Abstract: A heat exchanger for a sealed enclosure is disclosed that includes a separator plate and a motor secured to the separator plate. The motor rotates a shaft having opposed ends, an ambient air impeller is secured to one end of the shaft, and an enclosed air impeller is secured to an opposite end of the shaft. An ambient shell secured to the separator plate substantially encloses the ambient air impeller and an enclosed air shell secured to the separator plate substantially encloses the enclosed air impeller. Each shell has an axial opening and a radial opening and a plurality of curvilinear fins extending between the separator plate and the shells. Airflow through the enclosed air shell imparts heat to the fins which transfer the heat for rejection by the airflow through the ambient air shell.