The effect of pressure on heat transfer at evaporation/boiling in horizontal liquid layers of various heights on a microstructured surface produced by 3D laser printing

摘要

Heat transfer was experimentally studied under evaporation/boiling conditions in thin horizontal layers of n-dodecane at low relative pressures. A capillary-porous coating from a stainless steel powder with a sinusoidal 2D modulated profile was applied using a 3D laser printer. The selective laser sintering (SLS) additive technique was applied in the study. The dependence of a heat transfer coefficient on the heat flux under different pressures was studied for liquid layers various heights. The resulting experimental data were compared with the values obtained during evaporation/boiling on a smooth surface under the same conditions. A rise in the relative pressure results in an increase of the heat transfer coefficient at bubble boiling. The study demonstrates that the use of a capillary-porous coating leads to a 3.5-fold increase of the heat transfer coefficient in the regimes of bubble boiling. The heat transfer coefficient on the capillary-porous coating was lower compared to a smooth surface in heat transfer regimes with evaporation at low relative pressures. The critical heat fluxes (CHF) on the capillary-porous coating increase with the increasing height of the liquid layer.