Experimental and Numerical Investigation of The Effect of Hydrogel Use on The Performance of a New Fractal Mini-Channel Heat Sinks

Overheating due to the high thermal characteristics of electronic chip products leads to failure and inefficient work. Fractal-shaped water-cooled mini-channels are an innovative geometry used for cooling heat sinks. In the literature, heat distributions in fractal-structured geometries have been investigated by many researchers, both experimentally and numerically. Many researchers have investigated heat distribution in fractal-structured mini-channels, and most of these studies have focused on the overall heat distribution of heat sinks, while only a few have conducted numerical studies on local heat distribution. It is very important to know the local heat distribution in order to provide better performance of the heat sinks. In this study, the thermal effects of conventional Y-shaped mini channels (Y-MC) and temperature-sensitive hydrogel-added Y-shaped mini channels (Y-MCH) were investigated experimentally and numerically. As a result of both experimental and numerical studies, after determining the local temperature zones, it was aimed to obtain a homogeneous heat distribution on the surface by placing temperature-sensitive hydrogel in those zones. Computational fluid dynamics (CFD-FloEFD) software was used in the numerical studies. Poly (N-isopropyl acrylamide) hydrogels have been used as a type of temperature-responsive material that undergoes discontinuous deformation with temperature changes and exhibits rapid response performance. Surface temperature distributions are analysed to evaluate the effects of flow rate and hydrogel incorporation on peak temperature reduction and thermal uniformity. The results show that increasing the flow rate significantly enhances convective heat transfer in both configurations, leading to a reduction in maximum surface temperature. For the hydrogel addition fractal structure, the maximum temperature decreases from approximately 66.6 °C at 50 mlmin-1 to 33.4 °C at 600 mlmin-1, whereas the without-hydrogel configuration exhibits higher temperatures, decreasing from 74.4 °C to 37.1 °C over the same flow rate range. At low flow rates, hydrogel addition reduces the maximum surface temperature by up to 7.8 °C (≈10.5%), with the performance difference gradually diminishing at higher flow rates due to the dominance of forced convection.