Hydrogen Steam Turbine Cycle With Intercooling and Water Recovery

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Solution Overview

Problem

Existing gas turbine engines in aircraft face challenges in efficiently using hydrogen or methane fuels due to weight and volume penalties associated with fuel storage, requiring improved propulsion efficiency to carry these fuels feasibly, and conventional alternatives suffer from combustion byproduct issues.

Innovation Solution

A hydrogen steam and inter-cooled turbine engine system that incorporates a semi-closed loop steam injection cycle, utilizing exhaust heat to generate steam for improved performance by increasing turbine mass flow and power output, and includes features like steam injection, water injection for intercooling, and hybrid electric systems to reduce weight and volume of fuel storage components.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-generated harmful factors

If hydrogen or methane fuel is used in gas turbine engines, then combustion efficiency and environmental performance are improved, but fuel storage volume and weight increase significantly

Engineering Contradiction:
Improvecombustion byproductsVSAvoidfuel storage volume
Core Design Contradiction:
Object-generated harmful factorsVSVolume of moving object

Solution Approach 1:

The patent changes the physical state of hydrogen fuel from gas to liquid (cryogenic storage), and further to supercritical fluid state. This parameter change dramatically reduces storage volume - supercritical hydrogen occupies approximately 1/1000th of the volume of gaseous hydrogen at standard conditions, making fuel storage feasible for aircraft applications.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent transitions from storing hydrogen in its conventional gaseous or liquid form to utilizing it in a supercritical state, effectively adding a new dimensional parameter (pressure-temperature state) to the storage solution. This allows the fuel to be stored in a compact form factor suitable for aircraft while maintaining high energy density.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

2Adaptability or versatility

If liquid hydrogen fuel is stored onboard aircraft, then hydrogen propulsion is enabled, but weight and volumetric penalties increase by 15% to 25%

Engineering Contradiction:
Improvehydrogen propulsion capabilityVSAvoidfuel storage weight
Core Design Contradiction:
Adaptability or versatilityVSWeight of moving object

Solution Approach 1:

By transitioning hydrogen to a supercritical state through controlled pressure and temperature parameters, the patent achieves a density increase that directly reduces storage volume and associated weight penalties. The supercritical state allows hydrogen to be stored with approximately 15-25% less weight and volume compared to conventional liquid hydrogen storage systems.

Inventive Principle:
Principle #35Parameter changes

3Reliability

If conventional liquid fuel is used in gas turbine engines, then established technology is maintained, but combustion byproduct emissions increase

Engineering Contradiction:
Improvetechnology maturityVSAvoidcombustion byproduct emissions
Core Design Contradiction:
ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The patent maintains the proven gas turbine engine technology while changing the fuel state parameter to supercritical hydrogen. This allows the engine to operate with established, reliable technology while achieving zero-carbon emissions, as hydrogen combustion produces only water vapor rather than CO2 and other harmful byproducts associated with hydrocarbon fuels.

Inventive Principle:
Principle #35Parameter changes

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

The engine system achieves a significant reduction in fuel volume and weight, enhancing mission energy efficiency by up to 60%, while maintaining stable combustion and reducing NOx emissions, with improved thermal efficiency and reduced evaporator and condenser size.

Implementation Method 1

an evaporator downstream from the burner and arranged to use heat from the exhaust to evaporate water

Methodology Applied
Scientific EffectEvaporation: Evaporation

Implementation Method 2

the evaporator downstream from the burner and arranged to use heat from the exhaust to evaporate water

Methodology Applied
Scientific EffectHeat transfer: Heat Exchanger

Implementation Method 3

a condenser arranged downstream from the evaporator

Methodology Applied
Scientific EffectCondensation: Condensation

Implementation Method 4

water injection for intercooling

Methodology Applied
Scientific EffectIntercooling: Cooling

Implementation Method 5

a turbine section across which the resultant combustion products are expanded. The expansion of the combustion products drives the turbine section to rotate.

Methodology Applied
Scientific EffectExpansion:

Implementation Method 6

a compressor section that compresses air

Methodology Applied
Scientific EffectCompression: Compression

Implementation Method 7

a combustor section in which the compressed air is mixed with a fuel and ignited

Methodology Applied
Scientific EffectCombustion: Combustion

Data Source

PatentEP4257814B1Hydrogen steam and inter-cooled turbine engine
Publication Date: 2025.11.05 RTX CORP
  • EP4257814B1 patent drawingFigure 1
  • EP4257814B1 patent drawingFigure 2

AI summary

A propulsion system for an aircraft (200) includes a fan (102) and a low pressure turbine (114) operably coupled to a first shaft (116), a low pressure compressor (104) and an intermediate pressure turbine (112) operably coupled to a second shaft (118), and a high pressure compressor (106) and a high pressure turbine (110) operably coupled to a third shaft (120). A burner (108) is arranged between the high pressure compressor (106) and the high pressure turbine (110), with a main flow path (124) defined through the propulsion system. A hydrogen fuel system is configured to supply hydrogen fuel to the burner (108). A condenser (134) is arranged along the main flow path (124) and configured to extract water from exhaust from the burner (108). An evaporator (132) is arranged along the main flow path (124) and configured to receive a portion of the water to generate steam which is injected into the main flow path (124) upstream from the evaporator (132).