internal regeneration on system performances have been analysed.Finally, the possible exploitation of the biomass resulting from the pruning residues of peach trees in the Sibari district (Southern Italy) has been evaluated for the ORC configurations optimised during the energetic analysis.The analysis shows that ORCs represent a very interesting solution for small-scale and decentralised power production. Moreover, the results highlight the large influence of the maximum temperature and the significant impact of the internal regeneration on the power plant performances.

► The energetic performances of Organic Rankine Cycles (ORCs) are analysed.
► The effect of working fluid and operating conditions on ORC efficiency are studied.
► Transcritical conditions and internal regeneration produce the maximum performances.
► The possible biomass exploitation in the Sibari district (Italy) has been evaluated.
► The available biomass (7500 t) assures a power output in the range of 0.22–0.57 MWel.