Aircraft ECS Pack Using Cabin Air to Drive ACM Compression
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Solution Overview
Problem
The existing gas turbine engine compressor systems experience efficiency reduction and increased weight due to bleeding off compressed air for non-propulsive purposes, such as cabin pressurization and de-icing, which requires cooling and does not generate thrust, leading to reduced compressor efficiency and additional weight from heat exchangers.
Innovation Solution
An environmental control system (ECS) pack with a primary and secondary heat exchanger, an air cycle machine, and operational modes selected based on flight conditions and bleed air pressure, optimizing air supply to the cabin while minimizing pressure differences and reducing bleed-related penalties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If compressed bleed air is diverted from the primary flow path to the bleed air system, then cabin pressurization and de-icing functions are provided, but compressor efficiency is reduced and thrust is decreased
Solution Approach 1:
The patent converts the harmful effect of hot bleed air into a beneficial cooling effect by using it in a heat exchanger to cool the cabin air cycle machine air, thereby providing cabin pressurization and de-icing functions while minimizing the efficiency penalty to the compressor
Solution Approach 2:
The system changes the temperature parameter of the bleed air by cooling it in a heat exchanger before using it in the air cycle machine, transforming it from hot high-pressure air into cooler air suitable for cabin pressurization and de-icing operations
2Temperature
If a heat exchanger is used to cool the bleed air, then the bleed air temperature is reduced for cabin use, but the heat exchanger increases system weight and occupies space
Solution Approach 1:
The heat exchanger is designed to serve multiple functions: cooling the bleed air for cabin pressurization, providing cooling air for the air cycle machine, and potentially serving as a pre-cooler for the compressor inlet air, thereby reducing the need for separate cooling systems and minimizing overall weight
Solution Approach 2:
The patent merges the cooling function for the air cycle machine with the bleed air cooling function by using the same heat exchanger for both purposes, thereby reducing the total number of components and system weight while achieving the required temperature reduction
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 ECS pack optimizes the operation of the gas turbine engine by reducing the pressure difference between bleed air and cabin air, enhancing fuel efficiency and reducing the overall weight and space requirements of the bleed air system.
Implementation Method 1
a compressor compresses air and passes that air along a primary flow path
Implementation Method 2
a heat exchanger is used to cool the bleed air
Implementation Method 3
The combusted mixture expands and is passed to a turbine, which is forced to rotate due to the passing combusted mixture
Data Source
AI summary
An environmental control system (ECS) pack is provided including a primary heat exchanger and a secondary heat exchanger. An air cycle machine is arranged in fluid communication with at least one of the primary and second heat exchanger. The air cycle machine includes a compressor and a plurality of turbines. Discharged cabin air is supplied to at least one of the plurality of turbines to operate the compressor.