A review of axial force balance and clearance sealing techniques for energy-efficient scroll compressors

Developing next-generation scroll compressors with higher efficiency and reliability is crucial for promoting energy conservation and emission reduction. Among the key technical challenges encountered, radial gas leakage remains a predominant issue that can severely impair both operating performance and energy consumption. This paper begins by elucidating the flow characteristics and estimation methods for radial leakage. The influence mechanisms for radial leakage and the performance effects are then examined in terms of leakage rate, power consumption and scroll surface wear. The unsteady characteristics of axial gas force, which pose a primary challenge to axial clearance sealing, are analyzed through a combination of theoretical analysis, CFD simulation and experimental measurement. Based on this foundation, this paper provides a comprehensive review of key advancements in axial force balance and clearance sealing techniques, including conventional approaches such as gas back-pressure, oil back-pressure, axial compliance and passive aerodynamic sealing mechanisms as well as emerging solutions like passive magnet and active electromagnet mechanisms, with a focus on their principles, topology, effectiveness, and limitations. Finally, the study highlights key insights and unresolved challenges, recommending hybrid electromagnetic mechanisms as a promising solution that combines the advantages of both passive and active dynamic force balancing techniques.