Blended flow air cycle system for environmental control
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Solution Overview
Problem
Aircraft environmental control systems waste energy by throttling down high-pressure bleed air to meet cabin air distribution requirements, leading to increased fuel burn and inefficiency, despite attempts to improve energy efficiency through 'more-electric' approaches which add weight, cost, and complexity.
Innovation Solution
An aircraft air provision system that utilizes a power turbine to generate rotational energy from bleed air, couples a compressor to drive air to an intermediate pressure, and incorporates a mix chamber and cooling turbine to combine bleed and ram air streams at identical pressures, leveraging excess pressure to drive a turbocompressor and optimize energy use.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stress or pressure
If high-pressure bleed air is throttled down to meet cabin air distribution requirements, then the air pressure is adjusted to suitable levels, but energy is wasted and fuel burn increases
Solution Approach 1:
A turbocompressor acts as an intermediary device that receives high-pressure bleed air and delivers it to the cabin air distribution system at the required lower pressure, avoiding direct throttling and the associated energy losses
Solution Approach 2:
The mechanical throttling process is replaced with a turbocompressor system that uses the pressure differential to drive a turbine-compressor mechanism, converting the pressure energy into useful work rather than dissipating it as waste
2Loss of energy
If a turbocompressor is used to deliver bleed air at suitable pressure, then energy efficiency is improved, but device complexity increases
Solution Approach 1:
The turbocompressor serves multiple functions: it acts as a pressure regulator, an energy recovery device, and a delivery mechanism, consolidating several functions into a single component to reduce overall system complexity
Solution Approach 2:
The turbocompressor utilizes the existing pressure differential of the bleed air system to drive itself, requiring no external power source and integrating seamlessly with the existing engine airflow
3Use of energy by moving object
If more-electric approaches are used to improve energy efficiency, then energy utilization is optimized, but weight, cost and complexity increase
Solution Approach 1:
The system uses pneumatic principles by utilizing the pressurized bleed air itself to drive the turbocompressor, eliminating the need for electrical motors, generators, and associated control systems that would add weight and complexity
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 fuel economy by reducing bleed air requirements, minimizing component size, eliminating the need for engine bleed pressure regulation, and simplifying systems, while providing conditioned air for cabin and flight deck.
Implementation Method 1
a power turbine that receives bleed air at a first pressure and provides rotational energy to a shaft
Implementation Method 2
a compressor coupled to the shaft that receives input air at a second pressure that is lower than the first pressure and outputs compressed air having a pressure equal to the intermediate pressure
Implementation Method 3
a precooling heat exchanger in fluid communication with an input of the power turbine and configured to cool air exiting the compressor section, wherein the preceding heat exchanger utilizes air from a fan of the engine to cool air exiting the compressor section
Implementation Method 4
a mix chamber coupled to outputs of both the power turbine and the compressor where the output air and the compressed air are mixed
Implementation Method 5
a cooling turbine coupled to the shaft that is in fluid communication with an output of the mix chamber
Data Source
Figure 1
Figure 2
AI summary
An aircraft air provision system (102) includes a power turbine (132) that receives bleed air at a first pressure and provides rotational energy to a shaft (134) and outputs output air at an intermediate pressure. The system also includes a compressor (135) coupled to the shaft (134) that receives input air at a second pressure that is lower than the first pressure and outputs compressed air having a pressure equal to the intermediate pressure and a mix chamber (142) coupled to outputs of both the power turbine (132) and the compressor (135) where the output air and the compressed air are mixed. The system also includes a cooling turbine (136) coupled to the shaft (134) and that is in fluid communication with an output of the mix chamber (142).