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Performance enhancement of cryogenic nitrogen ejectors for HEPS: a model-data dual-driven approach.

Author(s) : WANG Y. Q., DING R., ZHANG J. R., GE R., MA C. C., HUO Y.

Type of article: IJR article

Summary

The maintenance of systems in large-scale scientific facilities and major engineering projects is critical. However, the design optimization of key components is often constrained by prohibitive computational costs and complex multi-objective trade-offs, limiting performance improvements. Focusing on cryogenic nitrogen ejectors in the gaseous nitrogen return lines of cryogenic cooling systems at beamline stations of High Energy Photon Source (HEPS), a key scientific bottleneck was addressed in this work. The bottleneck involved the high computational cost of three-dimensional Computational Fluid Dynamics (CFD) simulations and the presence of conflicting optimization objectives. To resolve this, an innovative integrated framework that combined CFD simulation, surrogate modeling, and multi-objective optimization was proposed. Key geometric parameters, including the nozzle throat radius, mixing chamber radius, and diffuser angle, were first identified through Plackett-Burman screening. A hybrid surrogate modeling approach utilizing Kriging and Deep Neural Networks (DNN) was then employed to accurately and rapidly predict performance metrics such as the Entrainment Ratio (ER) and outlet mean temperature T. Subsequently, multi-objective optimization was conducted using the Non-dominated Sorting Genetic Algorithm II (NSGA-II), Multi-Objective Particle Swarm Optimization (MOPSO), and ParEGOstyle Bayesian optimization (ParEGO-BO) algorithms. Distinct from traditional designs that focus solely on pressure recovery, this study selected ER, T, and outlet mass flow rate mo˙ut as the key performance indicators to ensure both energy efficiency and the thermal-hydraulic balance of the cryogenic loop. The results demonstrated that the optimized geometry achieved a 75.2% increase in ER compared to the baseline design. Furthermore, the optimization successfully constrained T and mo˙ut within the rigorous operational margins required by HEPS, validating the feasibility of the proposed method for large-scale scientific facilities. Main findings and results of this work can provide a passive pulsation-damping solution for the HEPS nitrogen return line that ensures thermal-hydraulic compatibility.

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Pages: 14 p.

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Details

  • Original title: Performance enhancement of cryogenic nitrogen ejectors for HEPS: a model-data dual-driven approach.
  • Record ID : 30034911
  • Languages: English
  • Subject: Technology
  • Source: International Journal of Refrigeration - Revue Internationale du Froid - vol. 186
  • Publication date: 2026/06
  • DOI: http://dx.doi.org/https://doi.org/10.1016/j.ijrefrig.2026.106893

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