Energy, Economic, and Environmental Evaluation of Supercritical Carbon Dioxide Brayton Cycles for Waste Heat Recovery in a Natural Gas Engine

In this investigation, a comparison of three various S – CO2 Brayton cycle designs, configuration A (simple regeneration cycle), configuration B (recompression cycle), and configuration C (partial cooling cycle), used for waste heat recovery in a natural gas engine, has been made. During the experimental tests, the engine has been operated under four operating conditions (40%, 60%, 80%, and 100%). The research includes energy, exergy, economic, and environmental analysis of the various Brayton cycles. Configuration B stands out for having the lowest exergy destruction rate. The results show a reduction of 37.30% and 34.91% compared to configuration A and configuration C. On average, configuration B increases 12.02% and 3.95% in energy efficiency compared to configuration A and configuration C. Additionally, configuration B allows a 9.44% and 5.94% increase in energy efficiency over the previous Brayton cycles. The economic analysis indicates that configuration A presents the best economic benefits. It shows a 34.50% and 42.96% reduction in electrical production cost compared to configuration B and configuration C. However, configuration B causes the least environmental impact, achieving a reduction of 36.49% and 28.34% compared to configuration A and Configuration C. In general, configuration B is considered the best configuration due to its better energy and energy efficiency, as well as its lower environmental impact.