Supersonically sprayed, triangular copper lines for pool boiling enhancement

Pool boiling is a mechanism by which heat is removed through nucleation of bubbles at the heated surface. Because of the ever-increasing demand for miniaturization of more powerful electronic devices, heat flux requirements grow. Herein, we introduce a rapid, scalable supersonic spray-coating technique that produces micro-scale lines with triangular cross sections. The surface of each triangular line is textured and provides numerous nucleation sites. Pathways of escaping bubbles experience minimal interference because of the triangular shape of the lines. These rising bubbles remove heat efficiently and facilitate rapid cooling. Both critical heat flux and the effective heat transfer coefficient increased significantly under the optimal coating condition, which is identified. The effect of the number of the patterned lines was studied. The coolant contact angle against the lined surface was investigated to quantify wettability and capillary effects. Bubble formation was visualized with a CCD camera and the triangular-shaped lines were characterized by scanning electron microscopy and an optical profiler.