Thermodynamic Modelling and Split Fraction Optimization for Sco2 Recompression Power Cycle

Supercritical carbon dioxide (sCO2) power cycle is the emerging technology for next generation nuclear reactors. Brayton cycle using supercritical carbon dioxide as working fluid is an innovative concept for converting thermal energy into electrical energy and beats the conventional thermal power generation cycles because of its compact turbomachinery, enhanced safety, and cycle efficiency. Among the several promising layouts of sCO2 cycle, recompression cycle is the most attractive in terms of cycle efficiency as it uses a fraction of the flow and recompression is performed without rejecting heat in the environment. This paper presents an investigation and optimization of a recompression supercritical carbon dioxide cycle. A thorough analysis has been carried out to understand the effect of significant parameters such as recompression fraction ratio, inlet pressure to the main compressor, effectiveness of the high temperature recuperator (HTR) and low temperature recuperator (LTR) on the cycle efficiency. An iterative approach is used to measure the state point conditions for all the cycle components. The optimization of the recompression fluid fraction has also been performed which shows that a maximum cycle efficiency of 45% is achieved with a mass fraction of 0.80 with 7500kPa main compressor inlet pressure. Keywords: Supercritical Brayton cycle, Carbon dioxide, Recompression.