Energy, Exergy, and Environmental Analysis of Organic Rankine Cycle Systems for Industrial Waste Heat Recovery Applications

In the context of energy transition and the search for sustainable industrial solutions, waste heat recovery is a promising strategy to improve energy efficiency and reduce greenhouse gas emissions. This study investigates the integration of Organic Rankine Cycle (ORC) systems for waste heat recovery through a comprehensive 3E (energy, exergy, and environmental) analysis. A Python 3.10-based simulation framework was employed to model ORC performance under varying operating conditions and working fluids. Two case studies were considered: (i) a metallurgical application (specifically, an aluminium production plant) and (ii) two large marine engines (Man S60-MC6 and Wärtsilä 46DF), evaluated in electricity-only and combined heat-and-power (CHP) modes. Results show that neopentane is the optimal fluid for the aluminum industry, achieving 3.5 MW of net power output with zero environmental penalties. For marine engines, efficiency gains reached 7–8% for the Man engine and over 10% for the Wärtsilä engine in electricity mode, with thermal efficiencies exceeding 35% under CHP operation. The study demonstrates the relevance of ORC systems for the energy recovery of waste heat and the integration of sustainable technologies into industrial processes. It helps improve energy efficiency, reduce environmental impact, and support the energy transition by recovering waste heat.