Closed-Loop Hydraulic System for Cryogenic Hydrogen Heat Management

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Solution Overview

Problem

Managing the temperature and safety of cryogenic hydrogen fuel in gas turbine engines, as well as controlling actuators, is challenging due to the low temperature and compressibility of hydrogen, and dual-fuel systems with hydrogen and hydrocarbon fuels are complex and pose safety issues.

Innovation Solution

A hydraulic system with a closed-loop conduit, heat exchangers for temperature management, and a hydraulic pump to maintain higher pressure in the hydraulic system, reducing the risk of hydrogen leaks and system overpressure, and incorporating a high-pressure sub-loop for actuator operation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If multiple hydrogen fuel heat exchangers are used to manage temperatures of hydrogen fuel and engine fluids, then temperature management capability is improved, but system complexity, weight, cost, and safety risks increase

Engineering Contradiction:
Improvetemperature management capabilityVSAvoidsystem complexity
Core Design Contradiction:
TemperatureVSDevice complexity

Solution Approach 1:

The patent combines multiple temperature management functions into a single hydrogen fuel heat exchanger. This heat exchanger simultaneously cools hydraulic fluid and manages hydrogen fuel temperature, eliminating the need for separate heat exchangers for each fluid. The merging reduces system complexity, weight, and cost while maintaining effective temperature management capability.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The hydrogen fuel heat exchanger is designed to perform multiple functions: cooling hydraulic fluid, managing hydrogen fuel temperature, and potentially serving as a thermal energy storage medium. This multi-functional design eliminates the need for dedicated heat exchangers for each function, reducing overall system complexity and component count.

Inventive Principle:
Principle #6Universality (Multi-functionality)

2Power

If hydraulic pump provides high pressure in the hydraulic system, then actuator performance is improved, but risk of hydrogen leaks and system overpressure events increases

Engineering Contradiction:
Improveactuator performanceVSAvoidsafety risk
Core Design Contradiction:
PowerVSReliability

Solution Approach 1:

The system applies preliminary anti-action by pre-establishing a pressure differential across the hydrogen fuel heat exchanger, with hydraulic fluid pressure maintained above hydrogen fuel pressure. This preventive pressure relationship ensures that any potential leak would flow from the hydraulic side to the fuel side, preventing hydrogen leakage into the hydraulic system and eliminating the need for complex safety valves or rupture discs.

Inventive Principle:
Principle #9Preliminary anti-action

3Adaptability or versatility

If dual-fuel system with hydrogen and hydrocarbon fuels is implemented, then fuel availability and performance are improved, but system complexity and safety issues increase

Engineering Contradiction:
Improvefuel availabilityVSAvoidsystem complexity
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The hydraulic fluid serves as an intermediary thermal management medium for both hydrogen and hydrocarbon fuels. Rather than requiring separate thermal management systems for each fuel type, the hydraulic fluid circulates through heat exchangers that can handle both fuel types, simplifying the dual-fuel system architecture while maintaining fuel versatility.

Inventive Principle:
Principle #24Intermediary (Mediator)

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 effectively manages hydrogen and hydrocarbon fuel temperatures with a single heat exchanger, reducing safety risks, weight, and cost, while enabling high-pressure actuators and efficient heat exchange.

Implementation Method 1

a first heat exchanger configured to exchange heat between hydrogen fuel and hydraulic fluid within the hydraulic fluid conduit

Methodology Applied
Scientific EffectHeat exchange: Heat Exchanger

Implementation Method 2

a further heat exchanger configured to exchange heat between the hydraulic fluid and one or more further engine fluids

Methodology Applied
Scientific EffectHeat exchange: Heat Exchanger

Implementation Method 3

a hydraulic pump configured to pressurise and drive hydraulic fluid flow through the hydraulic fluid conduit

Methodology Applied
Scientific EffectHydraulic pressure: Hydraulic Press

Data Source

PatentEP4636233A1Gas turbine engine hydraulic system
Publication Date: 2025.10.22 ROLLS ROYCE PLC
  • EP4636233A1 patent drawingFigure 1
  • EP4636233A1 patent drawingFigure 2
  • EP4636233A1 patent drawingFigure 3

AI summary

A hydraulic system for a hydrogen fuelled gas turbine engine (201). The hydraulic system comprises a closed-loop hydraulic fluid conduit (232), a first heat exchanger (230) configured to exchange heat between hydrogen fuel and hydraulic fluid within the hydraulic fluid conduit (232) and a further heat exchanger (316, 322) configured to exchange heat between the hydraulic fluid and one or more further engine fluids.