Compact Airfoil Bleed-Air Re-circulation Heat Exchanger

A system comprising:

• a compressor;
• a heat exchanger comprising
• a plurality of airfoils extending across an inlet to the compressor, wherein each of the plurality of airfoils comprises a leading edge and a trailing edge, and a longitudinal axis through the leading edge and the trailing edge, and wherein each of the plurality of airfoils further comprises
• a plurality of passages within the airfoil, wherein each of the plurality of passages extend along a transverse axis that is orthogonal to the longitudinal axis, and wherein each of the plurality of passages is in fluid communication with at least one adjacent one of the plurality of passages via at least one outlet,
• one or more serpentine flow paths that extend through the plurality of passages via the outlets to an internal cavity of the airfoil, and
• a plurality of micro-holes through a wall of the airfoil to fluidly connect the internal cavity of the airfoil to the inlet to the compressor;
• a combustor that is downstream from the compressor;
• and
• a bleed-air circuit that is configured to supply bleed air from the combustor to at least one of the plurality of passages in each of the plurality of airfoils.