Cryogenic Cooling Flow Control for Electric Fan Propulsion Motors

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Solution Overview

Problem

Gas turbine engines face inefficiencies due to material constraints, leading to suboptimal design and limited placement on aircraft, while electric propulsion motors are limited by power density and heating effects, necessitating improved cooling systems for enhanced performance.

Innovation Solution

A cryogenic cooling system that includes a controller and flow control assembly to manage the flow rate and state of a working fluid, ensuring efficient cooling of electric fan propulsion motors by transitioning between pre-cooling and full cooling flows, and utilizing liquid air to maintain optimal operating conditions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Power

If electric propulsion motors are used to provide aircraft thrust, then power density and efficiency are improved, but heating effects increase and reliability deteriorates

Engineering Contradiction:
Improvepower densityVSAvoidreliability
Core Design Contradiction:
PowerVSReliability

Solution Approach 1:

The patent employs phase change material (paraffin wax) that transitions from solid to liquid state during charging cycles. This phase transition absorbs excess heat energy, preventing thermal buildup that would compromise motor reliability while maintaining the high power density benefits of electric propulsion motors.

Inventive Principle:
Principle #36Phase transitions

Solution Approach 2:

The patent introduces a thermal management system with phase change material as an intermediary between the electric propulsion motor and its environment. This mediator absorbs and stores thermal energy, protecting the motor from harmful heating effects while allowing the motor to operate at high power density levels.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Loss of energy

If gas turbine engines are designed with balanced thermodynamic cycles, then efficiency is improved, but material constraints limit temperature and pressure which reduces power output

Engineering Contradiction:
ImproveefficiencyVSAvoidpower output
Core Design Contradiction:
Loss of energyVSPower

Solution Approach 1:

The patent changes the thermodynamic parameters of the gas turbine engine by incorporating intercooling and reheating processes. These parameter changes allow the engine to operate at higher effective temperatures and pressures without exceeding material limits, thereby increasing power output while maintaining efficiency through the balanced thermodynamic cycle.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent segments the thermodynamic cycle into multiple stages with intermediate cooling and heating processes. This segmentation allows the engine to achieve higher overall pressure ratios and temperature differentials across the turbine, increasing power output while maintaining material constraints within safe operating limits.

Inventive Principle:
Principle #1Segmentation

3Temperature

If cooling air branch occurs in gas turbine engine, then cooling is provided, but work is lost without imparting motive force to turbomachinery

Engineering Contradiction:
ImprovecoolingVSAvoidwork loss
Core Design Contradiction:
TemperatureVSLoss of energy

Solution Approach 1:

The patent uses a separate intercooling system that replicates the cooling function without extracting work from the main thermodynamic cycle. By using a dedicated cooling loop with phase change material, the system provides necessary cooling while avoiding the work loss associated with traditional cooling air branches.

Inventive Principle:
Principle #26Copying

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

This system enhances the power density and efficiency of electric fan propulsion motors by effectively managing cooling flows, allowing for rapid power transitions and reducing thermal stress, thereby improving aircraft performance and efficiency.

Implementation Method 1

a phase change material (PCM) cooling system may be used to cool the electric propulsion motor during charging cycles

Methodology Applied
Scientific EffectPhase transition: Phase Change

Implementation Method 2

The heat exchanger system may include a first heat exchanger configured to cool the working fluid

Methodology Applied
Scientific EffectHeat transfer: Heat Exchanger

Data Source

PatentEP3552971B1Propulsion system cooling control
Publication Date: 2024.04.24 RTX CORP
  • EP3552971B1 patent drawingFigure 1
  • EP3552971B1 patent drawingFigure 2
  • EP3552971B1 patent drawingFigure 3

AI summary

A propulsion system includes an electric fan propulsion motor (818) with a plurality of propulsion motor windings (820). The propulsion system also includes a means for controlling a flow rate of a working fluid (3206) through a cryogenic working fluid flow control assembly (3204) to the propulsion motor windings (820).