Particulate Matter Sensor Sheath Flow for Optical Stability
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Solution Overview
Problem
Existing particulate matter sensors suffer from long-term stability issues due to particulate contamination of radiation detectors and sources, leading to measurement inaccuracies and reduced lifespan.
Innovation Solution
A particulate matter sensor device with a flow modifying device that sheaths the radiation detector and source, reducing particulate precipitation by modifying the aerosol flow upstream, using additional flows to divert particles away from sensitive components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional optical sensor design is used, then the device structure is simple, but particulate matter precipitates on the radiation detector and source, leading to sensor deterioration and reduced measurement accuracy
Solution Approach 1:
The flow channel is divided into distinct regions: a measurement region for optical detection and a sheath flow region for particle diversion. The sheath flow channel is segmented with multiple openings that create localized flow zones around the radiation detector and source, separating the particle-laden aerosol flow from the sensitive optical components.
Solution Approach 2:
A sheath flow of clean gas is introduced as an intermediary medium between the aerosol sample and the radiation detector/source. This sheath flow acts as a protective barrier that redirects particulate matter away from the optical components while allowing the measurement of aerosol properties to continue uninterrupted.
2Reliability
If additional flow openings are added to modify the aerosol flow, then particulate matter precipitation is reduced, but the device complexity increases
Solution Approach 1:
The invention uses pneumatic principles by introducing a sheath flow of clean gas through multiple openings in the flow channel walls. This gas flow creates pressure differentials and flow patterns that naturally divert particulate matter away from the radiation detector and source without requiring mechanical moving parts or complex control systems.
Solution Approach 2:
The flow velocity, direction, and density parameters of the aerosol sample are locally modified by the sheath flow introduction. By changing these flow parameters in the region around the radiation detector and source, the system reduces particle precipitation while maintaining the overall flow structure and measurement capabilities.
3Measurement precision
If the aerosol flow velocity is increased to prevent particle deposition, then measurement accuracy is maintained, but more particulate matter precipitates on the radiation detector and source
Solution Approach 1:
The sheath flow is introduced locally at specific positions around the radiation detector and source, creating zones of modified flow characteristics only where needed. This local modification diverts particles away from sensitive areas while maintaining the overall aerosol flow velocity and measurement conditions in the detection region.
Solution Approach 2:
The sheath flow openings are arranged in multiple dimensions around the radiation detector and source, creating a three-dimensional flow modification pattern. This multi-dimensional approach to flow control effectively surrounds and protects the optical components from particle deposition while maintaining measurement accuracy.
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
Enhances sensor longevity and accuracy by minimizing particulate deposition, ensuring stable and precise measurements over time.
Implementation Method 1
configured to at least locally modify the flow of the aerosol sample, preferably the flow velocity of the aerosol sample, the direction of the aerosol sample, and/or the aerosol density
Implementation Method 2
a radiation source (3) arranged and configured to emit radiation at least partially into the flow channel (2) for interaction of the radiation with at least some of the particulate matter
Implementation Method 3
a radiation detector (4) arranged and configured to detect at least part of the radiation that has interacted with the particulate matter
Data Source
Figure 1(a)~2(c)
Figure 3~5
Figure 6(a)~6(b)
AI summary
A particulate matter sensor device comprises an enclosure (21) defining a flow channel (2) between a primary flow inlet (11) and a flow outlet (12), a radiation source (3) for emitting radiation into the flow channel for interaction of the radiation with particulate matter in an aerosol sample in the flow channel, and a radiation detector (4) for detecting at least part of said radiation after interaction with the particulate matter. An additional flow opening (511, 511a, 512, 513, 514) creates an additional flow into the flow channel. The additional flow opening is arranged in a wall section that radially delimits the flow channel upstream of the radiation detector and/or of the radiation source and being configured to create its additional flow so that the additional flow sheaths the radiation detector and/or the radiation source.