Metal-Foam Skeleton Effects on PCM Thermal Storage for Greenhouse Microclimate Control: A Numerical Study

Abstract

This study investigates passive thermal management strategies for a south-facing greenhouse operating under hot-arid diurnal conditions by integrating phase change materials (PCMs) into the north wall and enhancing their thermal response using open-cell metal foams. A 2D transient CFD microclimate model is developed in ANSYS Fluent. The impact of metal-foam (MF) type is examined by comparing copper, aluminum, and steel foams at 20 PPI and high porosity (ε = 0.93). Results show that inserting MF improves heat spreading inside the PCM modules, leading to smoother temperature fields, reduced local overheating during charging, and more effective latent-heat utilization. Among the tested foams, copper provides the strongest stabilization, typically lowering PCM daytime peak or plateau temperatures by about 5–7 K relative to the nofoam case, followed by aluminum (about 3–5 K) and steel (about 2–3 K). Foam enhancement also accelerates melting, increasing the maximum daily liquid fraction from about 0.22 (no foam) to about 0.35 (copper), 0.33 (aluminum), and 0.29 (steel). The improved thermal coupling modifies buoyancy forcing and airflow patterns, reducing stagnant zones and promoting more uniform circulation. These findings provide material-level guidance for designing MF–PCM storage modules to improve greenhouse temperature buffering with minimal energy input.