US Patent 10209009 Heat exchanger including passageways

A heat exchanger includes a core defining a first passageway and a second passageway. The core includes a plurality of unit cells coupled together. Each unit cell of the plurality of unit cells includes a first wall and a second wall. The second wall is spaced from the first wall. The first wall at least partially defines a first passageway portion and a second passageway portion. The second wall at least partially defines the second passageway portion. The second wall extends about the first wall such that the first passageway portion is nested within the second passageway portion.