# Theoretical and Numerical Research on High-Speed Small Refrigeration Twin-Screw Compressor
###### Abstract  
To investigate the performance of high-speed miniaturized screw refrigeration compressors, this study designed rotors with identical theoretical displacement but varying rated speeds. A normalized analysis established quantitative evaluation criteria for geometric performance, while an exergy analysis model assessed leakage exergy losses. Thermodynamic modeling evaluated the impact of different clearances and rated speeds on performance. Computational fluid dynamics (CFD) simulations analyzed the gas forces and torque acting on the rotors. The rate of efficiency improvement with increasing speed follows a non-linear relationship, demonstrating diminishing returns at ultra-high speeds, where further speed elevation provides negligible efficiency gains. This study reveals that, while tip-housing leakage represents the largest volumetric leakage in screw compressors, interlobe leakage contributes the most significantly to power losses. When the rated speed increases from 3000 rpm to 15,000 rpm, interlobe leakage remains the dominant source of power loss, with its relative contribution showing a marked increase. For compressors with identical cylinder dimensions, reducing the number of lobes decreases the discharge pressure fluctuations and power consumption. Larger wrap angles increase the contact line length and discharge port area, reducing the volumetric efficiency while creating a trade-off between leakage and discharge losses, resulting in an optimal wrap angle that maximizes the adiabatic efficiency. s 2025  
The high-speed operation of screw compressors enables a reduced volume and weight for an equivalent cooling capacity, while significantly decreasing internal leakages through clearances, thereby improving the overall efficiency. The optimal clearance distribution in screw compressors can be determined through thermodynamic modeling, CFD simulations, or experimental validation [3; 4; 5; 6; 7; 8]. [PERSON] et al. [6] demonstrated through a theoretical analysis and experimental studies that the meshing clearance has a substantially greater impact on the performance than the discharge end clearance, with each 0.01 mm increase reducing the volumetric efficiency by 0.4% and 0.13%, respectively. [PERSON] et al. [7] employed a bidirectional coupling approach using ANSYS CFX for fluid dynamics and ANSYS Mechanical for structural analysis to determine variations in the leakage clearance dimensions, enabling accurate performance calculations in their CFD model. By optimizing the compressor's radial clearance to appropriate values, they achieved significant performance improvements, including an 8.2% increase in volumetric efficiency, a 2.5% reduction in indicated power, and a 5.5% enhancement in adiabatic efficiency. [PERSON] et al. [8] experimentally confirmed these clearance effects while noting that an increased rotational speed can mitigate their negative impacts. High rotational speeds in screw compressors generate substantial airflow pulsations and high-frequency noise, as intermittent flow patterns create pressure oscillations that result in structural vibrations and acoustic challenges. These issues can be effectively mitigated through advanced muffler designs or optimized oil supply configurations [9; 10; 11; 12; 13; 14]. [PERSON] et al. [13] conducted comprehensive research on the generation mechanisms and suppression methods for vibration and noise in screw refrigeration compressors, proposing a perforated tube muffler through combined simulation and experimental approaches. This solution achieved an over 60% reduction in the airflow pulsation amplitude, a more than 3 dB (A) noise reduction at the compressor, and an over 8 dB (A) noise reduction in system piping when implemented in actual systems. [PERSON] et al. [14] experimentally investigated oil supply parameter variations in operational compressor units, developing a noise reduction strategy through optimized oil supply configurations while maintaining constant oil flow rates.