Evaluations of energy, exergy, and economic (3E) on a liquefied natural gas (LNG) cold energy utilization system

The LNG cold energy utilization system primarily integrates additional power cycles during the gasification process to harness the cold energy released in this process efficiently. This study introduces a combined cooling and power (CCP) system, which comprises a cascade organic Rankine cycle (ORC), an air conditioning refrigeration (ACR), and a direct expansion cycle (DEC). Furthermore, the thermodynamic and economic analyses of the CCP system were evaluated, and the optimization of each influence parameters was performed by the genetic algorithms, such as the composition of the quaternary mixed working fluid (Methane: Ethane: Propane: i-Butane), condensation pressure, evaporation pressure, and the first-stage expansion pressure within the system. According to the simulation results, the suggested overall exergy destruction of the CCP system proposed by this work is reduced by 13.18% under optimized conditions, with a maximum net power generation of 230.38 kW and an exergy efficiency of 45.58%. Economic analysis reveals that the system's investment cost, annual economic benefits, and levelized energy cost are 2.02 × 106 $, 2.75 × 105 $, and 0.10 $/kWh, respectively. With the system's official operation, the investment cost will be recovered within 8.61 years.