US Patent 10184400 Methods of cooling a fluid using an annular heat exchanger

Methods of cooling a hot fluid in an annular duct of a gas turbine engine are provided. The method can include directing the hot fluid through a plurality of cooling channels that are radially layered within the annular duct to define a heat transfer area, and passing a cooling fluid through the annular duct such that the cooling fluid passes between the radially layered cooling channels. Additionally or alternatively, the method can include passing the hot fluid into a first inner radial tube, through a plurality of cooling channels defined within a plurality of curvilinear plates that are radially layered within the annular duct, and into a second inner radial tube; and passing a cooling fluid through the annular duct.