Particle exhaust sensor for a solid fuel-burning appliance and solid fuel-burning appliance including same
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Solution Overview
Problem
Existing optical particle sensors for monitoring smoke particles in solid fuel-burning appliances are not suitable for residential or light-commercial settings due to high costs, complexity, and maintenance requirements, and lack accuracy in detecting smoke composition and concentration efficiently.
Innovation Solution
A sensor apparatus using 'backwards' light scattering with light sources and detectors mounted on the same side of the duct, emitting light at specific wavelengths, and a processor to determine smoke particle concentration, which can also estimate water vapor to particle ratios and adjust for temperature variations, facilitating improved combustion control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If industrial optical systems based on transmissive or forward light scattering are used, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent inverts the conventional optical detection approach by using backscatter detection instead of transmissive or forward scatter detection. The light source and detector are positioned on the same side of the duct, detecting light scattered back from particles in the exhaust stream. This inversion simplifies the optical system architecture while maintaining measurement capability for smoke particle concentration and composition.
Solution Approach 2:
The patent combines the light source and detector into a single housing unit mounted on the same side of the exhaust duct. This merging of components reduces the overall system complexity and eliminates the need for communication cables crossing high-temperature zones, while still enabling accurate smoke particle detection through backscatter measurement.
2Measurement precision
If industrial optical systems are used, then measurement precision is improved, but ease of operation deteriorates
Solution Approach 1:
By inverting the detection geometry to use backscatter rather than transmissive measurement, the patent eliminates the need for the optical path to cross the high-temperature exhaust zone. The light source and detector remain in the ambient temperature environment, simplifying installation and maintenance while preserving measurement accuracy.
Solution Approach 2:
The patent uses backscattered light as an intermediary measurement approach. Instead of requiring the optical components to directly interface with the hot exhaust stream (as in transmissive measurement), the system detects light that has scattered back from particles, allowing measurement without direct exposure to harsh conditions.
3Measurement precision
If multiple light sources at different wavelengths are used, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent employs multiple light sources operating at different wavelengths (e.g., UV, visible, infrared) to probe different aspects of smoke particle composition. By varying the wavelength parameter, the system can estimate the ratio of water vapor to other smoke particles, improving compositional analysis while managing complexity through modular light source selection.
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 provides accurate, cost-effective, and simplified monitoring of smoke particles, enabling faster detection and improved control of combustion conditions, while reducing maintenance complexity and avoiding high-temperature zone issues.
Implementation Method 1
optical sensors and detection methods disclosed herein may be generally characterized as using 'backwards' light scattering as a basis for determining a concentration of smoke particles in an exhaust gas stream
Implementation Method 2
optical sensors and detection methods disclosed herein may emit and/or detect light at specified frequency or wavelength ranges. This may improve the accuracy of smoke particle detection.
Implementation Method 3
The detected light signal comprises at least one of a reflected portion of the first and second light signals and a diffracted portion of the first and second light signals
Data Source
AI summary
Exhaust sensors for use with residential solid fuel-burning appliances are disclosed. In one example, a sensor apparatus includes an optical sensor, a lens, and first and second light sources positioned adjacent to the optical sensor. The first light source is configured to emit a first light signal towards a target area of an exhaust gas stream. The second light source is configured to emit a second light signal towards the target area. The optical sensor is configured to detect a light signal comprising at least one of a reflected portion of the first and second light signals and a diffracted portion of the first and second light signals. The sensor apparatus also includes a processor configured to determine a concentration of smoke particles in the exhaust gas stream based on the detected light signal.