Aircraft Environmental Control System Ejector Bleed Air Reduction
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Solution Overview
Problem
Aircraft environmental control systems (ECS) face inefficiencies in energy consumption and weight due to high requirements for bleed air conditioning, which consumes non-propulsive power and increases emissions, necessitating a reduction in bleed air usage while maintaining cabin pressure and comfort.
Innovation Solution
The ECS incorporates an ejector to draw ambient air, mixing it with bleed air to create a low-pressure area, reducing the need for bleed air and utilizing exhaust air to power a turbine for further efficiency, with a heat exchanger system that includes a primary heat exchanger and compressor to condition the air effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If bleed air is used to provide pressurised and conditioned air to the aircraft cabin, then cabin pressure and comfort are maintained, but energy consumption and emissions increase
Solution Approach 1:
The patent merges the functions of multiple heat exchangers into a single integrated unit where hot bleed air and cold RAM air flow through alternating channels, allowing simultaneous heating and cooling operations to occur in one compact device, thereby reducing overall system energy consumption
Solution Approach 2:
The patent introduces a secondary fluid loop as an intermediary between the heat exchangers and the cabin air conditioning system. This secondary loop allows thermal energy to be transferred and redistributed more efficiently, reducing the direct energy demand on bleed air
2Temperature
If bleed air is conditioned through multiple heat exchangers, then appropriate temperature and pressure are achieved, but device complexity and weight increase
Solution Approach 1:
The patent combines multiple heat exchanger functions into a single integrated heat exchanger assembly with interconnected first and second heat exchangers, reducing the number of separate components, connections, and control systems required, thereby simplifying the overall device structure and reducing weight
Solution Approach 2:
The integrated heat exchanger serves multiple functions simultaneously: it conditions hot bleed air, cools using RAM air, and manages thermal energy distribution through a secondary fluid loop, allowing one component to perform what previously required multiple separate devices
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 reduces bleed air consumption, lowers fuel burn, recovers waste exhaust air energy, and enhances energy efficiency and environmental sustainability of the ECS.
Implementation Method 1
an ejector arranged to receive bleed air from the bleed air input at a nozzle shaped to reduce the pressure of the received bleed air such as to create a low pressure area in the ejector
Implementation Method 2
create a low pressure area in the ejector, the ejector having a port arranged such that ambient air is drawn into the ejector due to the low pressure area
Implementation Method 3
heat exchanger means for receiving bleed air from the bleed air input and RAM air from the RAM air input and using the RAM air to cool the bleed air
Implementation Method 4
The incoming air is, however, at a relatively high temperature and pressure and needs to be conditioned to the appropriate temperature and pressure before it is fed into the cabin. The way this is usually done is to use ambient air, brought into the system via an air intake device, such as a scoop. This air—so-called RAM air—is used in a system of heat exchangers to cool the bleed air
Implementation Method 5
the mixed air leaving the ejector is compressed by a compressor
Implementation Method 6
the compressor is powered by a turbine extracting power from conditioned air exhausted from the aircraft cabin
Data Source
AI summary
An aircraft environmental control system includes a bleed air input and a RAM air input, heat exchanger means for receiving bleed air from the bleed air input and RAM air from the RAM air input and using the RAM air to cool the bleed air, and ejector arranged to receive bleed air from the bleed air input at a nozzle shaped to reduce the pressure of the received bleed air such as to create a low pressure area in the ejector. The ejector has a port arranged such that ambient air is drawn into the ejector due to the low pressure area in the ejector. The ambient air is mixed with bleed air to provide mixed air that is further pressurised and conditioned and combined with the cooled bleed air provided to the aircraft.