Comparative optimization and exergy analysis of solar–LNG integrated Rankine cycles among different hot tank outlet temperatures

Abstract

With solar energy playing an increasingly crucial role in the worldwide shift toward renewable resources, a comparative two-objective optimization is performed on a two-tank solar field integrated with an organic Rankine cycle (ORC) and liquefied natural gas under three hot tank outlet temperatures of 200 ${}^{\circ }$C, 250 ${}^{\circ }$C, and 300 ${}^{\circ }$C. Optimization objectives include maximizing the system efficiency and minimizing the electricity production cost (EPC). The comprehensive optimization includes 8 variables, 11 working fluids, and 16 structures, with the results analyzed using the thermodynamic weight. Detailed analysis is further performed on two representative scenarios: the Equal Scenario and the Thermodynamic Scenario. The findings show that the R-ORC is preferred when thermodynamic considerations are the primary focus, whereas the B-ORC is more beneficial when the economic aspect is the main priority. At a hot tank outlet temperature of 300 ${}^{\circ }$C, the Equal Scenario attains 97.81% of the Thermodynamic Scenario‘s system efficiency while reducing EPC by as much as 9.35%. This result demonstrates that a slight sacrifice in thermodynamic performance could yield notable economic improvements. The condenser exhibits the highest exergy loss fraction among all components.