Reverse Brayton Thermal Management via Gearbox-Driven Engine Power
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Solution Overview
Problem
Aircraft gas turbine engines face inefficiencies due to the diversion of compressed air for thermal management systems, which wastes energy and interrupts the propulsive engines' thermodynamic cycle, increasing weight and complexity.
Innovation Solution
Mechanically coupling a gas turbine engine shaft to a reverse Brayton cycle via a gearbox to provide mechanical energy, allowing the cycle to operate independently of engine thrust settings and reducing thermodynamic losses.
Engineering Contradictions & Design Principles
Engineering 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 energy is wasted and the thermodynamic cycle of the propulsive engines is interrupted
Solution Approach 1:
The patent extracts the thermal management power source from the propulsive engine's compressed air supply. Instead of diverting compressed air from the engines, a separate auxiliary power unit (APU) is introduced to independently power the reverse Brayton cycle, thereby eliminating energy waste and preserving the propulsive engines' thermodynamic cycle integrity
Solution Approach 2:
The patent segments the aircraft power system into separate functional units: propulsive engines for thrust generation and an auxiliary power unit for thermal management. This segmentation allows each system to operate independently without interfering with the other, resolving the contradiction between thermal management operation and energy efficiency
2Reliability
If pressure regulators and heat exchangers are added to cool compressed air before it reaches the reverse Brayton cycle, then the system can function, but weight and complexity increase
Solution Approach 1:
The patent removes the need for complex air cooling infrastructure by extracting the power source from the propulsive engines entirely. The APU generates power independently, eliminating the requirement for pressure regulators and heat exchangers that would otherwise be needed to condition compressed air from the main engines
Solution Approach 2:
The auxiliary power unit serves as an intermediary between the aircraft's power needs and the thermal management system. Rather than directly using compressed air from the propulsive engines, the APU mediates by converting fuel into mechanical power that drives the reverse Brayton cycle, simplifying the overall system architecture
3Power
If compressed air is diverted from the propulsive engines, then the reverse Brayton cycle can be powered, but the efficiency of the propulsive engines is reduced
Solution Approach 1:
The patent divides the power generation function into two separate systems: propulsive engines dedicated to thrust and an auxiliary power unit dedicated to electrical and mechanical power for aircraft systems. This segmentation ensures that energy extraction for thermal management does not compromise propulsive engine efficiency
Solution Approach 2:
The patent extracts the power generation function from the propulsive engines and assigns it to a separate auxiliary power unit. This extraction allows the propulsive engines to operate at optimal efficiency for thrust generation while the APU independently provides power for the reverse Brayton cycle and other aircraft systems
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 thermodynamic inefficiencies, allowing the thermal management system to operate optimally without disrupting the propulsive engines.
Implementation Method 1
Mechanically coupling a gas turbine engine shaft to a reverse Brayton cycle via a gearbox to provide mechanical energy
Implementation Method 2
a reverse Brayton cycle system (RBC) that is pneumatically driven by compressed air
Data Source
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 heat 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.