An apparatus for heating and/or cooling a plurality of particles including a generally circular bed for holding the particles, the bed having a substantially centered annular inner bed wall, an outer bed wall and an irregular bottom. The apparatus also includes a drive mechanism rotatably affixed to said bed, where rotation of the drive mechanism at a predetermined rate produces a displacement of the bed horizontally and vertically resulting in a particle flow in the x, y and z directions. The particle flow in the x and y planes for a majority of said particles is in a dominant direction. The apparatus also includes an airplant which provides a heated and/or cooled airflow tangentially into the bed in a direction opposite to the dominant direction.