Heat transfer enhancement in mini-channel using a fibrous porous medium

With the recent miniaturisation of electronic devices, the heat generation density of the devices has increased tremendously, requiring the improvement of the performance of the cooling system. In this study, for the high performance of water cooling devices, we investigated convective heat transfer in a mini-channel where porous media that were manufactured by randomly laminated and sintered fine aluminium wires were inserted as a heat exchanger. We conducted the convective heat transfer experiment by changing the flow state from laminar to turbulent using pure water. We also conducted a numerical analysis using a simple lattice model of porous media with the same wire diameter and porosity as in the experiments by using the software PHOENICS. From both results, we discussed the effect of the structure of the porous media on heat transfer. From the results of the calculated permeability of the porous media using the experimental data of pressure-drop, we confirmed that the flows with the porous media were in a non-Darcy flow state. As heat transfer characteristics, it was shown that the Nu number of the experimental results was larger than that of the computational fluid dynamics (CFD) analysis models. Regarding the effects of wire diameter and porosity, the smaller the wire diameter and porosity, the higher the Nu number. By considering the differences between experimental and analytical results, we proposed two sets of new combination of parameters considering the volume of the fibre of porous media and the surface area, which separately correlated well with relationships of the experimental and analytical results against the Nu number.