Nucleate pool boiling heat transfer on etched and laser structured silicon surfaces

Pool boiling experiments were performed using saturated double-distilled and degassed water on 10 x 10 mm silicon samples, which were (i) untreated; (ii) laser structured; or (iii) modified with etched artificial nucleation cavities. The etched silicon surfaces were fabricated with differently sized micro nucleation cavities (5-30 mu m) and pitches (0.125-2 mm) to allow a comparative analysis of the fabricated surfaces. The heat transfer coefficient (HTC) comparative analysis conducted at the heat flux of 200 kW/m(2) exhibits the highest enhancement of 244% during nucleate boiling on the silicon sample with etched nucleation cavities with a 30 mu m diameter and a 0.125 mm pitch. The experimental results consistently show that HTC increases with decreasing the pitch and increasing the size of the nucleation cavities in the range of the experimental conditions. The superheat required for the onset of nucleate boiling and the critical heat flux were not substantially affected with the structured surfaces. However, the boiling phenomena propagates more promptly to the entire available silicon surface, when the sample is laser treated or etched compared to the reference bare silicon sample. (C) 2019 Elsevier Ltd. All rights reserved.