Multi-Pulse Laser Igniter for High-Pressure sCO2 Mixtures
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Solution Overview
Problem
Existing ignition systems for supercritical carbon dioxide (sCO2) combustors face challenges in igniting highly diluted and pressurized fuel-oxidizer mixtures, particularly at high pressures (above 50 bar), as spark plugs foul, fail to light, or flame out, and hypergolic chemicals are toxic and difficult to handle.
Innovation Solution
A laser-based ignition system using multi-pulse lasers with variable focal lengths is employed to selectively ignite fuel-oxidizer mixtures in specific regions of the combustion chamber, improving ignition probability and adaptability to varying pressures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If spark plugs are used for ignition in high pressure sCO2 combustors, then ignition can be achieved at lower pressures, but the spark plugs foul, fail to light, or flame out at pressures above 50 bar
Solution Approach 1:
The patent replaces the mechanical spark plug ignition system with a laser-based ignition system. The laser beam focuses energy directly onto the fuel-oxidizer mixture, creating a plasma kernel that initiates combustion without mechanical contact. This substitution eliminates the fouling and failure issues inherent in spark plugs operating in high-pressure sCO2 environments.
Solution Approach 2:
The patent changes the ignition mechanism from electrical discharge (spark plugs) to optical energy concentration (laser). By using a laser with adjustable parameters (power, pulse duration, focal length), the system can reliably ignite the fuel mixture across a wide pressure range from atmospheric to 300 bar, adapting to different operating conditions without mechanical wear or fouling.
2Reliability
If hypergolic chemicals are used for ignition, then ignition can be achieved at high pressures, but the chemicals are toxic and difficult to handle
Solution Approach 1:
The patent replaces chemical ignition methods (hypergolic chemicals) with a physical ignition method (laser). The laser beam delivers energy non-contactly to the fuel-oxidizer mixture, eliminating the need for toxic hypergolic chemicals and their associated handling, storage, and safety issues while maintaining reliable ignition capability at high pressures.
Solution Approach 2:
The laser beam acts as an intermediary that transfers energy from the power source to the fuel-oxidizer mixture without requiring direct contact with toxic chemicals. This intermediary approach enables ignition while avoiding the harmful factors associated with hypergolic chemicals.
3Stress or pressure
If the spark gap is decreased to enable ignition at high pressures, then ignition voltage requirement is reduced, but the electrodes interfere with energy transfer from the spark kernel to the surrounding combustible gas mixture
Solution Approach 1:
The patent replaces the electrode-based spark gap system with a laser-based energy delivery system. The laser beam focuses energy directly into the fuel-oxidizer mixture without physical electrodes, eliminating the interference problem where electrodes would block or scatter the spark kernel energy. This enables efficient energy transfer across the entire combustion chamber volume.
Solution Approach 2:
The patent transitions from a one-dimensional spark gap (between two electrodes) to a volumetric laser focus. The laser can be focused to a precise point or distributed across a volume within the combustion chamber, enabling energy deposition in three-dimensional space without the geometric constraints of electrode spacing and orientation.
4Adaptability or versatility
If multi-pulse lasers with variable focal lengths are used, then ignition probability and adaptability to varying pressures are improved, but device complexity increases
Solution Approach 1:
The patent incorporates a dynamically adjustable laser focal length mechanism that can be controlled in real-time. This allows the system to adapt to different combustion chamber pressures and geometries by changing the focal point position, maintaining optimal ignition performance across varying operating conditions without requiring multiple fixed-focus laser systems.
Solution Approach 2:
The patent designs a single laser system that performs multiple functions: it can operate in single-pulse or multi-pulse modes, adjust its focal length to match different pressure conditions, and target different locations within the combustion chamber. This multi-functional approach consolidates what would otherwise require multiple specialized ignition devices into one versatile system.
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 efficient ignition with high efficiency (above 40%) and minimal emissions, allowing quick restarts and non-perturbation of combustor flow fields, suitable for pressures ranging from 4 bar to 300 bar.
Implementation Method 1
contacting the mixture with a laser, whereby the laser is pointed to a predetermined point within the chamber
Implementation Method 2
the laser is pointed to a predetermined point within the chamber for a first period of time
Data Source
AI summary
The invention provides method for igniting pressurized fuel, the method comprising placing fuel into a combustion chamber; mixing the fuel with supercritical carbon dioxide and oxidizer to create a mixture; and contacting the fuel-air mixture with a laser, whereby the laser is pointed to a first point within the chamber. Also provided is a laser ignitor for carbon dioxide combustors, the ignitor comprising: an elongated housing capable of varying in length, the housing having a first proximal end and a second distal end; a laser head in close spatial relationship to the proximal end, wherein the laser head generates a first laser beam; a seal at the distal end that is optically transparent to the laser beam and physically opaque to combustion contaminants; an algorithm for directing the first beam to a first point within a combustion chamber for a first period of time; and an algorithm for directing a second laser beam to a second point within the combustion chamber for a second period of time.