Numerical analysis of PCM integrated in solar dryers for thermal efficiency

Abstract

Solar dryers using phase change materials buffer heat, yet the combined influence of airflow regime and PCM placement on melting remains underexplored. A controlled like-for-like study fixed geometry and PCM properties while varying placement and operating conditions. A 3D transient CFD model simulated a forced-convection dryer with RT28HC over Re = 3000-9000 and inlet temperatures Ti = 50-60 degrees C. Raising either Re or Ti shortened melt time, and three-wall coverage melted faster and more uniformly than a rear-wall-only layout. For three walls, melt time dropped from 13 h (50 degrees C, Re = 3000) to 7 h (60 degrees C, Re = 9000) (-46 %) for the rear wall it fell from 19 h to 11 h (-42 %). A 10 degrees C increase in Ti reduced overall melt time by 4 h across Re. Practically, three wall PCM with Re >= 6000 at Ti = 60 degrees C achieved reliably 7-9 h melting, enabling late afternoon heat release without auxiliary heating.