Thermoeconomic Assessment of Linde–Hampson Cycle Configurations for Methane Liquefaction

Reducing the compression work of a liquefaction cycle does not necessarily reduce the irreversibility generated within its components. This study examines this distinction in three Linde–Hampson configurations for methane liquefaction, analyzed from an energy, exergy, and exergoeconomic perspective: ideal isothermal, single-stage real, and two-stage real compression with intercooling. A regenerative heat exchanger effectiveness of 0.95 is assumed, so the return stream reaches the make-up gas junction below the reference temperature, where its remaining exergy is destroyed in a non-adiabatic mixer. The model reproduces literature results within 1% in the liquefied fraction. The three configurations share the same refrigeration effect and liquefaction fraction, 180.874 kJ/kgTG and 0.181, so the differences arise in the compression system. Intercooling lowers the specific energy consumption by 23.9% and the maximum compression temperature by 34.4%, yet increases the internal irreversibility from 3923.251 to 4035.156 kW. The benefit of intercooling becomes apparent when the residue exergy and the total irreversibility are considered together. The residue exergy falls by 50.1%, while the total irreversibility decreases from 8912.031 to 6524.151 kW. The exergoeconomic costs of the product and residues decrease by 21.88% and 61.20%, respectively. The residues cost 4.5 times as much as the liquefied methane in single-stage compression and 2.2 times as much in two-stage compression, so tracing the formation of those costs provides the basis for identifying the better configuration.