Gas Burner Flame Ionization Control to Avoid Harmonic Noise Modes
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Solution Overview
Problem
Existing gas burners, particularly those used in vehicles, often operate in a harmonic mode that produces disturbing noise due to sound frequencies of 1400-1800 hertz and amplitudes greater than 55 decibels, which is particularly problematic when used at night.
Innovation Solution
A gas burner system with a variable-speed forced-air device and a controller that measures flame ionization current to maintain a minimum fan speed and air-fuel equivalence ratio, avoiding the harmonic mode by actively controlling the air-gas mixture to ensure a Reynolds number greater than 1000 and an equivalence ratio of greater than 1.2.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the gas burner operates with standard air-fuel mixing, then the burner can function normally, but it produces disturbing noise due to harmonic modes at 1400-1800 hertz with amplitudes greater than 55 decibels
Solution Approach 1:
The patent applies parameter changes by modifying the air-fuel equivalence ratio to be greater than 1.2 and maintaining the Reynolds number greater than 1000 through variable fan speed control. These parameter adjustments shift the combustion characteristics to avoid the harmonic resonance frequencies of 1400-1800 hertz, thereby eliminating the disturbing noise while preserving normal burner operation
Solution Approach 2:
The patent implements feedback control by using a flame sensor to continuously monitor the combustion process and adjust the fan speed accordingly. The controller receives signals from the flame sensor and dynamically modifies the air supply to maintain the equivalence ratio above 1.2 and Reynolds number above 1000, preventing the system from entering the harmful harmonic mode frequency range
2Object-affected harmful factors
If the fan speed is reduced to lower noise, then noise level decreases, but the burner enters harmonic mode and produces disturbing sounds at 1400-1800 hertz
Solution Approach 1:
The patent resolves this contradiction by changing the operational parameters specifically the equivalence ratio to greater than 1.2 and Reynolds number to greater than 1000. By maintaining these parameter thresholds through variable fan speed control, the system avoids the harmonic resonance conditions that produce disturbing sounds, achieving noise reduction without entering harmful operational modes
Solution Approach 2:
The patent applies dynamics by implementing a variable-speed fan controlled by a controller that adjusts operational parameters in real-time. The fan speed is dynamically modified based on combustion conditions to maintain the equivalence ratio above 1.2 and Reynolds number above 1000, preventing the system from settling into static harmonic modes while minimizing noise
3Object-affected harmful factors
If the air-fuel mixture is not precisely controlled, then the system is simpler to operate, but it cannot maintain the Reynolds number greater than 1000 and equivalence ratio greater than 1.2 to avoid harmonic modes
Solution Approach 1:
The patent employs feedback control where a flame sensor continuously monitors combustion parameters and the controller adjusts the fan speed accordingly. This closed-loop system automatically maintains the equivalence ratio greater than 1.2 and Reynolds number greater than 1000, eliminating harmonic mode noise while managing control complexity through automated parameter adjustment based on real-time combustion conditions
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
Significantly reduces or eliminates the undesirable noise associated with harmonic mode by maintaining optimal air-fuel ratios and fan speeds, ensuring quiet operation and compliance with emission standards.
Implementation Method 1
an electrode configured to ignite the air-gas mixture so as to produce a flame. The electrode is further configured to measure a flame ionization current associated with the flame
Implementation Method 2
a variable-speed forced-air device, such as a fan, that forces air through the conduit
Implementation Method 3
a gas burner with a conduit into which an air-gas mixture is conducted
Data Source
Figure 1
Figure 2~3
Figure 4
AI summary
A gas burner system (12) has a gas burner with a conduit (16) through which an air-gas mixture is conducted; a variable-speed forced-air device (40) that forces air through the conduit (16); a control valve (44) that controls a supply of gas for mixture with the air to thereby form the air-gas mixture; and an electrode (30) configured to ignite the air-gas mixture so as to produce a flame (29). The electrode is further configured to measure a flame ionization current associated with the flame (29). A controller (50) is configured to actively control the variable-speed forced-air device based on the flame ionization current measured by the electrode (30) so as to automatically avoid a flame harmonic mode of the gas burner (10). Corresponding methods are provided.