Thermodynamic analysis of an integrated transcritical carbon dioxide power cycle for concentrated solar power systems

This paper investigates the thermodynamic performance, through energy and exergy efficiencies, of a conceptual design of a reheat transcritical carbon dioxide (T-CO2) power cycle for concentrated solar power (CSP) plants. Herein, a parabolic trough collector (PTC) solar field is used to harvest solar energy and provide the thermal energy to the T-CO2 power cycle. Thermal energy storage (TES) is also integrated to overcome the intermittent nature of solar energy and maintain stable thermal energy supply to the power cycle. Furthermore, the T-CO2 power cycle is integrated with an absorption refrigeration system (ARS) to enhance the cycle efficiency and production stability by sustaining low condensation temperature at various weather conditions. A parametric study through energy and exergy analyses is conducted considering the performance of each subsystem independently, and that of the overall integrated CSP. The energy and exergy efficiencies, thermal losses, and exergy destruction rates are evaluated under the different design and operating conditions for the T-CO2 power cycle and the ARS. For example, the effects of variations in the maximum cycle temperature and pressure on both the power cycle's energy and exergy efficiencies and integrated system efficiencies are investigated. In addition, the impacts of variations in these parameters on the integrated CSP energy and exergy efficiencies are examined. The T-CO2 power cycle achieved energy and exergy efficiencies of 34% and 82%, respectively. The integrated CSP (solar-to-electric) energy and exergy efficiencies are about 20% and 55%, respectively.