Gearbox-Driven Reverse Brayton Cooling for Aircraft Thermal Management

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Solution Overview

Problem

Aircraft gas turbine engines face inefficiencies due to the diversion of compressed air for powering the reverse Brayton cycle, which interrupts the thermodynamic cycle and results in energy wastage, weight, and complexity additions.

Innovation Solution

Mechanical energy from the gas turbine engine is transmitted to the reverse Brayton cycle through a gearbox, allowing the cycle to operate independently of engine thrust settings and reducing thermodynamic losses by using a gearbox to couple the engine shaft with the reverse Brayton cycle.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If compressed air is diverted from the propulsive engines to power the reverse Brayton cycle, then the thermal management system can operate, but the efficiency of the propulsive engines is reduced

Engineering Contradiction:

Improvethermal management system operationVSAvoidpropulsive engine efficiency

Core Design Contradiction:

ReliabilityVSLoss of energy

Solution Approach 1:

The invention extracts the thermal management system's power source from the propulsive engine's compressed air supply. Instead of diverting compressed air from the engine, a separate gas turbine engine is used exclusively to drive the reverse Brayton cycle, leaving the propulsive engine's thermodynamic cycle intact and eliminating energy loss from air diversion.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The invention segments the aircraft power system into independent functional units: the propulsive engine for thrust generation and a separate gas turbine engine for thermal management. This segmentation allows each system to operate independently without interfering with the other, preserving propulsive engine efficiency while enabling TMS operation.

Inventive Principle:

Principle #1Segmentation

2Temperature

If pressure regulators and heat exchangers are added to cool compressed air before it reaches the reverse Brayton cycle, then the air can be used for ECS, but weight and complexity of the system increase

Engineering Contradiction:

Improvecompressed air temperatureVSAvoidsystem weight and complexity

Core Design Contradiction:

TemperatureVSDevice complexity

Solution Approach 1:

The invention replaces the conventional pneumatic approach (using compressed air with mechanical cooling components) with a mechanical approach (using a gas turbine engine with a reverse Brayton cycle). The gas turbine inherently produces cooled air through its thermodynamic cycle, eliminating the need for separate pressure regulators and heat exchangers.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The invention changes the fundamental operating parameters of the thermal management system by using a gas turbine engine that naturally produces air at suitable pressure and temperature through its expansion cycle. This eliminates the need for additional components to adjust these parameters, reducing system complexity and weight.

Inventive Principle:

Principle #35Parameter changes

3Power

If compressed air is diverted from the propulsive engines, then the reverse Brayton cycle can be powered, but useful energy is wasted through anergy conversions

Engineering Contradiction:

Improvereverse Brayton cycle powerVSAvoidexergy conversion loss

Core Design Contradiction:

PowerVSLoss of energy

Solution Approach 1:

The gas turbine engine serves dual purposes: it generates power for the reverse Brayton cycle while simultaneously producing cooled air as a byproduct of its thermodynamic cycle. The system is self-sufficient, generating both the mechanical power and the conditioned air needed for the ECS without external energy conversion losses.

Inventive Principle:

Principle #25Self-service

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 approach enhances energy efficiency by preserving exergy and reducing anergy conversions, improving the overall performance of the gas turbine engine and thermal management system.

Implementation Method 1

Aircraft gas turbine engines deliver propulsive thrust for aircraft movement as well as provide energy for aircraft systems

Methodology Applied

Scientific EffectBrayton cycle: Brayton Cycle

Implementation Method 2

a large amount of useful energy is wasted by powering an RBC using compressed air from the propulsive engines

Methodology Applied

Scientific EffectHeat exchange: Heat Exchanger

Implementation Method 3

The TMS further includes management of energy and heat transfer among aircraft propulsion and electrical power generation units, fluid heat exchangers

Methodology Applied

Scientific EffectThermal energy transfer: Conduction (thermal)

Data Source

PatentUS11203949B2Mechanically driven air vehicle thermal management device

Publication Date: 2021.12.21 GENERAL ELECTRIC CO

AI summary

The present disclosure is directed to an aircraft power generation system including a reverse Brayton cycle system, a gas turbine engine, and a gearbox. The gas turbine engine includes a compressor section, a turbine section, and an engine shaft. The compressor section is arranged in serial flow arrangement with the turbine section. The engine shaft is rotatable with at least a portion of the compressor section and with at least a portion of the turbine section. The reverse Brayton cycle system includes a compressor, a driveshaft, a turbine, and a first exchanger. The driveshaft is rotatable with the compressor or the turbine, and the compressor, the first heat exchanger, and the turbine are in serial flow arrangement. The gearbox is configured to receive mechanical energy from the engine shaft and transmit mechanical energy to the reverse Brayton cycle system through the driveshaft.