Conceptual design and parametric study of combined carbon dioxide/organic Rankine cycles

Nowadays, nuclear energy is one kind of effective and clean energy resource. Supercritical carbon dioxide cycle proves to be a promising way of energy conversion for future nuclear power plants. In this paper, a CO₂ recompression cycle and a partial-cooling CO₂ cycle are presented. And the thermodynamic analyses of two above-mentioned cycles are discussed. The parametric analysis is conducted to examine the effect of some key parameters on the cycle performance. Moreover, four combined CO₂/organic Rankine cycles are presented and optimized with the thermal efficiency and the exergy efficiency as their objective functions by means of genetic algorithm (GA) under the given conditions. And then the performance analysis is conducted for the optimal combined cycle. The results show that under one certain condition (P_max = 20 MPa, TIT = 550 °C), the partial-cooling CO₂ cycle is the optimal stand-alone CO₂ cycle, and the combined simple CO₂/organic Rankine cycle is proved to be the optimal combined cycle for utilizing nuclear power.