# US 12,180,893 B2 · Hydrogen steam injected turbine engine with turboexpander heat recovery > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 12,180,893 B2 - Document ID: US12180893B2 - Status: Granted - Kind: B2 - Application number: 18/329,044 - Filed: 2023-06-05 - Published: 2024-08-01 - Granted: 2024-12-31 - Earliest claimed: 2023-01-27 - Assignees: Rtx Corporation - Applicants: Raytheon Technologies Corporation - Inventors: Neil J. Terwilliger; Joseph B. Staubach - Web page: https://patentgrep.com/patent/US12180893B2 ## CPC - F02C 7/141: of working fluid - F02C 7/224: Heating fuel before feeding to the burner - F02C 3/22: the fuel or oxidant being gaseous at standard temperature and pressure (F02C3/28 takes precedence) - F02C 3/24: the fuel or oxidant being liquid at standard temperature and pressure - F02C 3/30: Adding water, steam or other fluids {for influencing combustion, e.g. to obtain cleaner exhaust gases (F02C7/141, F02C7/30, F01D21/00, F01K21/04, F23D11/10 take precedence)} - F02C 7/16: characterised by cooling medium - F05D 2260/213: by the provision of a heat exchanger within the cooling circuit - F02C: GAS-TURBINE PLANTS; AIR INTAKES FOR JET-PROPULSION PLANTS; CONTROLLING FUEL SUPPLY IN AIR-BREATHING JET-PROPULSION PLANTS (construction of turbines F01D; jet-propulsion plants F02K; construction of compressors or fans F04; generating combustion products of high pressure or high velocity F23R; using gas turbines in compression refrigeration plants F25B11/00) - F05D: INDEXING SCHEME FOR ASPECTS RELATING TO NON-POSITIVE-DISPLACEMENT MACHINES OR ENGINES, GAS-TURBINES OR JET-PROPULSION PLANTS ## Abstract A propulsion system for an aircraft includes a core engine that includes a core flow path where air is compressed in a compressor section, communicated to a combustor section, mixed with a gaseous fuel and ignited to generate an exhaust gas flow that is expanded through a turbine section. A fuel system supplies a fuel to the combustor through a fuel flow path, a first heat exchanger thermally communicates a first heat load into a cooling flow, a turboexpander where a heated cooling flow from the first heat exchanger is expanded to generate shaft power and cooled to provide a cooled cooling flow, and a second heat exchanger thermally communicates a second heat load to the cooled cooling flow that is communicated from the turboexpander, cooling flow from the second heat exchanger is communicated to the combustor section. ## Claims ### Claim 1 A propulsion system for an aircraft comprising: a core engine including a core flow path where air is compressed in a compressor section, communicated to a combustor section, mixed with a gaseous fuel and ignited to generate an exhaust gas flow that is expanded through a turbine section; a fuel system for supplying the fuel to the combustor through a fuel flow path, wherein the fuel flow comprises a cryogenic fuel; a first heat exchanger thermally communicating a first heat load into a flow of the cryogenic fuel; a turboexpander where a heated flow of the cryogenic fuel from the first heat exchanger is expanded to generate shaft power and cooled to provide a cooled cryogenic fuel flow; a condenser comprising a second heat exchanger configured to extract water from the exhaust gas flow, wherein the cryogenic fuel flow is communicated from the turboexpander through the condenser to accept a second heat load to cool the exhaust gas flow and from the condenser to the combustor section; an evaporator configured to heat a portion of water extracted by the condenser to generate a steam flow for injection into the core flow path; and a third heat exchanger downstream of the turboexpander and upstream of the condenser. ### Claim 2 (depends on 1) The propulsion system as recited in claim 1, including a bypass valve where cooled cooling flow from the turboexpander is directed to bypass the second heat exchanger and is communicated directly to the combustor. ### Claim 3 (depends on 1) The propulsion system as recited in claim 1, wherein the turboexpander drives an engine accessory. ### Claim 4 (depends on 1) The propulsion system as recited in claim 1, wherein the turboexpander drives a primary shaft of the engine. ### Claim 5 (depends on 1) The propulsion system as recited in claim 1, wherein the first heat load comprises at least one of waste heat from an electric system, a lubrication system heat load, an aircraft system heat load, heat from condensation, or cooling of a thermal bus that collects