An Investigation of Void Fraction for Low GWP Refrigerants

Abstract

An experimental facility was designed and fabricated to test the void fraction of fluids. Measurements of the void fraction for R134a, R290, and R1234yf were conducted for low mass flux conditions at air-conditioning evaporator temperatures. Test sections of round tube inner diameters 2.99 and 4.56 mm were tested. Flow visualization was performed on the 4.56 mm test section. Results of the flow visualization revealed similar flow regime transition characteristics among the three refrigerants. Void fraction trends for R134a and R290 were found to be similar, while the void fraction for R1234yf trended higher than R134a for most points. The experimental data was compared to predictions by twelve void fraction correlations. For R134a and R290, the Steiner correlation most accurately predicted the data. For R1234yf, the Baroczy correlation was found to most accurately predict the data.