Experimental study on the temperature control characteristics of graphite foam-based composite phase change materials

Thermal management systems are crucial for ensuring the reliable operation of electronic devices. Heat dissipation using phase change materials (PCMs) is an effective, lightweight method for devices experiencing transient high heat flow. Graphite foam (GF), known for its high thermal conductivity and low density, significantly increases thermal conductivity when combined with PCMs. However, research on the heat transfer characteristics of composite PCMs is limited. This study experimentally investigates the heat dissipation characteristics of a graphite foam-PCM (GF-PCM) composite cooling structure. It explores the impact of factors like the shell's tilt angle, acceleration, and the position of cavities (voids) between the PCM and the shell structure on the transient melting heat transfer of the cooling device under varying thermal source heat flux densities. Results show that using a pure paraffin phase change module, the temperature rise of the heat source increases with the tilt angle, and horizontal placement offers the best heat dissipation and temperature control. The position of the cavity influences heat dissipation; at 30W heating power, a cavity between the heat source and paraffin increases the temperature rise of the heat source by 19.2 %. Furthermore, cavity position is affected by acceleration; at 50W heating power and 3.6g acceleration, the cavity shifts from the top of the module to near the heat source side, increasing its final temperature by 3.7 °C. Acceleration also enhances liquid paraffin convection, significantly affecting paraffin's later melting stage. Adding graphite foam speeds up paraffin melting, reducing the temperature rise of the heat source by 42.8 %, 42.9 %, and 28.3 % at 30W, 40W, and 50W heating powers, respectively. This improvement mitigates the adverse effects of tilt angle, cavities, and uncertainties introduced by acceleration.