Energy and exergy assessments of a single flash geothermal and ORC system with packed bed storage using olive pomace

This study presents a detailed analysis of a packed bed thermal energy storage system, supported by a critical review of similar configurations in the literature. The research emphasizes the impact of working fluids on overall system performance. Key parameters including thermal storage capacity, heat transfer mechanisms, pressure drop, air-flow velocity, biomass feed rate, and heat transfer fluid temperature are assessed for their roles in determining system behavior. The main objective is to develop an innovative system that integrates an ORC with a single flash geothermal unit. Thermodynamic assessments, covering both energy and exergy analyses, were performed using MATLin conjunction with the CoolProp library to ensure precise thermophysical property data. Departing from conventional geothermal set-ups, this study introduces a novel ORC-SFGEO integration. While R245fa remains a benchmark working fluid, the study also evaluates low global warming potential alternatives including R1233zd(E), R1234ze(Z), R1234ze(E), and R1234yf commonly used in heat pumps to enhance thermodynamic and environmental performance. Results show that the integrated system yields a 40% performance increase compared to similar systems in the literature. The energy and exergy efficiencies of the base system, without a heat pump, are 24.26% and 7.51%, respectively. When the HPS is integrated, exergy efficiency improves by 55.5%, addressing fluctuations in solar input.