Effect of Metal Foam Filling Position and Porosity on Heat Transfer of PCM: A Visualized Experimental Study

The application of phase change material (PCM) in energy storage systems is limited by its low thermal conductivity. One of the effective methods to improve the thermal conductivity of PCM is to embed foam metal within it. To investigate the effects of foam metal infill position and porosity on the melting process and temperature distribution of PCM, a visualized experimental system study is built. Paraffin is employed as the PCM with a melting point of 62°C, while 85%, 90%, and 95% porosity copper foam are chosen in the experiment. The evolution of the liquid-solid phase interface and the temperature distribution in the PCM are recorded. Single-layer filling schemes show that placing copper foam closer to the bottom accelerates melting, while double-layer schemes further optimize the melting time and temperature distribution. Additionally, decreasing the porosity of copper foam enhances heat transfer, shortening melting times. The study introduces a melt efficiency index, demonstrating that optimizing filling schemes and porosities improves the overall melting performance. When the copper foam with 90% and 85% porosity is arranged in the middle and bottom layer, respectively, the complete melting time is shortened by 38.2% and the maximum and average temperature differences are reduced by 30.0% and 45.2%, respectively, compared with pure paraffin. The findings contribute valuable insights into designing efficient PCM systems for thermal energy storage applications, emphasizing the importance of copper foam arrangement and porosity optimization.