Sizing of Scroll and Rolling Piston Compressor for Low-Pressure Refrigerants in Residential Air Conditioning and Heat Pump Systems

Current residential air-condition and heat pump (ACHP) systems mainly use the high-pressure refrigerant R410A with scroll or rolling piston type compressors. With the continuous push on reducing the carbon emission, low-GWP refrigerants with lower pressure and density will be used in ACHP systems to replace R410A soon. Compressors must be resized to achieve similar efficiencies at the matched cooling capacity for low-pressure refrigerants. A physics-based model using geometries and refrigerant properties as input that can predict the compressor performance is desired to provide design guidance on compressor sizing. In this study, the open-source modeling platform (PDSim) based on the mechanistic chamber model is used to study the sizing requirement to match the desired capacity for scroll and rolling piston compressors at standard ANSI/AHRI 210/240 conditions. For each type of compressor, a detailed simulation model is created, validated, and tuned using the experimental data available to ensure accurate prediction on refrigerant mass flow rate, power, and efficiencies. The validated models are then used to run sensitivity study on compressor displacement for R410A, R134a and R1234ze(E), which are selected as representatives for different pressure levels. The needed displacement at different volumetric efficiencies and isentropic efficiencies is reported and compared.