Flow boiling heat transfer performances of R1234ze(E)/R152a in a horizontal micro-fin tube

The boiling heat-transfer performances of R1234ze(E)/R152a (0.4/0.6 by mass) flowing inside a horizontal micro-fin tube of 9.52 mm outer diameter were researched by experiment. Under the experimental conditions of mean vapor quality between 0.02 and 0.98 with the mass flux of 50 ~ 100 kg/(m2·s), saturation temperature from 12 to18°C and heat flux from 5 to 20 kW/m2, and the impacts of mass flux, heat flux, saturation temperature, and mean vapor quality on flow boiling heat-transfer coefficient (HTC) and frictional pressure drop were mainly investigated; furthermore, the impact of mass transfer resistance on flow boiling process was discussed. The results indicate that R1234ze(E)/R152a obviously reveals the dry-out phenomenon in the flow boiling process, the boiling HTCs increase as the saturation temperature and heat flux, decrease and then increase as the mass flux; the frictional pressure drop rises as the mass flux and declines as the saturation temperature, while the frictional pressure drop is scarcely affected by the heat flux; it is also found that the boiling HTCs take on a decreased trend whole within the entire range of mean vapor quality, which implies that the mass transfer resistance brings about the heat-transfer degradation during the flow boiling process.