Waveguide Antenna for Microwave Combustion Enhancement
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Solution Overview
Problem
Existing combustion systems face challenges in enhancing combustion efficiency, stability, and reducing emissions, particularly in achieving leaner mixtures and tolerating increased exhaust gas recirculation, where microwave energy is typically used for ignition rather than enhancement.
Innovation Solution
An elongated waveguide antenna with a ceramic core and metallic shell, offering high thermal conductivity, is positioned in the combustor to emit microwave energy within the frequency range of 7.0 GHz to 9.0 GHz, enhancing combustion once ignition is achieved, while preventing heat storage and supporting high pressures and temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If microwave energy is used for ignition, then ignition capability is improved, but combustion enhancement after ignition is insufficient
Solution Approach 1:
The patent applies preliminary action by providing ignition through a separate ignition source (spark plug or other ignition device) before the waveguide antenna is activated. The waveguide antenna then continues to emit microwave energy after ignition has occurred, serving to enhance combustion rather than initiate it. This sequential approach ensures reliable ignition first, then combustion enhancement, resolving the contradiction between ignition capability and post-ignition combustion enhancement.
2Productivity
If microwave energy is continuously emitted, then combustion enhancement is improved, but heat storage in the antenna increases
Solution Approach 1:
The patent introduces a waveguide antenna as an intermediary structure that transmits microwave energy from the microwave source to the combustion chamber. The waveguide antenna is designed with specific material properties (low dielectric loss, high thermal conductivity) to efficiently conduct microwave energy while managing heat dissipation. This intermediary structure enables continuous microwave emission for combustion enhancement without excessive heat accumulation in the antenna itself.
Solution Approach 2:
The patent applies parameter changes by selecting specific material properties for the waveguide antenna, including low dielectric loss and high thermal conductivity. These parameter changes allow the antenna to efficiently transmit microwave energy while dissipating heat effectively, enabling continuous operation for combustion enhancement without dangerous heat accumulation.
3Productivity
If high power microwave energy is used, then combustion enhancement is improved, but device complexity increases
Solution Approach 1:
The waveguide antenna serves multiple functions: it transmits microwave energy from the source, focuses the energy into the combustion chamber, and manages heat dissipation through its material properties. This multi-functional design consolidates several requirements into a single component, reducing overall system complexity while maintaining high power capability for combustion enhancement.
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 solution improves flame speed, combustion stability, thermal efficiency, and reduces emissions by efficiently using microwave energy to accelerate combustion chemical reactions throughout the combustion cycle, making it suitable for various engine types including diesel and gasoline engines.
Implementation Method 1
An elongated waveguide antenna is positioned in the combustor wherein the antenna is connected to a microwave power source and wherein the waveguide antenna indicates a thermal conductivity of at least 150 W/m−K. The antenna emits microwave energy that does not ignite the combustible mixture but is sufficient to enhance combustion once ignition is achieved.
Implementation Method 2
utilizes microwave energy from the waveguide antenna to enhance combustion of the previously ignited mixture
Implementation Method 3
An elongated waveguide antenna with a ceramic core and metallic shell, offering high thermal conductivity, is positioned in the combustor to emit microwave energy within the frequency range of 7.0 GHz to 9.0 GHz, enhancing combustion once ignition is achieved, while preventing heat storage and supporting high pressures and temperatures.
Data Source
AI summary
The present invention is directed at a waveguide antenna for microwave enhanced combustion of a previously ignited fuel-air mixture. The waveguide antenna has a thermal conductivity of at least 150 W/m−k and can be formed from a metallic shell with a ceramic core.