Parametric study and optimization of the precooled Linde-Hampson (PCLH) cycle for six different gases based on energy and exergy analysis

Diverse methods have been proposed for liquefying gases due to their need in different industries. This study examined the precooled Linde-Hampson cycle for liquefying six gases. First, the proposed system is analyzed from a thermodynamic perspective. Then, the effects of pressure ratio on performance parameters such as system required work, heat exchanger-specific heat capacity, number of transfer units, the liquefied gas mass ratio, Coefficient of Performance (COP), and exergy efficiency are examined. The results show that methane at a pressure ratio of 40 has the highest COP (1.606), while argon at a pressure ratio of 220 has the highest exergy efficiency (31.51%). Exergy analysis indicates that the Joule-Thomson valve destroys the most exergy, followed by heat exchanger-3 and compressor-1. Finally, the TOPSIS technique is used as a multi-objective optimization method to optimize the compressor-1 pressure ratio based on two objective functions, COP and exergy efficiency. The results show that in optimal conditions, COP and exergy efficiency are respectively 0.99 and 20.6% for air, 0.93 and 28.35% for argon, 0.97 and 20% for nitrogen, 1.46 and 14.76% for methane, 1.05 and 22.87% for fluorine, and 1.18 and 20.08% for oxygen.