A gas turbine engine heat exchange system, comprising: a first microchannel heat exchanger (MCHX) (108, 300) configured to transfer heat between a first air stream (114, 208, 322) and a working fluid, wherein the first MCHX (108, 300) comprises: a first plurality of air-passage layers (328, 700), wherein each air-passage layer (328, 700) of the first plurality of air-passage layers (328, 700) includes a first plurality of etched air-passage microchannels (320, 702) configured to allow passage of the first air stream (114, 208 322) therethrough; and a first plurality of working fluid layers (324, 500), wherein each working fluid layer (324, 500) of the first plurality of working fluid layers (324, 500) includes a first plurality of etched working fluid microchannels configured to allow passage of the working fluid therethrough, the first MCHX (108, 300) further comprising a first plurality of sealing layers (326, 600) bonded to the first plurality of working fluid layers (324, 500) such that a single sealing layer (326, 600) of the first plurality of sealing layers (326, 600) is bonded to a single working fluid layer (324, 500) of the first plurality of working fluid layers (324, 500) to create a first plurality of working and sealing layer sets, wherein each air-passage layer (328, 700) of the first plurality of air-passage layers (328, 700) is diffusion bonded between two working and sealing layer sets of the first plurality of working and sealing layer sets; characterized by wherein each working and sealing layer set of the first plurality of working and sealing layer sets comprises an etched internal intake manifold, wherein the etched internal intake manifold is configured to distribute the working fluid to the first plurality of etched working fluid microchannels, and an etched internal outtake manifold, wherein the etched internal outtake manifold is configured to receive the working fluid from the first plurality of etched working fluid microchannels; and wherein the etched intake manifold and the etched outtake manifold of each working and sealing layer set of the first plurality of working and sealing layer sets surround a plurality of supports (502, 504) configured to support a sealing layer (326, 600) of the first plurality of sealing layers (326, 600). a first plurality of air-passage layers (328, 700), wherein each air-passage layer (328, 700) of the first plurality of air-passage layers (328, 700) includes a first plurality of etched air-passage microchannels (320, 702) configured to allow passage of the first air stream (114, 208 322) therethrough; and a first plurality of working fluid layers (324, 500), wherein each working fluid layer (324, 500) of the first plurality of working fluid layers (324, 500) includes a first plurality of etched working fluid microchannels configured to allow passage of the working fluid therethrough, the first MCHX (108, 300) further comprising a first plurality of sealing layers (326, 600) bonded to the first plurality of working fluid layers (324, 500) such that a single sealing layer (326, 600) of the first plurality of sealing layers (326, 600) is bonded to a single working fluid layer (324, 500) of the first plurality of working fluid layers (324, 500) to create a first plurality of working and sealing layer sets, wherein each air-passage layer (328, 700) of the first plurality of air-passage layers (328, 700) is diffusion bonded between two working and sealing layer sets of the first plurality of working and sealing layer sets; characterized by wherein each working and sealing layer set of the first plurality of working and sealing layer sets comprises an etched internal intake manifold, wherein the etched internal intake manifold is configured to distribute the working fluid to the first plurality of etched working fluid microchannels, and an etched internal outtake manifold, wherein the etched internal outtake manifold is configured to receive the working fluid from the first plurality of etched working fluid microchannels; and wherein the etched intake manifold and the etched outtake manifold of each working and sealing layer set of the first plurality of working and sealing layer sets surround a plurality of supports (502, 504) configured to support a sealing layer (326, 600) of the first plurality of sealing layers (326, 600).