Cryogenic Engine Bleed Air Cooling for Aircraft Liquid Air Separation
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Solution Overview
Problem
Current aircraft systems face inefficiencies in propulsion, thermal management, and power generation due to constraints on gas turbine engine design, air intake, and fuel supply, limiting the effectiveness of gas turbine engines and electric propulsion motors.
Innovation Solution
A cryogenic cooling system is integrated with a gas turbine engine to chill engine bleed air, producing liquid air and separating gaseous nitrogen and liquid oxygen for on-board use, which can be utilized for cooling, propulsion, and fuel system inerting, enhancing thermodynamic efficiency and power density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If gas turbine engines are designed with material property constraints, then structural integrity is maintained, but thermodynamic efficiency deteriorates due to work losses in cooling air branches
Solution Approach 1:
The patent changes the temperature parameter of the cooling air branch by introducing a cryogenic heat exchanger that cools the air to very low temperatures (cryogenic range). This parameter change allows the cooling air to provide useful refrigeration work while still maintaining structural integrity, effectively converting what was previously a waste energy stream into a useful resource.
Solution Approach 2:
The patent utilizes phase transitions of air components (particularly nitrogen and oxygen) by cooling the air to cryogenic temperatures where these gases can liquefy or form two-phase mixtures. This phase transition enables the extraction of maximum refrigeration effect while the condensed phases can be separated and used for various aircraft systems, reducing the overall energy loss.
2Productivity
If liquid air is produced through cryogenic cooling, then chilled working fluid is generated for aircraft use, but system complexity increases due to vacuum and condensate pump requirements
Solution Approach 1:
The patent makes the cryogenic cooling system multi-functional by producing liquid air that serves multiple purposes: refrigeration for aircraft systems, source of separated oxygen for combustion enhancement, source of separated nitrogen for fuel system inerting, and potential propulsion assistance. This universality justifies the added system complexity as a single system replaces or supplements multiple separate systems.
Solution Approach 2:
The system utilizes the natural vacuum environment of space (external atmosphere) as the heat sink for the cryogenic heat exchanger, eliminating the need for complex refrigerant circulation systems. The air is directly cooled by transferring heat to the external environment, and the condensed components separate naturally based on their physical properties, reducing the need for complex pumping and separation equipment.
3Temperature
If engine bleed air is used for cooling, then thermal management is achieved, but propulsion efficiency deteriorates due to pressure and temperature constraints
Solution Approach 1:
The patent applies preliminary cooling action by pre-cooling the engine bleed air in a cryogenic heat exchanger before it enters the aircraft systems. This preliminary action at cryogenic temperatures provides maximum refrigeration effect with minimum energy input, as the temperature differential is maximized. The pre-cooled air then requires less additional cooling to reach operational temperatures, improving overall energy efficiency.
Solution Approach 2:
The patent replaces the conventional thermal management system that relies on mechanical compression and moderate temperature differential heat exchangers with a cryogenic system that uses extreme temperature differentials. This substitution allows for more efficient heat transfer and refrigeration with less mechanical work, as the large temperature gradient enables passive or minimal-work cooling processes.
4Adaptability or versatility
If gaseous nitrogen and liquid oxygen are separated from liquid air, then isolated sources are provided for aircraft systems, but separation process complexity increases
Solution Approach 1:
The patent utilizes the different phase transition temperatures of nitrogen and oxygen to achieve separation. By controlling the temperature of the liquid air in the separation chamber, nitrogen (with lower boiling point) vaporizes first while oxygen remains liquid, or vice versa depending on the desired separation sequence. This natural phase transition-based separation eliminates the need for complex membrane or distillation systems.
Solution Approach 2:
The separation process leverages the inherent physical properties of nitrogen and oxygen (different boiling points, densities, and phase transition characteristics) to achieve automatic separation without external intervention. The components separate themselves based on their thermodynamic properties when exposed to controlled temperature and pressure conditions, minimizing the need for active separation equipment.
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 provides efficient chilled working fluid generation and separation, improving aircraft performance by enhancing propulsion, reducing fuel consumption, and increasing power density, while also providing isolated sources of oxygen and nitrogen for various aircraft systems.
Implementation Method 1
a heat exchanger system operable to pre-cool the engine bleed air flow
Implementation Method 2
a compressor operable to further compress the engine bleed air flow as compressed air
Implementation Method 3
at least one turbine operable to expand and cool the compressed air as a cooled flow
Implementation Method 4
a vacuum system and a condensate pump system operable to condense the liquid air from the cooled flow
Implementation Method 5
a cryogenic air separator operable to separate gaseous nitrogen from the liquid air as a gaseous nitrogen supply and separate liquid oxygen from the liquid air as a liquid oxygen supply
Data Source
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AI summary
A system for an aircraft (100) includes an engine bleed source (251) of a gas turbine engine (20). The system also includes a means for chilling an engine bleed air flow (252) from the engine bleed source (251) to produce a chilled working fluid. The system further includes a means for providing the chilled working fluid for an aircraft use.