Comparative analysis of the effects of expander types on thermodynamic performance in low-temperature waste heat recovery systems (ORC)

The growing global demand for energy efficiency has underscored the significance of recovering industrial waste heat. The Organic Rankine Cycle (ORC) stands as the most prevalent method for transforming low-temperature heat sources into electrical energy. This research examines expander technologies, which have a direct impact on the performance of ORC systems. A comparative analysis is conducted between dynamic-type (radial turbine) and volumetric-type (scroll) expanders, focusing on thermodynamic efficiency, operational ranges, and mechanical design limitations. The review concludes that turbines provide efficiency benefits at higher power outputs (exceeding 50 kW), while scroll expanders are more appropriate for small-scale applications (under 10 kW) and fluctuating flow conditions, mainly due to their ability to tolerate liquid presence and their lower cost.