Hydrogen Aircraft Fuel Heating with Catalytic Combustor and Heat Exchanger

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Solution Overview

Problem

Cryogenically stored hydrogen fuel requires significant energy expenditure to increase its temperature for delivery to an aircraft engine, and existing heating methods are inefficient and pose safety risks.

Innovation Solution

A fuel system utilizing a catalytic combustor with a mesh or open cell porous structure and catalyst materials like PtO2, PdO, Au, AgO2, RuO2, Co3O4, NiO, CuC, Fe2O3, MnO, or Cr2O3 to catalytically combust a portion of hydrogen fuel, combined with a heat exchanger to exchange heat with the main fuel conduit, and a controller to manage the fuel:air ratio for safe and efficient heating.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If conventional heating methods are used to heat cryogenic hydrogen, then the hydrogen can be delivered to the engine, but significant energy expenditure is required and safety risks arise

Engineering Contradiction:
Improvehydrogen fuel temperatureVSAvoidenergy expenditure
Core Design Contradiction:
TemperatureVSUse of energy by moving object

Solution Approach 1:

The patent converts the harmful effect of cryogenic temperatures into a beneficial feature by using a catalytic combustor that can operate at low temperatures. The catalyst facilitates hydrogen combustion at temperatures much lower than conventional methods, transforming the cold storage advantage into an energy-efficient heating solution that reduces overall energy expenditure while maintaining safety.

Inventive Principle:
Principle #22Blessing in disguise (Convert harm into benefit)

Solution Approach 2:

The patent changes the operational parameters of the heating process by using catalytic combustion instead of conventional combustion. This parameter change allows the system to heat hydrogen efficiently at lower temperatures, reducing the energy expenditure required while eliminating the safety risks associated with high-temperature conventional heating methods.

Inventive Principle:
Principle #35Parameter changes

2Temperature

If conventional heating methods are used to heat cryogenic hydrogen, then the hydrogen can be delivered to the engine, but safety risks are posed

Engineering Contradiction:
Improvehydrogen fuel temperatureVSAvoidsafety risks
Core Design Contradiction:
TemperatureVSObject-affected harmful factors

Solution Approach 1:

The patent converts the harmful effect of cryogenic temperatures into a beneficial feature by using a catalytic combustor that can operate at low temperatures. The catalyst facilitates hydrogen combustion at temperatures much lower than conventional methods, transforming the cold storage advantage into an energy-efficient heating solution that reduces overall energy expenditure while maintaining safety.

Inventive Principle:
Principle #22Blessing in disguise (Convert harm into benefit)

Solution Approach 2:

The catalytic combustor acts as an intermediary between the cryogenic hydrogen storage system and the engine combustor. It provides a controlled, low-temperature heating process that eliminates the safety risks of conventional high-temperature heating methods while still achieving the necessary temperature increase for engine delivery.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Productivity

If a catalytic combustor with mesh or open cell porous structure is used, then heating efficiency is improved, but device complexity increases

Engineering Contradiction:
Improveheating efficiencyVSAvoidcatalytic combustor structure
Core Design Contradiction:
ProductivityVSDevice complexity

Solution Approach 1:

The patent employs a mesh or open cell porous structure in the catalytic combustor to maximize the catalyst surface area exposed to hydrogen fuel. This porous material design significantly improves heating efficiency by providing numerous active sites for catalytic combustion while maintaining a relatively simple overall device structure that can be integrated into existing aircraft fuel systems.

Inventive Principle:
Principle #31Porous materials

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 system efficiently heats hydrogen fuel to the required temperature while reducing energy consumption and safety risks, allowing for reliable operation across varying fuel flow rates and temperatures, and minimizing bleed air requirements.

Implementation Method 1

a catalytic combustor configured to catalytically combust a portion of the hydrogen fuel

Methodology Applied
Scientific EffectCatalytic combustion: Catalysis

Implementation Method 2

flowing hydrogen and oxygen through a catalytic combustor to thereby catalytically combust hydrogen and oxygen

Methodology Applied
Scientific EffectCombustion: Combustion

Implementation Method 3

a heat exchanger configured to exchange heat between exhaust gases from the fuel heater and hydrogen fuel in the fuel conduit

Methodology Applied
Scientific EffectHeat exchange: Heat Exchanger

Implementation Method 4

exchanging heat between catalytically combusted hydrogen and fuel in the fuel conduit

Methodology Applied
Scientific EffectThermal energy transfer: Convection

Data Source

PatentEP4663914A1Aircraft fuel system
Publication Date: 2025.12.17 ROLLS ROYCE PLC
  • EP4663914A1 patent drawingFigure 1
  • EP4663914A1 patent drawingFigure 2
  • EP4663914A1 patent drawingFigure 3

AI summary

A fuel system for a hydrogen fuelled aircraft propulsion system (103) comprises a fuel tank (104) configured to store hydrogen fuel, a main fuel conduit (206) configured to provide fuel to a combustor (203) of a gas turbine engine (201), a fuel heater (208) comprising a catalytic combustor (304) configured to catalytically combust a portion of the hydrogen fuel prior to delivery to the combustor (203) and a heat exchanger (211) configured to exchange heat between exhaust gases from the fuel heater (208) and hydrogen fuel in the fuel conduit (206).