Porous media for advanced hybrid thermal energy storages.

It is well-known that the use of the latent heat absorption phenomenon associated with the melting process of a suitable Phase Change Material (PCM) can be considered an effective way to improve energy storage capabilities in many applications. Among PCMs, paraffin waxes show some desirable features. Unfortunately, they have also two main limitations, a low thermal conductivity and a high volume change during the melting process, that limit their potential applications as PCMs. This work investigates the use of different aluminum porous materials, either stochastic or periodic, as heat transfer medium to mitigate and/or eliminate the two main drawbacks of the paraffin waxes and to improve their overall heat transfer capabilities. In particular, the effects of six open-cell aluminum foams and of a 3-D periodic aluminum structure were experimentally investigated during the phase change process with melting temperatures of 40 °C in a hybrid water thermal storage unit.