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The isothermal phase transition process of pure working fluids cannot effectively match the liquefied natural gas (LNG) gasification process, resulting in low efficiency of LNG cold energy power generation systems. In order to improve the temperature matching characteristics, mixed working fluids with a temperature glide during the phase change process can be adopted. In our previous study, the two-stage condensing process also effectively improved the temperature matching characteristics; thus, this paper presents a two-stage condensation combined cycle using zeotropic mixtures, and the effects of the type and number of components for mixed refrigerants on the two-stage condensing combined cycle system performance are studied. With the net power output as the objective function, the evaporation temperature, condensing temperatures, LNG expander inlet temperature, and working fluid mole fractions are optimised by the genetic algorithm. The results demonstrate that the net power output of n-C 5 H 12 is the largest among the studied pure fluids. The net power output of the binary mixed working fluid at the optimum mole fractions is obviously superior to that of pure working fluids. The system performance is improved when the hydrocarbon mixture is selected as a working fluid, and the optimum number of components is three. [ABSTRACT FROM AUTHOR]

The vanadium-based amorphous electrode material can realize the valence state conversion and increase its specific capacity through the multi-electron reaction. We have obtained V 2 O 5 –Li 3 PO 4 glass with a strong reducing agent CaC 2 , realizing a multi-electron reaction of V5+ to V4+ and then to V3+ in the model system. Moreover, we have explored the relationship between valence state, crystallinity, and conductivity limit to compare the cycle performances of amorphous glass batteries. The CaC 2 content of 20%, V4+ presented the dominating valence state with a content of 77.5%. VP-C20% exhibited a maximum specific capacity of 319.3 mAh g−1, and the specific capacity after 100 cycles was 280.3 mAh g−1, corresponding to a retention capacity of 87.8%. The electrochemical performance of amorphous vanadium oxide decreased with the increase of the LiV 2 O 5 's nanocrystallinity. Crystallinity and the controllable multi-electron reaction could provide an important reference for designing other new electrode materials with high capacity and long cycle life. Image 1 • Vanadium-based amorphous electrode material could realize valence state conversion. • V5+ was reduced to V4+, then to V3+ with CaC 2 , as reducing agent. • V4+ enhanced ion and electron transport and cycling stability. • The performance decreased with the increase of LiV 2 O 5 's nanocrystallinity. [ABSTRACT FROM AUTHOR]