Performance advantages of transcritical CO2 cycle in the marine environment.

Low-temperature seawater is far away from CO 2 critical temperature, which has significant impacts on the performance of CO 2 closed cycle in the marine environment. The temperature adaptability of CO 2 closed cycle to the marine environment and its performance remain open issues. In this paper, we compare performance advantages of transcritical/supercritical CO 2 cycle based on thermodynamic and dynamic models. Compared with supercritical CO 2 Brayton cycle, transcritical gas-phase CO 2 Brayton cycle exhibits higher thermal efficiency and specific power at low cycle maximum pressure, and its reduced heat load and thermal inertia of regenerator facilitate cycle rapid response. However, transcritical liquid-phase CO 2 Brayton cycle and transcritical CO 2 Rankine cycle demonstrate higher thermal efficiency and specific power at high cycle maximum pressure. Lower compressor inlet temperature causes CO 2 pseudo-critical point to migrate into regenerator, and the intersection point of c p curves of CO 2 on both sides is located within regenerator. This can lead to pinch point and non-physical design within regenerator that inhibits cycle response. It can be avoided by adjusting cycle matching parameters so that the temperature corresponding to intersection point is lower than regenerator hot side outlet temperature. This study provides insights into performance advantages of transcritical CO 2 cycles in marine environments. [Display omitted] • Compare the performance of trans/supercritical CO 2 cycles in marine environments. • Performance analysis based on the cycle thermodynamic and dynamic simulation model. • Transcritical CO 2 cycle performance is more advantageous in marine environments. • Migration of pseudo-critical point to regenerator can inhibit the cycle response. • Avoid pseudo-critical point migration by adjusting cycle matching parameters. [ABSTRACT FROM AUTHOR]