Jet Engine Bleed Air Cooling System with Separate Flow Paths
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Solution Overview
Problem
Conventional jet engine bleed air cooling systems are unable to deliver air at temperatures lower than the lowest temperature air flowing through the engine, limiting the effectiveness of thermal management and environmental control systems in aircraft.
Innovation Solution
A cold air cooling system that includes a precooler, a heat exchanger, a compressor, and a turbine in separate flow paths, with a bypass line for selective fluid communication, allowing for the cooling of bleed air to temperatures below the engine's mean flow path temperature, and a discharge conduit to manage the cooled air for aircraft thermal management and environmental control systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If conventional bleed air cooling systems are used, then the system structure is simple, but the cooling temperature cannot go below the lowest temperature air flowing through the engine
Solution Approach 1:
The cooling system is divided into separate flow paths: a first flow path for bleed air through a precooler, and a second flow path for cooling air through a compressor and second precooler. This segmentation allows independent optimization of each path to achieve sub-ambient temperatures while managing system complexity through modular design.
Solution Approach 2:
The invention nests multiple cooling stages within each other: the bleed air cooling system is nested within the engine air flow, with the compressor drawing from the first flow path and the second precooler utilizing the compressed air. This nested arrangement allows achieving lower temperatures by combining multiple cooling effects in a compact configuration.
2Temperature
If bleed air is regulated from HPC using flow control valves, then the pressure is controlled, but the airflow is restricted and temperature cannot be reduced below engine flow path temperature
Solution Approach 1:
The system performs preliminary cooling of the bleed air in the first precooler before the air enters the compressor. This preliminary action reduces the temperature of the air that will be compressed, allowing the final cooled air to reach temperatures below the engine's mean flow path temperature while maintaining adequate airflow rates.
Solution Approach 2:
The invention introduces an intermediary cooling path using the compressor and second precooler as mediators. The compressor draws air from the first flow path and delivers it to the second precooler, which acts as an intermediary heat exchanger to further cool the bleed air. This intermediary mechanism enables temperature reduction below what a single precooler could achieve while maintaining airflow productivity.
3Loss of energy
If a single precooler is used, then the system is simple, but the thermal load reduction is insufficient
Solution Approach 1:
The invention merges two separate cooling paths into a unified system: the first precooler handling bleed air cooling and the second precooler handling compressed air cooling. These two heat exchangers work in combination, with the second precooler utilizing the compressed air from the first path as its cooling medium, thereby achieving greater thermal load reduction than either heat exchanger could provide alone.
Solution Approach 2:
The system changes the parameters of the cooling air through compression, increasing its pressure and temperature in the compressor. This parameter change allows the compressed air to serve as an effective cooling medium in the second precooler, enabling the system to achieve lower final temperatures and greater thermal load reduction by operating at different pressure and temperature stages.
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 system effectively cools bleed air to temperatures below the engine's mean flow path temperature, reducing thermal loads and enhancing the efficiency of aircraft thermal management and environmental control systems, providing a significant reduction in thermal load, typically by more than 10% or up to 90 kW.
Implementation Method 1
a first precooler in fluid communication with the bleed air from the jet engine compressor
Implementation Method 2
a heat exchanger in fluid communication with and downstream from the first precooler
Implementation Method 3
a cooling system compressor in fluid communication with and downstream from the first precooler
Implementation Method 4
a cooling system turbine in fluid communication with and downstream from the cooling system precooler
Data Source
AI summary
Methods and devices for cooling systems (700) are provided that are in fluid communication with bleed air from a jet engine compressor. The cooling system can include: a first precooler (210) receiving bleed air from the jet engine compressor; a heat exchanger (730) downstream from the first precooler (210); a cooling system compressor (220) downstream from the first precooler (210), wherein the heat exchanger (730) and the cooling system compressor (220) are in separate flow paths from the first precooler (210); a cooling system precooler (230) downstream from the cooling system compressor (220); a VGT cooling system turbine (240) downstream from the cooling system precooler (230); and a discharge conduit (245) downstream from the cooling system turbine (240) and the heat exchanger (730). A bypass line (290) for bypassing the turbine can also be included.