Visualization and Modeling of Flow Boiling of R-134A in Minichannels with Transverse Ribs

This research was undertaken to investigate the flow boiling of R-134a in minichannels with transverse ribs. The test channel consisted of two parallel plates; the lower plate was heated, and the upper plate was adiabatic. A number of transverse ribs were deployed along the lower plate. The hydraulic diameter of the channel was 1.93 mm. In these experiments, the main test parameters were mass flux, saturation temperature, heat flux, and average vapor quality. With these parameters, the convective and boiling numbers ranged from 0.04 to 0.90 and 7.49 × 10^{? 4} to 8.98 × 10^{? 4} , respectively. Of a total of 60 data points recorded, 78% of the data fell in the convective boiling region, while the remaining 22% were in the nucleate boiling region. A two-equation model was fit to a total of 60 experimental data, resulting in a correlation that predicted 58 data points to within ± 10%.