Heat transfer characteristics in subcooled flow boiling with hypervapotron

An experimental study of subcooled boiling heat transfer was conducted using R-134a in compact hypervapotron structures. The investigated flow and condition parameters in R-134a were: (1) inlet pressure of 5–8 bar, (2) mass flux of 186–310 kg/m2 s, (3) subcooling temperature of 10–30 °C. Two distinctive zones were identified in the boiling process of the hypervapotron. It was found that the fully developed boiling curve has a slope range of 2.1–3.0 under tested conditions, which shows good agreement with Bjorge’s observations for flat surface channels. Shah and Kandlikar’s correlations are utilized to predict the heat transfer coefficient for fully developed boiling regions and some important parameters are suggested for hypervapotron applications based on the experimental results.