Numerical analysis of phase change material melting with partial triangular foam filling: A parametric study of placement and geometry

Phase change materials (PCMs) enable latent heat storage but suffer from poor thermal conductivity. Metal foams improve heat transfer, though research on optimized partial and asymmetric foam fillings remains limited. This numerical study investigates the melting process in rectangular PCM enclosures partially filled with triangular aluminum foam (porosity 0.9), evaluating the effects of foam placement (bottom-left: BL, top-left: TL, top-right: TR, bottom-right: BR), pore density (5–20 Pore Per Inch: PPI), aspect ratio (0.5–2), and inclination angle (−30° to +30°). Using a finite volume method with the enthalpy-porosity technique, the analysis assesses liquid fraction evolution, melting time, temperature uniformity index (TUI), and instantaneous difference between maximum and average temperature (IDMAT). Results reveal that TR and BL placements accelerate melting by aligning with buoyancy-driven convection, reducing total melting time by up to 50% compared to the base case (pure PCM with aluminum block). Higher PPI (up to 20) enhances conduction dominance, shortening melting by 15–25%, while positive inclinations (+30°) improve rates by 10–17% via strengthened flow. Aspect ratios of 2 favor vertically elongated enclosures for sustained convection, decreasing melting time in BL configurations. TUI improves with heater-adjacent foams, and IDMAT minimizes in base and TL cases. The novelty lies in asymmetric triangular foams exploiting natural convection, offering design guidelines for Latent Heat Thermal Energy Storage (LHTES) optimization, balancing heat transfer enhancement and uniformity.