Experimental Investigation on Latent Thermal Energy Storages (LTESs) Based on Pure and Copper-Foam-Loaded PCMs

In this work, a commercial paraffin PCM (RT35) characterized by a change range of the solid-liquid phase transition temperature Ts−l=29–36 °C and the low thermal conductivity λSL=0.2 W/m K is experimentally tested by submitting it to thermal charging/discharging cycles. The paraffin is contained in a case with a rectangular base and heated from the top due to electrical resistance. The aim of this research is to show the benefits that a 95% porous copper metal foam (pore density PD=20PPI) can bring to a PCM-based thermal storage system by simply loading it, due to the consequent increase in the effective thermal conductivity of the medium (λLOAD=7.03 W/m K). The experimental results highlight the positive effects of the copper foam presence, such as the heat conduction improvement throughout the system, and a significant reduction in time for the complete melting of the PCM. In addition, the experimental data highlight that in the copper-foam-loaded PCM the maximum temperature reached during the heating process is lower than 20K with respect to the test with pure PCM, imposing the same heat flux on the top (P=3.5 W/m2).