CONCEPTUALIZATION, THERMAL ANALYSIS, AND MANUFACTURING OF NANO-TEXTURED MICRO-STRUCTURED SURFACES FOR ENHANCED CONDENSATION HEAT TRANSFER

In the present study, nano-micro-structured surfaces have been systematically designed and manufactured in order to generate controlled dropwise condensation mode for enhanced heat transfer during phase-change from vapor liquid. The conceptualization of micro-structures was conducted by using thermal modelling an individ-ual droplet pinned at a single micro-hexagonal cavity. By varying radius, resulting contact angles geo-metric dimensions micro-structure, threshold values determined later manufacturing process. According calculations instance 150°, subcooling 1 K maximum radius 100 µm, edge length depth should be kept below 50 µm 25 respectively. Ensuring these parameters, roughly % larger coefficient would result compared that predicted classical Nusselt theory filmwise condensation. Taking into account mathematical analysis, laser ablation technique adopted on 7075 aluminum samples emboss hexagonal structures with respect dimensions. After this step, were electrochemically etched achieve more than 150° ensure superhydrophobic solid-liquid interaction surface. Measurements high-precision microscope show most structure geometric shape precisely manufactured. Tensiometer results disclosed surface topography all exhibit sessile individual micro-hexagon.