Hydrogen Fuel Preheater Baffle Layout for Gas Turbine Engines
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Solution Overview
Problem
The use of hydrogen as a fuel in gas turbine engines requires pre-heating to prevent icing and enable combustion, but existing pre-heating methods reduce engine efficiency and cause hot spots, damage to heat exchangers, and thermoacoustic oscillations due to non-uniform gas velocity and flame propagation.
Innovation Solution
A fuel system with baffles and a heat exchanger configuration that promotes turbulence and uniform gas flow, using inlet and outlet baffles to manage airflow and prevent flame propagation, combined with an auxiliary heater and ignitor to control combustion, ensuring efficient and compact pre-heating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the heat exchanger is positioned close to the burner to achieve compact design, then the pre-heater volume is reduced, but hot spots occur in the burner exhaust gases causing damage to the heat exchanger
Solution Approach 1:
An outlet baffle is introduced as an intermediary component between the burner and heat exchanger. This baffle promotes turbulence and mixing of exhaust gases, preventing hot spots while allowing the heat exchanger to remain close to the burner for compact design.
Solution Approach 2:
The outlet baffle creates local variations in flow characteristics and temperature distribution by inducing turbulence. This ensures more uniform heat distribution across the heat exchanger surface, preventing localized overheating and damage.
2Volume of moving object
If the heat exchanger is positioned close to the burner to achieve compact design, then the pre-heater volume is reduced, but heat exchange efficiency decreases due to non-uniform gas velocity profile
Solution Approach 1:
The outlet baffle acts as a flow conditioning intermediary that transforms the non-uniform velocity profile from the burner into a more uniform distribution at the heat exchanger inlet, maintaining high heat exchange efficiency in a compact configuration.
Solution Approach 2:
The outlet baffle dynamically conditions the exhaust gas flow by creating turbulence and mixing, which enhances heat transfer coefficients and improves overall heat exchange efficiency despite the reduced distance between burner and heat exchanger.
3Reliability
If large spacing is provided between burner and heat exchanger to prevent flame transmission, then heat exchanger damage is avoided, but the pre-heater volume increases
Solution Approach 1:
The outlet baffle serves as a flame arrestor intermediary, blocking flame propagation from the burner to the heat exchanger while maintaining sufficient thermal contact for efficient heat transfer, thus preventing the need for large spacing.
Solution Approach 2:
The baffle creates localized flow patterns that prevent flame transmission through the gap between burner and heat exchanger, allowing the system to maintain compact dimensions while ensuring heat exchanger protection.
4Productivity
If turbulence is introduced to improve mixing and heat exchange, then heat exchange efficiency increases, but pressure drop increases
Solution Approach 1:
The outlet baffle introduces a controlled amount of turbulence - sufficient to improve mixing and heat exchange efficiency, but not excessive to cause unacceptable pressure drop. The baffle geometry is optimized to achieve the minimum necessary turbulence for effective heat transfer.
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 achieves high heat exchange efficiency, prevents heat exchanger damage, and damps thermoacoustic vibrations, resulting in improved component life and reduced engine specific fuel consumption.
Implementation Method 1
a heat exchanger configured to transfer heat from exhaust gasses produced by the burner to fuel in the main fuel conduit
Implementation Method 2
at least one outlet baffle positioned between the burner and the heat exchanger configured to introduce turbulence to combustion gases entering the heat exchanger
Implementation Method 3
a burner configured to burn the portion of hydrogen fuel diverted from the main fuel conduit
Implementation Method 4
The through-holes may be sized to prevent flame transmission through the baffle
Data Source
AI summary
A fuel system for a gas turbine engine comprises a fuel offtake configured and arranged to divert a portion of hydrogen fuel from a main fuel conduit, a burner configured and arranged to burn the portion of hydrogen fuel diverted from the main fuel conduit, a heat exchanger configured and arranged to transfer heat from exhaust gasses produced by the burner to hydrogen fuel in the main fuel conduit, and an outlet baffle positioned between the burner and the heat exchanger. The outlet baffle is configured to introduce turbulence to combustion gases entering the heat exchanger.