The effect of metal foam fins on pool boiling of DI-water

The technology industry's growth has motivated the development of optimized thermal control techniques, such as pool boiling. Different surface designs have been developed to enhance the heat transfer coefficient in different heat transfer applications. These designs aim to improve thermal performance, increase efficiency, and address specific challenges associated with heat exchange. Introducing porous materials or modifying the permeability of surfaces can influence liquid flow patterns and enhance convective heat transfer. Metal foams, for example, have been employed to increase surface area and promote liquid replacement on the surface, enhancing the capillary action and improving heat transfer performance. The current work investigates the effect of different porous microstructured surfaces, based on microchannels and micro-pin fins, on pool boiling heat transfer of deionized water. This work addressed pool boiling tests using copper metal foams fins with different thicknesses, 3 mm and 1 mm, to study the vapor bubble dynamics in the foam cell. The results indicate that porous copper microchannels with a thickness smaller than the capillary length of the working fluid promote vapor bubble departure, thereby enhancing heat transfer (25 % and 21 % for 0.5 and 1 mm of inter-fin-spacing, respectively). The interplay between foam thickness and inter-fin space in porous microchannel surfaces revealed nuanced effects, with smaller inter-fin spaces demonstrating higher enhancement factors at low heat fluxes due to vapor bubble dynamics and capillary effects. In comparison, larger inter-fin spaces showed improved heat transfer coefficients at high heat fluxes by reducing vapor bubble escaping resistance. These findings contribute valuable insights into optimizing pool boiling heat transfer through surface modifications.