Abstract: Investigates the application of progressive compression technology in low-temperature air-source heat pump systems. The technical characteristics and optimal operating conditions of progressive compression are analyzed. Based on thermodynamic analysis of an intermediate injection system with an economizer, the compression design is calculated. Under specified working conditions, the optimal intermediate pressure and volumetric ratio (high-pressure cylinder volume to low-pressure cylinder volume) are determined, and the influence of isentropic efficiency on the design parameters is evaluated. Finally, system tests are conducted by controlling the auxiliary expansion valve opening to regulate the injection state. The impact of injection on system performance under different conditions is examined, verifying the trend of system performance with intermediate pressure variation. A comparative analysis of the performance improvement potential between progressive compression with intermediate injection and single-stage compression with intermediate injection under various conditions is presented, providing a reference for future compressor design and selection.

Key words: Progressive compression, Intermediate vapor injection, Optimal intermediate pressure, Volume ratio