Heat exchanger with header embedded cooling channels

A gas turbine engine comprising:

• a heat exchanger positioned in a bypass flow path of the gas turbine engine, wherein the heat exchanger further comprises:
• a heat exchanger core comprising a cold side having a cold inlet and a cold outlet, and a hot side having a hot inlet and a hot outlet, wherein the cold side is configured to direct a first cooling fluid from the cold inlet to the cold outlet when the heat exchanger is in operation and the hot side is configured to direct a hot fluid from the hot inlet to the hot outlet when the heat exchanger is in operation;
• an inlet header coupled to the hot side of the heat exchanger core at the hot inlet, wherein the inlet header comprises an interior wall and an exterior wall spaced apart from the interior wall such that the interior wall defines an inlet duct and the interior wall and exterior wall define a fully annular cooling channel surrounding at least a portion of the inlet duct and the inlet duct is configured to direct the hot fluid though the inlet header to the hot side when the heat exchanger is in operation and wherein the exterior wall forms an outer structure of the inlet header and defines an outer shape of the inlet header;
• wherein the inlet duct is fluidly isolated from and thermally connected to the cooling channel, and wherein the cooling channel is configured to direct a second cooling fluid through the cooling channel when the heat exchanger is in operation;
• and
• wherein the heat exchanger core is positioned within a bypass duct of the gas turbine engine and receives air from a gas turbine engine bypass flow path as the first cooling fluid and the inlet header of the heat exchanger receives the hot fluid from a gas turbine engine core.

A method of operating a heat exchanger positioned within a gas turbine engine, the method comprising:

• positioning the heat exchanger in a bypass flow path of the gas turbine engine;
• flowing a bypass air flow through the bypass flow path of the gas turbine engine such that a first portion of the bypass air flow flows through a cold side of the heat exchanger as a first cooling fluid;
• flowing a hot fluid from a gas turbine engine core through an inlet duct of the inlet header to a hot side of the heat exchanger such that the hot fluid flows through the hot side of the heat exchanger;
• cooling the hot fluid flowing through the hot side of the heat by transferring heat from the hot fluid to the first cooling fluid flowing through the cold side of the heat exchanger, wherein the first cooling fluid and the hot fluid are fluidly isolated;
• and
• cooling the inlet header by flowing a second cooling fluid through a fully annular cooling channel surrounding at least a portion of an inlet duct of the inlet header wherein the inlet header includes interior walls that define the cooling channel and exterior walls that form an outer structure of the inlet header and define an outer shape of the inlet header.