Experimental study on heat transfer characteristics between spherical solid particles and cylindrical surfaces

This study experimentally investigates heat transfer between corundum particles (1-3 mm) and cylindrical surfaces. Results show that reducing particle diameter from 3 mm to 1 mm increases the heat transfer coefficient by 50–100 W·m -2 ·K -1 . A 100°C rise in wall temperature enhances the coefficient by ∼26 W·m -2 ·K -1 . Critical relative motion velocities ( V cr ) are identified as 0.09 m/s (1 mm), 0.06 m/s (2 mm), and 0.03 m/s (3 mm). Below V cr velocity boosts coefficients by up to 35%, while effects diminish above V cr (<5% variation). Two dimensionless correlations are proposed: (82.4% data within ±20% error for V > V cr ) and (94% accuracy for V < V cr ), providing reliable tools for industrial waste heat recovery design.