Design and analysis of a novel natural gas liquefaction process based on two-stage ejector-expansion refrigeration cycle

This paper proposes a novel natural gas liquefaction process based on two-stage ejector-expansion refrigeration cycle (T-EERC). Specific energy consumption, exergy efficiency, liquefaction ratio, and total cost rate indexes are applied to evaluate the process. Subsequently, energy, exergy, economic, exergoenvironmental, and exergoeconomic analysis are performed to the T-EERC process. The T-EERC process is capable of producing 47.21 kg/ s of liquefied natural gas (LNG), with a specific energy consumption of 0.2336 kWh/kg, an exergy efficiency of 57.95 %, a liquefaction ratio of 62.94 % and a total cost rate of 0.1562 M$/year, offers a better performance than other natural gas liquefaction processes. The system sensitivity analysis indicates that an increase in the high pressure inlet of the ejector leads to an increase in specific energy consumption for the system and a decrease in exergy efficiency. The energy analysis shows that the heat exchanger HX1 exhibits the lowest energy loss and the maximum heat transfer efficiency. From the exergy analysis, it is found that the total exergy destruction is 30867.43 kW and the greatest exergy destruction was associated with the heat exchangers, the throttles and the compressors. The economic analysis suggests that the total cost rate is more sensitive to fluctuations in the annual interest rate. The exergoenvironmental analysis indicates that the system operates at higher temperatures with less environmental impact. From an exergoeconomic perspective, the maximum cost rate of exergy destruction (720.95$/h) is related to HX5. Furthermore, the exergoeconomic factor of heat exchangers is typically minimal, necessitating supplementary financial outlay to enhance their performance.