Exergy, exergoeconomic and exergoenvironmental assessments and optimization of a novel solar cascade organic Rankine cycle assisted hydrogen liquefaction cycle

Abstract

In this research, a combined cascade organic Rankine cycle (CORC) and ejector refrigeration loops incorporated with the concentrating linear Fresnel solar collector (LFSC) is proposed as a pre-cooling section to reduce electricity work consumption in a mixed refrigerant (MR) hydrogen liquefaction process. The exergy, exergoeconomic and exergoenvironmental analyses of the system during a year and special days are conducted in detail. Moreover, the annual thermodynamic, economic and environmental impact (EI) performances of the proposed system are evaluated by varying the substantial design parameters. Parametric study indicates that increasing the back pressure of turbine in the low temperature (LT) loop improves all aforementioned performances of the system. Meanwhile, bi-objective optimization based on non-dominated sorting genetic algorithm (NSGA-II) and LINMAP, TOPSIS and Shannon entropy decision makers are used to ascertain the optimum COPEx and economic/EI factors of the system concerned. Referring to the results, COPEx is improved by 10% and the cost and EI per exergy unit of LH2 reduce to 0.0309 $/MJ and 1.361 Pts/MJ through TOPSIS method.