# Theoretical and Numerical Research on High-Speed Small Refrigeration Twin-Screw Compressor
## 6 Conclusions  
This study investigated the high-speed miniaturization potential of refrigeration screw compressors by designing rotors with varying rated speeds at constant displacement. A comprehensive analysis framework was developed, integrating geometric characterization, thermodynamic modeling, and CFD-based force analysis. The performance characteristics under miniaturized high-speed conditions were systematically compared, leading to the following conclusions.  
At constant rated speeds, reducing the leakage clearances significantly improves both the volumetric and adiabatic efficiencies. As the rated speed increases and the rotor dimensions decrease, the gas forces acting on the rotors decrease significantly, generally correlating with the reduction in the force-bearing areas. However, the gate rotor experiences higher-than-ideal axial and end-face gas forces. Under ultra-high-speed conditions, the efficiency gains from further speed increases become negligible.  
While tooth tip leakage represents the largest volumetric leakage flow in screw compressors, contact line leakage contributes the most significantly to the power losses due to the huge pressure differential across the contact line. When the rated speed increases to 15,000 rpm, contact line leakage remains the dominant source of power loss, with its relative contribution showing a marked increase.  
For screw compressors with identical cylinder dimensions, reducing the number of lobes increases the area utilization coefficient while enabling leakage reduction through optimized profile design. Larger wrap angles, at constant theoretical displacement and rotor profiles, extend the contact line length and increase the discharge port area, leading to reduced volumetric efficiency. This creates a trade-off between increased leakage losses and decreased discharge losses, resulting in an optimal wrap angle that maximizes the adiabatic efficiency.  
This research on high-speed small screw compressors is a comprehensive study. However, this article only theoretically considers the influence of the structural parameters of high-speed miniaturized rotors on their performance. In addition to theoretical design, the selection of high-temperature-resistant and high-strength materials for rotors, rotor dynamic balance and thermal deformation, aerodynamic noise caused by high speeds, cooling, and lubrication are all directions for subsequent research.  
Conceptualization, X.W. and Z.H.; methodology, K.M. and D.L.; software, K.M.; validation, K.M. and X.W.; formal analysis, H.L.; investigation, H.L.; resources, X.W.; data curation, K.M.; writing--original draft preparation, K.M.; writing--review and editing, K.M.; visualization, K.M.; supervision, H.L. and Z.H.; project administration, Z.H.; funding acquisition, X.W. and H.L. All authors have read and agreed to the published version of the manuscript.  
The project was supported by the National Key Research and Development Program of China (Project No. 2024 YFB4007403).  
Not applicable.  
The original contributions presented in the study are included in the article, further inquiries can be directed to the corresponding author.  
Authors [PERSON] and [PERSON] were employed by the company Gree Electric Appliances Inc. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.