Hydrogen Venturi Array for Subsonic Fuel-Cell Recirculation
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Solution Overview
Problem
Conventional hydrogen fuel-cell systems face challenges in efficiently recirculating hydrogen gas across varying operating conditions, particularly during take-off and cruise phases, due to the limitations of fixed venturi geometry, which can lead to subsonic flow requirements and icing issues, while existing battery-powered aircraft are impractical for long-range flights.
Innovation Solution
A hydrogen fuel-cell system with a plurality of venturis and controlled valves to manage hydrogen gas flow subsonically, optimizing recirculation across different flight phases, and a digital controller for selective valve operation, along with a hydrogen gas recirculation system incorporating a water separator.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a single fixed geometry venturi is used for hydrogen recirculation, then the device complexity is reduced, but the system cannot maintain optimal subsonic flow across varying operating conditions (take-off vs. cruise)
Solution Approach 1:
The single venturi is segmented into multiple venturis with different geometries. Each venturi is sized to handle specific flow rate ranges, allowing the system to maintain optimal subsonic flow conditions across varying operating conditions from take-off to cruise.
Solution Approach 2:
The system transitions from a fixed geometry venturi to a dynamic configuration where multiple venturis can be selectively activated. This allows the recirculation system to adapt its flow characteristics dynamically based on operating conditions while maintaining subsonic flow regime.
2Productivity
If venturi geometry is optimized for maximum flow rate, then productivity is improved, but subsonic flow requirement cannot be maintained at lower flow rates
Solution Approach 1:
By dividing the recirculation system into multiple venturis of different sizes, each venturi can be optimized for specific flow rate ranges. This segmentation allows the system to maintain subsonic flow conditions across the entire operating range from maximum take-off flow to lower cruise flow rates.
Solution Approach 2:
The system changes the geometric parameters of the venturis by selecting different venturis from the array based on operating conditions. This parameter change allows optimization of flow rate for productivity while maintaining subsonic flow regime for reliability.
3Loss of energy
If recirculation suction is increased to improve hydrogen utilization, then energy efficiency is improved, but the risk of ice crystal formation and blockages increases
Solution Approach 1:
By changing the venturi geometry parameters (selecting different venturis from the array), the system can adjust the suction characteristics to match operating conditions. This allows maximizing hydrogen recirculation efficiency while maintaining flow velocities that prevent ice crystal formation and blockages.
4Device complexity
If a single venturi is sized for cruise conditions, then device complexity is reduced, but turn-down in suction during take-off is significantly reduced
Solution Approach 1:
Instead of a single venturi sized for cruise, the system segments the recirculation capability into multiple venturis. This allows the system to provide high suction capability during take-off by activating appropriate venturis while maintaining simpler overall device architecture.
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
Enhances hydrogen recirculation efficiency and prevents icing, ensuring optimal hydrogen flow across varying flight conditions, thereby improving the performance and safety of hydrogen fuel-cell systems in aircraft.
Implementation Method 1
Venturis are widely used passive devices that utilize restriction within the flow path to vary the flow characteristics of a fluid. As the geometry increases the fluid's velocity, there is a corresponding drop in pressure. This negative pressure can then be used to draw a secondary fluid into the primary flow.
Implementation Method 2
one or more valves configured to selectively open and close to control flow of the hydrogen gas through the venturis to a speed below the speed of sound, i.e., subsonic, and above the speed where venturi icing occurs
Implementation Method 3
a water separator upstream of the recirculating hydrogen gas
Data Source
AI summary
An integrated hydrogen-electric engine includes a hydrogen fuel-cell; a hydrogen fuel source; an electric motor assembly disposed in electrical communication with the fuel-cell; an air compressor system configured to be driven by the motor assembly, and a cooling system having a heat exchanger radiator in a duct of the cooling system, and configured to direct an air stream including an air stream from the air compressor through the radiator, wherein an exhaust stream from a cathode side of the fuel-cell is fed via a flow control nozzle into the air stream in the cooling duct downstream of the radiator.