multiple heat loads. ### Claim 6 (depends on 1) The propulsion system as recited in claim 1, wherein the condenser is in communication with a bypass airflow path for cooling the exhaust gas flow during aircraft operation. ### Claim 7 (depends on 6) The propulsion system as recited in claim 6, including a water storage tank and the condenser communicates water to the water storage tank and a first pump is configured to move water from the storage tank to the evaporator. ### Claim 8 (depends on 1) The propulsion system as recited in claim 1, wherein the turbine section includes at least a low pressure-turbine, a high-pressure turbine and an intermediate pressure turbine and the compressor section includes a high pressure compressor coupled to the high pressure turbine through a high shaft and a low pressure compressor coupled to the intermediate pressure turbine through an intermediate shaft. ### Claim 9 (depends on 8) The propulsion system as recited in claim 8, including a gearbox coupled to a low shaft for driving a fan at a speed lower than the low-pressure turbine. ### Claim 10 A propulsion system for an aircraft comprising: a core engine including a core flow path where air is compressed in a compressor section, communicated to a combustor section, mixed with a fuel and ignited to generate an exhaust gas flow that is expanded through a turbine section; a fuel system for storing and pressurizing fuel as a liquid, boiling the fuel, and supplying a gaseous fuel to the combustor through a fuel flow path; a first heat exchanger thermally communicating a first heat load into a flow of the gaseous fuel; a turboexpander where heated fuel flow from the first heat exchanger is expanded to generate shaft power and cooled to provide a cooled gaseous fuel flow; a second heat exchanger providing a second source of heat that is input into a first portion of the cooled gaseous fuel from the turboexpander, wherein the reheated fuel flow is communicated to the combustor; and a third heat exchanger receiving a second portion of the cooled gaseous fuel flow from the turboexpander and transferring an additional heat load into the cooled gaseous fuel flow before communication to the combustor section. ### Claim 11 (depends on 10) The propulsion system as recited in claim 10, wherein the second heat exchanger is a condenser. ### Claim 12 (depends on 11) The propulsion system as recited in claim 11, wherein the condenser is in thermal communication with a bypass airflow passage for cooling the exhaust gas flow in the condenser during aircraft operation. ### Claim 13 (depends on 11) The propulsion system as recited in claim 11, including a bypass valve where fuel flow from the turboexpander is directed to bypass the condenser cooling flow path and is communicated directly to the combustor. ### Claim 14 (depends on 10) The propulsion system as recited in claim 10, wherein the first heat load comprises at least one of an electrical heat load, a lubrication system heat load or an aircraft system heat load. ### Claim 15 A method of recovering thermal energy from a cryogenic fuel flow of an aircraft propulsion system, the method comprising: configuring a core engine to generate an exhaust gas flow from a cryogenic fuel; configuring a condenser to extract water from the exhaust gas flow with a cooling cryogenic fuel flow; configuring an evaporator generate a steam flow by heating extracted water from the condenser with a portion of the exhaust gas flow; configuring a first heat exchanger to thermal communicate a first heat load into a flow of the cryogenic fuel; configuring a turboexpander to expand and cool a heated cryogenic fuel flow communicated from the first heat exchanger to generate shaft power and generate a cooled fuel flow; and configuring a condenser cooling flow path from the turboexpander to the condenser to thermally communicate a first portion of the cooled fuel flow with the exhaust gas flow for cooling the exhaust gas flow to liquify water in the exhaust gas flow; providing a fuel flow path for a fuel flow from the condenser to a combustor; and configuring an additional heat exchanger to input an additional amount of heat into a second portion of the cooled fuel flow from the turboexpander before communication into the combustor. ### Claim 16 (depends on 15) The method as recited in claim 15, further comprising directing a portion of the cooled fuel flow from the turboexpander to bypass the condenser cooling flow path and flow directly to the combustor.