Experimental investigation of PCM melting with graphite/aluminum alloy "sandwich" plate of high thermal conductivity

This work proposed the "sandwich" structure of the graphite/aluminum alloy high thermal conductivity plate. The study is focused on the heat dissipation effect of graphite/aluminum alloy "sandwich" plate (GASP) in the phase change heat storage heat sink. Firstly, the equivalent thermal conductivity of the GASP was measured experimentally. Then melting experiments were performed with heating powers of 15 W, 20 W, and 30 W in the cavity with pure paraffin, aluminum alloy plate, and GASP. Phase and temperature field visualization are observed by the digital camera and infrared thermal imager combined with thermocouples at the vertical-mid plane inside the cavity, respectively. Visualized images revealed that the existence of the GASP dominates the melting direction of the paraffin perpendicular to the plate and shortens the melting distance of the paraffin. Melt fractions, absorbed energy, and Nusselt numbers can be obtained from experimental data based on the melting process. Furthermore, the melting enhancement ratio was defined and thermal control performance was investigated. Experiment results indicated that adding GASP increased the melting rate and decreased the melting time. The melting enhancement ratio decreased with raising the heating power which indicates GASP is more effective at lower heat flux. Meanwhile, the positive optimization of increasing heat transfer area on melting exceeds the negative effect of decreased Nusselt number.