Amirkabir University of Technology Amirkabir Journal of Mechanical Engineering 2008-6032 52 9 2019 03 27 Optimization and Thermodynamic Analysis of the Dual Mixed Refrigerant Process of the Natural Gas Liquefaction Optimization and Thermodynamic Analysis of the Dual Mixed Refrigerant Process of the Natural Gas Liquefaction 2357 2368 3358 10.22060/mej.2019.15191.6054 FA Mohsen Kashi Parpinchi Imam Khomeini international university, Qazvin, Iran Alireza Sadeghi mam Khomeini international university, Qazvin, Iran Mansour Khanaki Imam Khomeini International University Seyed Abbas Sadatsakak Imam Khomeini International University Journal Article 2018 10 27 Natural gas liquefaction processes require a lot of investment and operation costs and are part of the energy-consuming industries. In this research, parameters such as refrigerant component, inlet and outlet pressure to compressors were optimized in the dual mixed refrigerant system to reduce operating costs. The optimized system was then evaluated by exergy to obtain the amount of exergy loss in various components of the system, finding illustrate the highest exergy losses were in compressors, heat exchangers, aftercoolers and throttle valves, respectively. The reason for the high loss of exergy in the compressors is their low polytropic efficiency. Exergy analysis showed that exergy loss in the main cycle heat exchanger, is 4% higher than that of the pre-cooling cycle heat exchanger, which is due to the higher temperature difference between input and output flows in the main cycle heat exchanger. Analysis of the effect of the size of the heat exchanger, which highly affects investment costs, on the specific power consumption is carried out and the results showed that this effect is minimum at the optimum point and increases proportionally to the distance from the optimum point. Natural gas liquefaction processes require a lot of investment and operation costs and are part of the energy-consuming industries. In this research, parameters such as refrigerant component, inlet and outlet pressure to compressors were optimized in the dual mixed refrigerant system to reduce operating costs. The optimized system was then evaluated by exergy to obtain the amount of exergy loss in various components of the system, finding illustrate the highest exergy losses were in compressors, heat exchangers, aftercoolers and throttle valves, respectively. The reason for the high loss of exergy in the compressors is their low polytropic efficiency. Exergy analysis showed that exergy loss in the main cycle heat exchanger, is 4% higher than that of the pre-cooling cycle heat exchanger, which is due to the higher temperature difference between input and output flows in the main cycle heat exchanger. Analysis of the effect of the size of the heat exchanger, which highly affects investment costs, on the specific power consumption is carried out and the results showed that this effect is minimum at the optimum point and increases proportionally to the distance from the optimum point. https://mej.aut.ac.ir/article_3358_97108695bd93b6be52fa0334874c8722.pdf