Flight Vehicle Power System With Closed-Loop Heat Transfer

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Solution Overview

Problem

Traditional recuperators for small gas turbines are heavy due to the use of nickel alloys, leading to low compression ratios and inefficient power systems in flight vehicles.

Innovation Solution

A power system for flight vehicles that includes a first power plant with a closed fluid loop and a compressor, utilizing a thermal engine to operate independently of the primary propulsor, and a second power plant to combust a fuel-fluid mixture, where heat from the second power plant is used to thermally transfer energy to the working fluid in the closed loop, eliminating the need for a traditional recuperator.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If a traditional recuperator made of nickel alloys is used, then the recuperator can withstand exhaust gas temperatures, but the weight of the power system increases significantly

Engineering Contradiction:
Improveexhaust gas temperature resistanceVSAvoidpower system weight
Core Design Contradiction:
TemperatureVSWeight of moving object

Solution Approach 1:

The patent changes the material parameters from traditional nickel alloys to graphite composite materials, which have different thermal and mechanical properties. Graphite can withstand high temperatures while being significantly lighter, thus resolving the contradiction between temperature resistance and weight reduction

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent employs composite materials (graphite) instead of traditional homogeneous nickel alloys. These composite materials provide both the necessary thermal resistance for withstanding exhaust gas temperatures and the weight reduction benefit, simultaneously addressing both requirements

Inventive Principle:
Principle #40Composite materials

2Device complexity

If a traditional solid-state recuperator is used, then the structure is simple, but the weight increases due to nickel alloy materials

Engineering Contradiction:
Improverecuperator structure simplicityVSAvoidrecuperator weight
Core Design Contradiction:
Device complexityVSWeight of moving object

Solution Approach 1:

The patent changes the material composition from nickel alloys to graphite composites, maintaining the simple solid-state recuperator structure while dramatically reducing weight. The graphite material preserves the structural simplicity requirement while eliminating the weight penalty of traditional materials

Inventive Principle:
Principle #35Parameter changes

3Volume of moving object

If a small gas turbine is used, then the power system is compact, but the compression ratio is limited by physics and manufacturability

Engineering Contradiction:
Improvegas turbine sizeVSAvoidcompression ratio
Core Design Contradiction:
Volume of moving objectVSStress or pressure

Solution Approach 1:

The patent uses graphite composite materials in the gas turbine construction, which enable higher compression ratios in compact designs. These materials provide the necessary strength-to-weight ratio and thermal resistance to achieve higher compression ratios without increasing the physical size of the turbine beyond compact dimensions

Inventive Principle:
Principle #40Composite 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 achieves a higher power-to-weight ratio and thermodynamic efficiency, allowing the primary propulsor to operate continuously while providing power to other systems, reducing weight and improving thermal management.

Implementation Method 1

a thermal engine coupled to the compressor and configured to operate the compressor

Methodology Applied
Scientific EffectThermal engine: Heat Engine

Implementation Method 2

a compressor configured to compress the working fluid

Methodology Applied
Scientific EffectCompression: Compression

Implementation Method 3

heat from the second power plant is used to thermally transfer energy to the working fluid in the closed loop

Methodology Applied
Scientific EffectThermal energy transfer: Conduction (thermal)

Data Source

PatentEP4603686A1Power system for a flight vehicle
Publication Date: 2025.08.20 THE BOEING CO
  • EP4603686A1 patent drawingFigure 1
  • EP4603686A1 patent drawingFigure 2
  • EP4603686A1 patent drawingFigure 3

AI summary

A power system for a flight vehicle includes a first power plant and a second power plant. The second power plant is configured to combust a fuel-fluid mixture. The first power plant includes a closed fluid loop configured to contain a working fluid. The first power plant includes a compressor configured to compress the working fluid. The first power plant includes a thermal engine coupled to the compressor and configured to operate the compressor. In certain configurations, the first power plant includes a container encasing the closed fluid loop, the compressor, and the thermal engine. In various configurations, the power system is coupled to a primary propulsor of the flight vehicle and configured to provide power to the primary propulsor. The power system is separate from the primary propulsor such that the primary propulsor is continuously operable independently of the power system to provide power to operate the flight vehicle.