A fractal blade for cooling liquids: Experiments and simulations

The performance of a fractal geometry blade for cooling hot water by natural convection and evaporation was studied numerically and experimentally. The blade design includes a tree-like fractal pattern and the Sierpinski carpet. The fin is made up of a solid hollow structure whose core is embedded with a porous material through which liquid flows. For the experiments, temperature measurements were taken in the porous medium by holding the fin in a fixed vertical position while warmed water was fed through its flow inlet. Numerical simulations were performed using a two iteration scheme that first involves the calculation of the local convective heat transfer coefficients and then the estimation of the heat dissipated by evaporation. The behavior of the fractal blade was compared with that of a benchmark heat sink that does not include the Sierpinski pattern in its construction. The experimental and numerical results agree well with each other and show a better performance of the reference heat sink when cooling water. Although the windows in the Sierpinski pattern improve convective cooling, this effect is marginal compared to evaporative cooling, which is enhanced by the larger surface area of wet porous medium exposed to the environment in the benchmark fin.