A novel optimum design method and performance analysis of cryogenic hydrogen turbo-expander for hydrogen liquefaction

Abstract

Large-scale hydrogen liquefaction predominantly employs the Claude cycle, incorporating a hydrogen turbo-expander for isentropic expansion to substantially reduce energy consumption. However, existing simulations often assume arbitrary turbo-expander efficiencies without considering practical feasibility under varying conditions. The evaluation and optimization of the hydrogen turbo-expander’s performance remain insufficiently explored in current studies. This research introduces a novel optimization methodology for the preliminary design of hydrogen turbo-expanders by integrating the traditional mean-line method with Particle Swarm Optimization (PSO). This is the first application of such an integration specifically for hydrogen turbo-expanders, addressing the unique challenges of hydrogen liquefaction. The optimized design achieves a 3.82 % increase in efficiency over conventional mean-line approaches. Moreover, this research develops a comprehensive procedure for analyzing hydrogen turbo-expander performance, investigating efficiency changes across various design parameters and operating conditions. We develop efficiency maps tailored to hydrogen’s real gas properties, employing dimensionless parameters to illustrate how design and operating conditions such as flow coefficient ϕ, loading coefficient ψ, specific speed Ns, volumetric expansion ratio VR, and turbine size SP impact efficiency. The optimized preliminary design method eliminates subjective efficiency assumptions in liquefaction simulations, provides reliable efficiency values, and reduces the computational resources and time required for subsequent detailed design procedures.