Paper presented to the 10th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Florida, 14-16 July 2014.
The subcritical Organic Rankine Cycle (SCORC) is widely recognized as a viable technology for converting waste heat to electricity. However, a relative large exergy share is destroyed in the evaporator because of the subcritical heat exchange process. A transcritical cycle has the potential to reduce these irreversibilities in detriment of a financial cost. Therefore the inclusion of financial parameters is crucial for a sound comparison. First, a thermo-hydraulic sizing model for the supercritical ORC is developed. Second, from this model a thermo-economic analysis is provided based on a multi-objective optimization. The Pareto front of net power output versus investment costs are compared for the subcritical and transcritical ORC. Also a single objective criterion, the minimum specific investment cost, is calculated. The results can be used as a guideline to the design of new ORCs.