Analysis of exergy efficiency, exergy economy and exergy environment(3E) in the cascade utilization of LNG cold energy

To enhance LNG cold energy recovery, minimize environmental impact, and improve the economic performance of the system, a multi-objective optimization method based on the NSGA-II genetic algorithm was employed. A poly-generation system integrating LNG cold energy recovery, a Three-stage Rankine cycle(ORC), carbon capture, and cold-chain refrigeration was proposed. By optimizing parameters such as turbine inlet temperature, condensation temperature, and working medium flow rate, the system 's exergy efficiency increased from 45.5% to 50. 1%, unit electricity cost decreased to 4.6 ＄/GJ, CO₂ emissions were reduced from 40 kg/GJ to 30 kg/GJ. These results demonstrate that the integrated poly-generation system significantly improves energy efficiency, reduces environmental impact and operating costs, and offers a promising solution for efficient energy utilization and sustainable development.