Design optimization of a real supercritical CO2 power system for waste heat recovery focusing on heat transfer equipment

The design of heat exchangers strongly affects the overall design of supercritical CO₂ (sCO₂) power systems for waste heat recovery (WHR), being the components with the largest footprint and highest cost. However, the literature often disregards some crucial constraints associated with real applications, such as the heat transfer with dirty flue gas, and rarely explores the economic impact of different pressure drops. This work addresses both gaps with the goal of evaluating the techno-economic potential of sCO2 systems in a real WHR application in the glass industry. The focus is on two sCO2 system configurations that differ for the type and position of the flue gas filtering system: a high-temperature ceramic filter installed upstream the sCO2 system and a low-temperature bag filter installed midway through the heat exchange process. The detailed design of the heat exchangers is based on a bi-objective optimization considering pressure drops and weight as a novel combination of objective functions. Each solution of the Pareto front is subsequently integrated into the design of the total system, and the one minimizing the specific investment cost of the total system is selected. Results show that the configuration with high-temperature filters has an 8.5%-higher specific investment cost compared to the low-temperature filters configuration but allows reducing the volume of heat transfer equipment by 10.8% for the same power output. These findings highlight the trade-off between compactness and investment cost and demonstrate how filtration strategy and pressure-drop management significantly influence the techno-economic feasibility of industrial sCO₂ WHR systems.