Study on the flow boiling of different media under supercooled conditions on surfaces with microstructures

Previous studies have demonstrated that altering the surface structure can enhance heat transfer. In this study, a square micropillar array with a homogeneous structure was designed for a long rectangular channel with a hydrodynamic diameter of 10 mm. Deionized water and HFE-7100 were used as working fluids for the study. The effect of flow rate and subcooling degree on flow boiling heat transfer performance is discussed. The bubble behavior of two different media was compared by visualization experiments. The results show that the square microcolumn array will delay the ONB point by increasing the heat transfer area and disturbing the main fluid, and improve the overall boiling heat transfer performance by 2–3 times. It was found that HFE-7100 boils better under low heat flow density, but its stable nuclear boiling time is shorter. Furthermore, the effects of volume flow and subcooling on heat transfer performance vary significantly at different stages of the boiling process. Before the ONB point, an increase in volume flow will increase the heat current density by 88.9% and reduce the boiling heat transfer stability. After the ONB point, the effect of fluid flow on the boiling process weakens.