Thermodynamic Analysis of an Energy Recovery System in High Power Thermal Engine Based on a Supercritical CO2 Brayton Cycle

Internal combustion engines have limited efficiency and high environmental impact due to polluting emissions from the use of fossil fuels. To expect that in recent years significant improvements in their efficiency and emissions have been achieved, the maximum efficiency of these thermal machines is around 40%. In this study, a proposal of an energy recovery system in the exhaust stream of a high-power natural gas Genset using a Brayton cycle with supercritical CO2 is presented. In order to study the viability of the system, a thermodynamic analysis is carried out to study the influence of operational parameters on variables of the Brayton cycle as energy efficiency and destroyed exergy in the different components. On the results obtained, an optimization process has been carried out to improve the proposed energy recovery system. For this reason, the set of operational parameters of a coupling cycle has been found using a vortex tube, so the potential of the use of the exhaust gases will be increased, identifying an improvement of 14% in the heat available for the recovery process and a 3.8% improvement in the overall efficiency of the system. It has been identified that it has been possible to recover 5.3% of the operating power of the engine with the proposed system, allowing reducing specific emissions, and improving the performance of the thermal machine.