A heat exchanger comprising: a first fluid circuit formed by: a first set of fins that extend radially and that are coaxial with each other; a first inlet header fluidly connected to and disposed on an upstream end of the first set of fins, wherein the first inlet header comprises a circular shape; and a first outlet header fluidly connected to and disposed on a downstream end of the first set of fins, wherein the first outlet header comprises a circular shape; and a second fluid circuit formed by: a second set of fins that extend radially and that are coaxial with each other; a second inlet header fluidly connected to and disposed on an upstream end of the second set of fins, wherein an annular shape of the second inlet header conforms to the circular shape of the first inlet header; a second outlet header fluidly connected to and disposed on a downstream end of the second set of fins, wherein an annular shape of the second outlet header conforms to the circular shape of the first outlet header; and a barrier layer surrounding and enclosing outward surfaces of at least one of the first fluid circuit and the second fluid circuit; and wherein: the first set of fins and the second set of fins form an alternating pattern in a circumferential direction such that each fin of the first set of fins is positioned between two fins of the second set of fins and each fin of the second set of fins is positioned between two fins of the first set of fins; a first fluid flows through the first fluid circuit and a second fluid flows through the second fluid circuit; and thermal energy is transferred between the first fluid and the second fluid via conduction. a first fluid circuit formed by: a first set of fins that extend radially and that are coaxial with each other; a first inlet header fluidly connected to and disposed on an upstream end of the first set of fins, wherein the first inlet header comprises a circular shape; and a first outlet header fluidly connected to and disposed on a downstream end of the first set of fins, wherein the first outlet header comprises a circular shape; and a first set of fins that extend radially and that are coaxial with each other; a first inlet header fluidly connected to and disposed on an upstream end of the first set of fins, wherein the first inlet header comprises a circular shape; and a first outlet header fluidly connected to and disposed on a downstream end of the first set of fins, wherein the first outlet header comprises a circular shape; and a second fluid circuit formed by: a second set of fins that extend radially and that are coaxial with each other; a second inlet header fluidly connected to and disposed on an upstream end of the second set of fins, wherein an annular shape of the second inlet header conforms to the circular shape of the first inlet header; a second outlet header fluidly connected to and disposed on a downstream end of the second set of fins, wherein an annular shape of the second outlet header conforms to the circular shape of the first outlet header; and a barrier layer surrounding and enclosing outward surfaces of at least one of the first fluid circuit and the second fluid circuit; and wherein: the first set of fins and the second set of fins form an alternating pattern in a circumferential direction such that each fin of the first set of fins is positioned between two fins of the second set of fins and each fin of the second set of fins is positioned between two fins of the first set of fins; a first fluid flows through the first fluid circuit and a second fluid flows through the second fluid circuit; and thermal energy is transferred between the first fluid and the second fluid via conduction. a second set of fins that extend radially and that are coaxial with each other; a second inlet header fluidly connected to and disposed on an upstream end of the second set of fins, wherein an annular shape of the second inlet header conforms to the circular shape of the first inlet header; a second outlet header fluidly connected to and disposed on a downstream end of the second set of fins, wherein an annular shape of the second outlet header conforms to the circular shape of the first outlet header; and a barrier layer surrounding and enclosing outward surfaces of at least one of the first fluid circuit and the second fluid circuit; and wherein: the first set of fins and the second set of fins form an alternating pattern in a circumferential direction such that each fin of the first set of fins is positioned between two fins of the second set of fins and each fin of the second set of fins is positioned between two fins of the first set of fins; a first fluid flows through the first fluid circuit and a second fluid flows through the second fluid circuit; and thermal energy is transferred between the first fluid and the second fluid via conduction. the first set of fins and the second set of fins form an alternating pattern in a circumferential direction such that each fin of the first set of fins is positioned between two fins of the second set of fins and each fin of the second set of fins is positioned between two fins of the first set of fins; a first fluid flows through the first fluid circuit and a second fluid flows through the second fluid circuit; and thermal energy is transferred between the first fluid and the second fluid via conduction.