Nanoparticles-induced heterogeneous condensation and geometry optimizations to enhance liquefaction efficiency and mitigate exergy loss in a novel hydrogen liquefaction two-phase expander

Hydrogen liquefaction methods primarily rely on various refrigeration cycles and nanoparticles are integrated into process to enhance the liquid hydrogen production yield by modifying material properties. Besides, the nanoparticles can induce the heterogeneous condensation in a novel hydrogen liquefaction transonic two-phase expander(TTPE). The TTPE is modeled as a De Laval nozzle for simplification and numerical technology is applied to improve the efficiency and minimize the exergy loss of hydrogen liquefaction by focusing on non-equilibrium condensation. For the first time, a mathematical model is established for a heterogeneous non-equilibrium condensing flow with hydrogen liquefaction incorporating the effect of nanoparticle. By introducing nanoparticles with boundary conditions set at a concentration of 10181/kg and a 10 nm radius, the efficiency of hydrogen liquefaction can be maximally enhanced by 4.29 %. Additional, by optimizing the geometrical structure of the de Laval nozzle, efficiency is improved by 2.93 % and 9.30 %, respectively, with further potential enhancements. Detailed analyses for TTPE are conducted of hydrogen liquefaction flow losses, thermal efficiency and total exergy loss under different flow conditions. Precise control of nanoparticle concentration and size, along with the regulation of intake compression and expansion state are necessary to enhance the feasibility of the liquefaction process. Finally, we discuss future research directions aimed at comprehensively enhancing the liquid hydrogen yield and reducing total energy consumption losses through effective and achievable strategies.