Microwave Sensor for Combustible Gas Air Ratio
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Solution Overview
Problem
Existing sensors for determining the air ratio of combustible gas/air mixtures, such as lambda (λ) sensors, face limitations in efficiency, response time, and power consumption, and require adaptation to specific gas burners.
Innovation Solution
A sensor that induces an exothermic chemical reaction in a combustible gas/air mixture using a microwave field, measured by an optical sensing device, allowing for real-time air ratio calculation with low electrical power consumption and no need for adaptation to gas burners, utilizing a micro-strip line to generate a standing wave for efficient energy delivery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a microwave field is used to induce exothermic chemical reactions in the reaction position, then the response time is reduced and measurement speed is improved, but the device complexity increases due to the need for microwave generation components
Solution Approach 1:
The patent combines multiple functions into the micro-strip line structure: it serves as both the microwave field generator and the energy delivery mechanism to induce chemical reactions. This integration reduces the number of separate components needed while achieving fast response times through microwave-induced exothermic reactions in the measurement space.
2Measurement precision
If electrochemical measuring cells are used for air ratio determination, then the measurement capability is provided, but the adaptation to specific gas burners is required and efficiency is limited
Solution Approach 1:
The patent creates a universal sensor design that can measure air ratios for different combustible gas types without requiring adaptation to specific gas burners. The microwave-induced chemical reaction approach and optical detection method provide a general-purpose measurement capability that works across various gas compositions, eliminating the need for burner-specific calibration or configuration.
3Measurement precision
If conventional sensors are used for air ratio determination, then the measurement function is provided, but the power consumption is high and sensor lifetime is reduced due to heat transfer to electrodes
Solution Approach 1:
The patent replaces the conventional electrochemical measurement system with a microwave-optical system. Instead of using electrodes that generate heat and consume continuous electrical power, the system uses microwave fields to induce chemical reactions and optical detection to measure the results. This substitution significantly reduces electrical power consumption while extending sensor lifetime by eliminating the heat transfer problem associated with continuous electrode operation.
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
Enables fast and accurate measurement of air ratios in combustible gas/air mixtures with low power consumption and extended sensor lifetime, suitable for various gas types without the need for parameterization, and can be directly integrated into gas mixing systems.
Implementation Method 1
a microwave field is provided in the reaction position such that, in the reaction position, an exothermic chemical reaction is induced by the microwave field in the combustible gas/air mixture
Implementation Method 2
an exothermic chemical reaction is induced by the microwave field in the combustible gas/air mixture. These reactions are releasing light and heat
Implementation Method 3
the optical sensing device senses the intensity of radiation from the reaction position in at least one wavelength range and generates a signal assigned to the sensed intensity
Implementation Method 4
utilizing a micro-strip line to generate a standing wave for efficient energy delivery
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
Sensor (3) for determining an air ratio of a combustible gas/air mixture, the sensor comprising: a housing (4) which limits a measuring space (5), a gas permeable separation means (6), an electrically operated stimulating means (9) for an energy supply into the measuring space (5) in order to bring about a chemical reaction of the gas/air mixture in the measuring space (5), a voltage supply (13) coupled with the stimulating means (9), an optical sensing device (15). The stimulating means (9) is adapted to effect the energy supply at a reaction position (12) situated in the measuring space (5), wherein the stimulating means (9) is formed by constructively and galvanically separated excitation electrodes (10, 11) which protrude at least partially into the measuring space (5), wherein the reaction position lies (12) between the electrodes (10, 11). The optical sensing device (15) is directed in the measuring space (5) onto the reaction position (12), wherein the optical sensing device (15) senses the intensity of radiation from the reaction position (12) and generates a signal assigned to the sensed intensity, from which the air ratio can be calculated. The voltage supply (13) is coupled with the excitation electrodes (10, 11) in such a way that a microwave field is provided in the reaction position (12) such that, in the reaction position (12), an exothermic chemical reaction is induced by the microwave field in the gas/air mixture.