Energy and exergy investigation of two modified single mixed refrigerant processes for natural gas liquefaction

•Two KSMR processes are investigated via specific power consumption and total exergy destruction rate analysis.•The specific power consumption of the KSMR process is reduced to 0.221 kWh/kg LNG.•Optimization through exergy function resulted in 11.24% decrease in avoidable exergy destruction rate in compressors compared with the optimization via power function.•The second law efficiency of the process is enhanced up to 47.51%.•The process with minimum exergy destruction rate and power consumption is reported.