Laser texturing of silicon surface to enhance nucleate pool boiling heat transfer

Abstract

• The laser texturing technique is used to modify the silicon-based heat exchange surface. • Modified surface is characterized by superhydrophilic properties and high stability. • The laser-textured surface demonstrates the heat transfer enhancement during water pool boiling. • The surface modification leads to the considerable change in the dynamics of vapor bubbles. The surface modification is one of the most promising and discussed methods to improve the boiling performance. To date there are a lot of techniques to modify a heating surface, but the search for the optimal, simple and reliable one is still an actual problem. Recently, the surface texturing using laser ablation was applied in a number of studies, which showed its great potential for heat transfer enhancement and critical heat fluxes increase during pool boiling on the metal surfaces. In this paper, we modified a silicon surface by laser texturing and analyzed its effect on the heat transfer and bubble dynamics during water pool boiling using high-speed thermography and video recording. The experiments showed that the usage of laser-textured surface results in the heat transfer enhancement up to 49.5% compared to the reference rough silicon sample and up to 234% compared to the polished sample. Moreover, the modified surface is characterized with lower onset of nucleate boiling and lower bubble nucleation temperature. Dataset on the major characteristics of bubbles dynamics during boiling on the untreated and laser-textured surfaces was obtained using the high-speed video recording. Its analysis showed that the laser treatment leads to the significant increase in the nucleation site density and nucleation frequency, while the bubble departure diameter value dramatically decreases compared to the reference surface. On the basis of experimental data the relationship between nucleation frequency and departure diameter was found and analyzed both for untreated surface and for laser-textured one.