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Urea prills are produced in a prilling tower where a cooling-solidication process takes place. The ambient air is used as the cooling air stream for this process. In this study, the cooling-solidication process was numerically investigated in the particle size range of commercial product. The simulations predicted that the temperature of smaller particles fully solidifed became nearly identical with that of cooling air over the entire body at the bottom of tower. It was found, on the other hand, that the temperature of larger particles remained high over a large portion of its core part. SEM observation of the particle cross-section favorably validated the numerical predictions.