Abstract
Industrial waste heat recovery (WHR) using Organic Rankine Cycle (ORC) systems offers significant potential for enhanced energy efficiency in energy-intensive sectors. However, highly fluctuating heat source conditions result in off-design operation, causing efficiency losses, increased mechanical stress and repeated shutdown events. Integrating thermal energy storage (TES) can mitigate these effects, yet its performance strongly depends on the applied operating strategy and dynamic system behavior. This study investigates the operation of a 2 MWel industrial WHR–ORC system with an integrated packed-bed TES using real plant measurement data. Three storage control strategies (minimum-load prioritization, nominal-load harvesting and ramp-rate smoothing) are evaluated using a two-staged simulation framework consisting of long-term quasi-stationary modeling and detailed dynamic process simulation. The approach enables the evaluation of energy utilization and operational stability under realistic transient boundary conditions. Results show that TES integration significantly improves system operation compared to the baseline without storage. The stability-oriented strategy reduces shutdown events from 1645 to 30 and decreases downtime by 41%, while maintaining a slight efficiency increase. The harvesting-oriented strategy achieves the highest energy utilization with a relative increase of 6%, but with more start–stop events. The ramp-rate strategy provides balanced operation with strongly reduced mechanical stress but slightly reduced energy recovery. The findings demonstrate that storage operation strategy is as decisive as TES size for real industrial applications. The presented methodology provides a framework for designing and controlling TES-assisted ORC systems and supports future techno-economic optimization of industrial waste heat recovery plants.