Climate responsive compressor sizing: effects of displacement volume and refrigerant selection on seasonal performance of rolling piston compressors

This study investigates how compressor displacement volume and refrigerant selection influence the seasonal efficiency of rolling piston compressors in residential air conditioning and heat pump systems. A mechanistic chamber model was developed and validated against experimental data to simulate compressor performance, including friction and leakage losses. To evaluate performance under realistic conditions, two climate zones were analyzed: Rochester, MN (heating-dominant), and El Paso, TX (balanced heating and cooling). Annual building loads for a representative single- family home were generated using EnergyPlus to inform compressor sizing. For each refrigerant location pair, a baseline compressor was designed based on building loads corresponding to the 5th percentile outdoor dry-bulb temperature for heating or the 95th percentile for cooling. These performance-based designs were scaled from 50% to 150% of baseline size and compared with conventional engineering practice, which typically uses more extreme ambient conditions—namely, the 1st and 0.4th percentiles for heating-based design and the 98th, 99th, and 99.6th percentiles for cooling-based design. Results show that optimal sizing is highly dependent on refrigerant and climate. In Rochester, conventional heating-based designs led to over-sizing (126% and 139% of the baseline design size). Optimal SCOPs occurred at 110% size for R410A and R290, and at 70% and 50% for R1234yf and R600a. In El Paso, heating-based design outperformed cooling-based design for R410A, R290, and R1234yf, while R600a favored cooling-based sizing. Conventional cooling-based designs (98th, 99th, and 99.6th percentiles) underestimated the optimal size for all refrigerants except R600a. Overall, the findings highlight that optimal compressor sizing cannot follow a universal rule. Instead, it must account for both refrigerant properties and climate characteristics to ensure high seasonal efficiency, especially when transitioning to low-GWP refrigerants.