Turbine engine assemblies including a turbine engine assembly having a turbine core comprising a compressor section, a combustion section, a turbine section, and a nozzle section, which are axially aligned, wherein the combustion section comprises a generally annular case having inner and outer walls, a heat exchanger comprising multiple passages in proximity to at least one of the inner and outer walls, with the passages arranged about at least a portion of the case and in fluid communication with each other such that fluid may flow through the passages and a cryogenic fuel system having a cryogenic fuel tank with a supply line coupled to one of the passages, wherein cryogenic fuel may be supplied from the cryogenic fuel tank, through the supply line, to the passages of the heat exchanger, where the fuel in the passages may be heated by the combustion section. The heat exchanger may be a single or multistage vaporizer.