Partial exhaust condensation with cryogenic assisted bottoming cycle

An aircraft propulsion system comprising:

• a core engine comprising a combustor where a cryogenic fuel is mixed with compressed air and ignited to generate an exhaust gas flow;
• a propulsive fan driven by the core engine;
• a bottoming cycle where a working fluid is circulated within a closed circuit comprising a bottoming compressor and a bottoming turbine, wherein the working fluid is compressed in the bottoming compressor and expanded through the bottoming turbine to generate shaft power;
• a first heat exchanger where a portion of thermal energy from the exhaust gas flow is communicated to the working fluid of the bottoming cycle;
• a fuel system comprising a cryogenic fuel storage tank and a fuel flow path for routing the cryogenic fuel to the combustor;
• a fuel/working fluid heat exchanger where a portion of thermal energy from the working fluid is communicated to the cryogenic fuel to cool the working fluid exhausted from the bottoming turbine and before the bottoming compressor;
• a water recovery system comprising a condenser where the exhaust gas flow is cooled by a flow of the cryogenic fuel to condense water;
• a second heat exchanger disposed downstream of the first heat exchanger, wherein the exhaust gas flow is cooled by a cooling airflow within the second heat exchanger prior to the condenser;
• and
• a steam generation system comprising an evaporator where water is heated to generate a steam flow, wherein the first heat exchanger is disposed between the evaporator and the condenser such that heat from the exhaust gas flow is cooled by water in the evaporator and a flow of the working fluid in the first heat exchanger before being cooled by the flow of the cryogenic fuel in the condenser.

A gas turbine engine assembly comprising:

• a core engine comprising a compressor, a combustor, and a turbine, wherein a cryogenic fuel is mixed with compressed air and ignited in the combustor to generate an exhaust gas flow that is expanded through the turbine to generate shaft power;
• a bottoming cycle where a working fluid is circulated within a closed circuit comprising a bottoming compressor and a bottoming turbine, wherein the working fluid is compressed in the bottoming compressor and expanded through the bottoming turbine to generate shaft power;
• a first heat exchanger where a portion of thermal energy from the exhaust gas flow is communicated to the working fluid of the bottoming cycle;
• a fuel system comprising a cryogenic fuel storage tank and a fuel flow path for routing a flow of cryogenic fuel to the combustor;
• a fuel/working fluid heat exchanger where a portion of thermal energy from the working fluid is communicated to the cryogenic fuel to cool the working fluid exhausted from the bottoming turbine and before the bottoming compressor;
• a water recovery system comprising a condenser where the exhaust gas flow is cooled by the cryogenic fuel to condense water;
• a second heat exchanger disposed downstream of the first heat exchanger, the exhaust gas flow is cooled by a cooling airflow within the second heat exchanger prior to the condenser;
• and
• a steam generation system comprising an evaporator where water is heated to generate a steam flow, wherein the evaporator is disposed upstream of the first heat exchanger such that the heat from the exhaust gas flow is communicated to generate the steam flow before being communicated to heat the working fluid of the bottoming cycle.

A gas turbine engine assembly comprising:

• a core engine comprising a compressor, a combustor, and a turbine, wherein a cryogenic fuel is mixed with compressed air and ignited in the combustor to generate an exhaust gas flow that is expanded through the turbine to generate shaft power;
• a bottoming cycle where a working fluid is circulated within a closed circuit comprising a bottoming compressor and a bottoming turbine, wherein the working fluid is compressed in the bottoming compressor and expanded through the bottoming turbine to generate shaft power;
• a first heat exchanger where a portion of thermal energy from the exhaust gas flow is communicated to the working fluid of the bottoming cycle;
• a fuel system comprising a cryogenic fuel storage tank and a fuel flow path for routing a flow of cryogenic fuel to the combustor;
• a fuel/working fluid heat exchanger where a portion of thermal energy from the working fluid is communicated to the cryogenic fuel to cool the working fluid exhausted from the bottoming turbine and before the bottoming compressor;
• a water recovery system comprising a condenser where the exhaust gas flow is cooled by the cryogenic fuel to condense water;
• a second heat exchanger disposed downstream of the first heat exchanger, the exhaust gas flow is cooled by a cooling airflow within the second heat exchanger prior to the condenser;
• and a steam generation system comprising an evaporator where water is heated to generate a steam flow, wherein the first heat exchanger is disposed between the evaporator and the condenser such that heat from the exhaust gas flow is cooled by water in the evaporator and a flow of the working fluid in the first heat exchanger before being cooled by a flow of the cryogenic fuel in the condenser.

A method of operating an aircraft propulsion system comprising:

• generating an exhaust gas flow within a core engine for expansion through a turbine to generate shaft power;
• recovering water from a portion of the exhaust gas flow in a water recovery system comprising a condenser where the portion of the exhaust gas flow is cooled by a flow of cryogenic fuel to condense water;
• heating a working fluid of a bottoming cycle with at least a portion of the exhaust gas flow in a first heat exchanger and expanding the heated working fluid through a bottoming turbine to generate shaft power;
• cooling the portion of the exhaust gas flow with a bypass flow in a second heat exchanger before cooling with the flow of cryogenic fuel in the condenser;
• cooling the working fluid with the flow of cryogenic fuel before cooling the exhaust gas flow in the condenser;
• and
• heating a portion of water recovered from the exhaust gas flow with an evaporator to generate a steam flow for injection into the core engine, wherein the evaporator is disposed upstream of the first heat exchanger such that the heat from the exhaust gas flow is communicated to generate the steam flow before being communicated to heat the working fluid of the bottoming cycle.