Optimizing pool boiling heat transfer with laser-engineered microchannels: Experimental and RSM modeling analysis

This study investigates the Pool Boiling Heat Transfer (PBHT) characteristics of distilled water using modified stainless steel surfaces with laser-processed microchannels. An experimental setup was designed and verified to conduct tests at atmospheric pressure across various heat fluxes ranging from 10 to 150 kW/m² in the nucleate PBHT regime. The microchannel surfaces, which were created using laser technology, had widths between 200 μm and 1000 μm. The experimental results demonstrated a substantial improvement in the Heat Transfer Coefficient (HTC) compared to polished surfaces, with narrow microchannels showing greater enhancement. Specifically, the enhancement ratios of the HTC were 94.3 %, 66.3 %, 44.5 %, 28.5 %, and 21.7 % at microchannel widths of 200, 400, 600, 800, and 1000 μm, respectively, at the highest heat flux. The study employed Response Surface Methodology (RSM) to optimize the PBHT system variables, aiming to achieve an optimal HTC. The quadratic model developed using RSM revealed significant interactions between the variables, with an R² value of 0.9981 for HTC, indicating a high degree of fit. The RSM analysis highlighted that smaller microchannel widths and higher heat fluxes significantly enhance the heat transfer performance, with the model predictions closely aligning with the experimental data. The optimal conditions predicted by RSM were a microchannel width of 217 μm and a heat flux of 146 kW/m², resulting in an HTC of 43.93 kW/m²K and an ΔT of 3.27 °C. This study underscores the effectiveness of RSM in optimizing complex heat transfer processes, offering valuable insights for enhancing PBHT performance through surface modification.