Aircraft Bleed Air Conditioning with Heat Recovery
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Solution Overview
Problem
Aircraft bleed air systems generate waste heat that is typically exhausted without utilization, limiting the efficiency of the environmental control systems (ECS) and increasing fuel costs.
Innovation Solution
A method and system utilizing a turbo air cycle machine with a turbo-ejector and controllable valves to precondition bleed air from gas turbine engines, combining low and high pressure air streams to meet the demand of the ECS while recovering energy, thereby reducing waste heat.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a pre-cooler heat exchanger is used to precondition hot bleed air from engines, then the bleed air temperature is reduced to sustainable levels for ECS, but waste heat is exhausted without utilization reducing system efficiency
Solution Approach 1:
The patent converts the harmful waste heat from the pre-cooler into a useful resource by routing it through a heat recovery heat exchanger that pre-heats the ambient air intake for the ECS. This transforms the thermal energy that would otherwise be discarded into a beneficial contribution toward meeting the ECS heating demand, thereby reducing the energy penalty associated with bleed air conditioning.
2Ease of operation
If bleed air is extracted from engines to power ECS, then environmental control is achieved, but engine efficiency is reduced and fuel consumption increases
Solution Approach 1:
The patent merges the engine bleed air system with the ECS ambient air intake system through a heat recovery heat exchanger. By combining these previously separate air streams and enabling thermal energy transfer between them, the system reduces the total bleed air required from the engine while still meeting ECS heating demands, thereby improving engine efficiency and reducing fuel consumption.
3Quantity of substance
If bleed air pressure is increased to meet ECS demand, then sufficient airflow is provided, but system complexity and energy losses increase
Solution Approach 1:
The patent employs dynamically controllable isolation valves that can adjust or close off bleed air pathways based on real-time system demands. This dynamic control allows the system to optimize bleed air pressure and flow rate, providing sufficient airflow to the ECS only when necessary while minimizing energy losses through unnecessary high-pressure bleed extraction during periods when lower pressure or reduced flow suffices.
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 bleed air conditioning efficiency, reduces fuel costs, and extends the aircraft's operational range by utilizing excess heat and providing variable bleed air conditioning to match dynamic ECS demands.
Implementation Method 1
The pre-cooler heat exchangers produce waste heat, which is typically exhausted from the aircraft without utilization
Implementation Method 2
A method and system utilizing a turbo air cycle machine with a turbo-ejector and controllable valves to precondition bleed air from gas turbine engines, combining low and high pressure air streams
Data Source
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AI summary
A method and aircraft for providing bleed air to environmental control systems of an aircraft using a gas turbine engine, including determining a bleed air demand for the environmental control systems, supplying low pressure and high pressure bleed air to the environmental control systems, wherein the proportional supplying is controlled such that the conditioned air stream meets the determined bleed air demand.