Experimental Assessment of the Moving Magnet Linear Compressor in a Vapor Compression Refrigeration System Using R134a

Vapor compression refrigeration systems account for substantial global electricity consumption, and improving compressor efficiency offers significant potential for energy conservation and climate change mitigation. Linear compressor technology, particularly moving magnet configurations, has attracted attention for its oil-free operation and reduced friction losses, yet comprehensive experimental data under realistic refrigeration cycle conditions remain limited. This study experimentally evaluates the operational characteristics and performance of a moving magnet linear compressor integrated into a complete R134a vapor compression refrigeration system. The investigation systematically varies compressor load from 65% to 85% and pressure ratio from 2.0 to 3.5 while maintaining a fixed condenser temperature of 45 °C. Key parameters, including resonant frequency, piston offset, matching capacitance, power input, mass flow rate, motor and volumetric efficiencies, refrigerant mass distribution, cooling capacity, and coefficient of performance (COP) were measured and analyzed. Results indicate that piston offset remains nearly constant under varying compressor loads, fluctuating around 0.39 mm, but increases by 36% as pressure ratio rises from 2.0 to 3.5, necessitating careful pressure ratio control to prevent mechanical interference. Motor efficiency decreases from 87.7% to 82.4% as the compressor load increases, suggesting favorable part-load operation for domestic energy consumption reduction. This potential remains to be verified through long-term cyclic tests and a full annual energy assessment. The condenser consistently stores over 70% of the refrigerant charge, with distribution most sensitive to operating condition changes. Cooling capacity reaches a maximum of 434.6 W at 85% load and a pressure ratio of 2.0, while the COP achieves approximately 4.5 under the same conditions and decreases to 2.4 at a pressure ratio of 3.5. Normalized COP remains relatively stable at approximately 0.33 across the tested conditions. These experimental findings provide a robust baseline for the design, integration, and control of moving magnet linear compressors in energy-efficient refrigeration applications.