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CFD analysis and experimental validation of a stepped early discharge port for over-compression control in a CO₂ scroll compressor.

Author(s) : ZHOU Y., PENG B., LIAO Z., WEI M.

Type of article: IJR article

Summary

Over-compression in transcritical CO₂ scroll compressors leads to considerable energy losses, lower efficiency, and higher thermal loads, thereby compromising both performance and reliability. To address this issue, a novel stepped early discharge port (EDP) is proposed, along with a coupled thermodynamic and geometric design method for determining its location. Using an integrated CFD-experimental approach, the performance of the stepped EDP is evaluated and compared with that of a conventional cylindrical EDP under typical overcompression conditions. Furthermore, its influence on the compressor’s flow field and performance is analyzed across conditions ranging from near-design to severe over-compression pressure ratios. Results indicate that the stepped design yields more stable internal flow and better over-compression mitigation than the cylindrical EDP. Analysis of pressure and mass flow rate at the early discharge port reveals that, compared to the circular EDP, the average early discharge pressure decreases by about 4.2%, while the mass flow rate increases by 41.2%. Moreover, the stepped EDP reduces the peak chamber pressure by 0.22 MPa, significantly exceeding the 0.04 MPa reduction achieved by the cylindrical EDP. The variable-condition study confirms that the overcompression mitigation effect of the stepped EDP is maintained across all investigated conditions, consistently lowering working chamber pressure and promoting a more uniform temperature distribution. Under severe overcompression, volumetric efficiency improves by up to 5.99%, and isentropic efficiency shows a maximum increase of 27.02%. Owing to the optimized flow field structure, leakage mass flow rate decreases by approximately 0.8% under severe over-compression.

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Pages: 13 p.

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Details

  • Original title: CFD analysis and experimental validation of a stepped early discharge port for over-compression control in a CO₂ scroll compressor.
  • Record ID : 30034599
  • Languages: English
  • Subject: Technology
  • Source: International Journal of Refrigeration - Revue Internationale du Froid - vol. 184
  • Publication date: 2026/04
  • DOI: http://dx.doi.org/https://doi.org/10.1016/j.ijrefrig.2026.01.032

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