A series of experiments are conducted to investigate the non-thermal equilibrium characteristics of melting of a packed bed under horizontal forced and mixed convections. This configuration imposes a complex treatment in phase change heat transfer that involves not only the coupled heat, mass and momentum exchanges but also the local geometric change of the packed bed (packing effect). Using visualization observations and measurements, we determine experimentally the volumes and packing patterns of the melting granular packed beds and the time variation of average melting rate per unit bed volume and average heat transfer coefficient for Re - 71-2291, Gr/Re-2 = 1.48 x 10(-5)-17.32, and Ste = 0.0444-0.385. The effects of water velocity and water temperature on the melting and heat transfer in the melting process are analyzed. The effects of packing patterns on Nusselt number correlations are presented. Using the definition of a terminal velocity, a Reynolds number ratio is developed as the criterion defining the floating, nonfloating or transitional packing pattern. (C) 2003 Elsevier Ltd. All rights reserved.