Nguyen et al. [
5] recently compared three small-scale LNG systems based on energy and exergy assessment and found that the mixed refrigerant (MR) process is more efficient than the expander-based ones. Khan and Lee [
6] optimized the single mixed refrigerant (SMR) process with the help of the particle swarm paradigm and successfully improved efficiency by reducing the compression energy requirement by 10% compared with the base case. He et al. [
7] optimized and comprehensively compared MSMR and the parallel nitrogen expansion cycle (PNEC) and discovered that MSMR had a lower specific energy consumption, a higher exergy efficiency, a lower total investment, and a higher flexibility than PNEC. Mehrpooya and Ansarinasab [
8] conducted a detailed exergoeconomic evaluation of three popular SMR processes. The results indicated that the most important elements in exergy destruction cost are from PFHEs while the exergoeconomic factor in compressors is higher than other elements. Qyyum et al. [
9] managed to replace the Joule-Thompson (J-T) valves in the SMR process with hydraulic turbines. The replacement saved 16.5% of the required energy and increased the exergy efficiency by 11%. Tan et al. [
10] proposed a new liquefaction process for boil-off gas (BOG) based on the dual mixed refrigerant (DMR) cycle. The new system achieved a coefficient of performance (COP) of 0.25 and an exergy efficiency of 41.3%. Cao et al. [
11] investigated the robustness of the SMR process. They discussed the heat exchange process and the exergy loss in the recuperative heat exchanger and found that the robustness of the mixed refrigerant composition was very strong even though the ratio of the mixed refrigerant was restrained. They also proposed a novel method for adjusting the mixed refrigerant to achieve a higher efficiency.