Optimization and advanced exergy assessment of a propane-free dual mixed-refrigerant LNG liquefaction process

Liquefied natural gas (LNG) production is an energy-intensive process, and mixed-refrigerant cycles dominate industrial applications. This study proposes and optimises a novel propane-free dual mixed refrigerant (DMR) configuration for LNG liquefaction using Aspen HYSYS v14 with the Peng–Robinson EOS. The system eliminates propane to enhance operational safety while maintaining high thermodynamic efficiency. Energy, exergy, and advanced exergy analyses reveal a specific energy consumption (SEC) of 0.29 kW/kg LNG and an exergy efficiency of 67.27 %. The advanced exergy assessment identifies that 68.40 % of total exergy destruction is avoidable, indicating significant potential for further efficiency gains. Comparative benchmarking confirms that the proposed configuration achieves one of the lowest reported SEC values among both propane-based and propane-free DMR cycles. This research provides a technically validated and safer pathway towards sustainable LNG production.