Liquid Hydrogen Thermal Compression for Aircraft Fuel Delivery

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Solution Overview

Problem

Existing fuel systems for cryogenic fuels, such as liquid hydrogen, face challenges in maintaining low temperatures compatible with traditional pressurization methods, which are not suitable for introduction into a combustor.

Innovation Solution

A fuel delivery system utilizing thermal compression tanks to pressurize cryogenic fuels by exposing liquid fuel to thermal energy, controlled by a valve system and a controller, with optional heat exchangers to transform the fuel into a gas phase for combustor introduction.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Stress or pressure

If traditional pressurization methods are used for cryogenic fuel, then the fuel can be pressurized for combustor introduction, but the low temperature requirements of cryogenic fuels are not compatible with traditional fuel system components

Engineering Contradiction:
Improvefuel pressureVSAvoidfuel temperature
Core Design Contradiction:
Stress or pressureVSTemperature

Solution Approach 1:

The fuel system is divided into separate functional components: a storage tank for cryogenic fuel, a thermal compression tank for pressurization, and a combustor. This segmentation allows each component to operate at its optimal temperature and pressure conditions, resolving the incompatibility between cryogenic fuel temperature requirements and traditional pressurization components.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Traditional mechanical pressurization methods (such as mechanical pumps) are replaced with a thermal compression system. The thermal compression tank uses thermal energy to pressurize the liquid fuel, eliminating the need for mechanical pressurization components that cannot tolerate cryogenic temperatures.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

2Stress or pressure

If thermal energy is applied to pressurize liquid fuel, then the fuel pressure is elevated for combustor introduction, but the fuel must be transformed from liquid to gas phase

Engineering Contradiction:
Improvefuel pressureVSAvoidfuel phase transformation system
Core Design Contradiction:
Stress or pressureVSDevice complexity

Solution Approach 1:

The system utilizes phase transition of the fuel from liquid to gas as the mechanism for pressurization. Thermal energy applied to the thermal compression tank causes the liquid fuel to vaporize, and the resulting phase transition and thermal expansion generate the high pressure needed for combustor introduction, eliminating the need for separate pressurization devices.

Inventive Principle:
Principle #36Phase transitions

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

Effectively pressurizes cryogenic fuels without traditional pumps, ensuring compatible temperature and pressure for combustor operation, maintaining a continuous and uniform fuel flow.

Implementation Method 1

liquid fuel from the fuel storage tank is pressurized by exposure to thermal energy to elevate a pressure of the liquid fuel

Methodology Applied
Scientific EffectThermal compression: Heating

Implementation Method 2

a heat communication device that is in thermal communication (or thermal contact) with the thermal compression tank for communicating thermal energy to the liquid fuel within the thermal compression tank

Methodology Applied
Scientific EffectThermal conduction: Conduction (thermal)

Implementation Method 3

a heat exchanger that is downstream of the thermal compression tank where thermal energy is provided to transform the pressurized liquid fuel into a gas

Methodology Applied
Scientific EffectPhase change: Phase Change

Data Source

PatentEP4617481A1Liquid hydrogen fuel system with thermal compression
Publication Date: 2025.09.17 RTX CORP
  • EP4617481A1 patent drawingFigure 1
  • EP4617481A1 patent drawingFigure 2~4
  • EP4617481A1 patent drawingFigure 5

AI summary

A fuel delivery system (74) for an aircraft turbine engine assembly includes a storage tank (76) that is configured for storage of a cryogenic fuel in a liquid phase, at least one thermal compression tank (78) where liquid fuel from the storage tank (76) is pressurized by exposure to thermal energy to elevate a pressure of the liquid fuel, a heat communication device (136) that is in thermal communication with the thermal compression tank (78) for communicating thermal energy to the liquid fuel within the thermal compression tank (78), a valve system (92) for controlling the flow of pressurized liquid fuel into and out of the thermal compression tank (78), and a controller (100) that is programmed to operate the valve system (92) to release pressurized liquid fuel from the thermal compression tank (78) into a conduit for communication to a combustor (56).