Thermodynamic analysis of linear compressor using R1234yf

Abstract

Without crank mechanism, linear compressors can provide significant advantages such as selection of refrigerants, miniaturization, high efficiency, and non-start/stop. Free motion of piston means that displacement can be modulated according to heat load and friction loss of refrigerants. R1234yf is a synthetic refrigerant with global warming potential (GWP) of only 4 which is considered as an ideal replacement for R134a for automobile air conditioner and domestic refrigerator. In this paper, both modelling and measurements were conducted to study the thermodynamic performance of linear compressor using R1234yf in terms of P–V loop, polytropic index, motor efficiency, piston offset, mass flow rate, cooling capacity and coefficient of performance (CoP). The results from the simplified model agree well with measurements. For a pressure ratio of 2.5, a stroke of 12 mm with a condenser temperature of 40 °C, the linear compressor using R1234yf can achieve a motor efficiency of 86%, a cooling capacity of 120 W and a CoP of 3.0. The thermodynamic efficiency of R1234yf is 20–50% lower than R134a. The simplified model is capable of evaluating linear compressor performance with refrigerants.