Cryogenic fuel semi-closed recirculating bottoming cycle

A gas turbine engine assembly comprising:

• a compressor, a combustor and a turbine coupled to an engine shaft, wherein a mix of air and fuel is ignited in the combustor to generate an exhaust gas flow that is expanded through the main turbine to drive the engine shaft and subsequently exhausted through an exhaust nozzle;
• a propulsive fan driven by the engine shaft;
• a cryogenic fuel system comprising a cryogenic fuel storage tank;
• a fuel flow path where cryogenic fuel flow is circulated from upstream in a direction downstream to the combustor;
• a first heat exchanger where heat input into the cryogenic fuel flow downstream of the first heat exchanger is used to heat the cryogenic fuel flow from the cryogenic fuel storage tank;
• a second heat exchanger where thermal energy from a heat source is input into the cryogenic fuel flow downstream from the first heat exchanger;
• a bottoming cycle system comprising a bottoming compressor configured to pressurize at least a portion of the cryogenic fuel flow exhausted from the first heat exchanger and a turboexpander configured to generate shaft power from expansion of the cryogenic fuel flow exhausted from at least one of the first heat exchanger and the second heat exchanger.

A method of assembling an aircraft propulsion system comprising assembling a core engine comprising a combustor where a cryogenic fuel is mixed with compressed air and ignited to generate an exhaust gas flow;

• assembling a propulsive fan configured to be driven by shaft power generated by the core engine;
• assembling a cryogenic fuel system comprising a cryogenic fuel storage tank and a fuel flow path where a fuel flow is circulated from upstream in a downstream direction to the combustor of the core engine;
• assembling a first heat exchanger where heat input into the fuel flow downstream of the heat exchanger is input into the fuel flow is used to heat the fuel flow from the cryogenic fuel storage tank;
• assembling a second heat exchanger where thermal energy from a heat source is input into the fuel flow from the core engine downstream of the first heat exchanger;
• and
• assembling a bottoming cycle system comprising a bottoming compressor configured to pressurize the fuel flow exhausted from the first heat exchanger and a turboexpander configured to generate shaft power from expansion of the fuel flow exhausted from at least one of the first heat exchanger and the second heat exchanger.