A method of crystallizing a plurality of crystallizable polymer pellets includes a step in which the pellets passed through regions that are temperature adjusted by a heat transfer jacket. The heat transfer jacket adjusts the temperature of the pellets by having a temperature sufficient to allow at least partial crystallization of the plurality of polymeric pellets while maintaining the average pellet temperature of the plurality of pellets below the melting temperature of the pellets. A crystallizer implementing the methods of the invention is also provided.