Design and Simulation Analysis of a Helium Centrifugal Cryogenic Compressor for Dilution Refrigerators

The circulation efficiency of Helium within a closed-cycle dilution refrigerator is a critical determinant of the system's cooling power and thermodynamic stability. In conventional architectures, pre-compression is typically achieved using turbomolecular pumps. However, these pumps, inherently designed for high-vacuum molecular flow, impose significant limitations on mass flow rates and are not optimized for cryogenic conditions. There is an urgent demand for substantially greater cooling power to manage increasing heat loads, rendering the limited throughput of current pump technologies a growing bottleneck in system scaling. To address these challenges, this study investigates the feasibility of a centrifugal compressor as a high-throughput alternative. A specialized impeller was developed using a combination of the one-dimensional mean streamline method and three-dimensional Computational Fluid Dynamics simulations, with adopting specific speed as a key design criterion. The design targets the unique thermophysical properties of Helium at cryogenic temperatures and low pressures.The simulation results under design conditions demonstrate that the proposed impeller achieves a mass flow rate of 3.6 g/s and a static pressure ratio of 2.34, significantly exceeding the throughput of traditional solutions. The impeller exhibits excellent aerodynamic performance, achieving an isentropic efficiency of 77.16% and a polytropic efficiency of 81.44%. Furthermore, the study analyzes performance under off-design conditions, establishing a predicted surge line to define the stable operating range. It was observed that at excessive rotational speeds, local supersonic regions develop at the blade leading edge, inducing shock losses that degrade efficiency. These findings confirm that centrifugal compression offers a viable, scalable technical path for next-generation, high-capacity dilution refrigerators.