The present invention relates to a heat exchanger comprising: a core having a plurality of concentric channels extending along a central axis, the plurality of channels being concentric about the central axis and including: a first set of concentric channels through which a first fluid can pass; and a second set of concentric channels through which a second fluid can pass, to exchange heat with the first fluid passing through the first set of concentric channels, the concentric channels being alternatingly arranged, from the central axis, between a channel of the first set of concentric channels and a channel of the second set of concentric channels.