Particle Detection Bypass Flow Pressure Gradient
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Solution Overview
Problem
Conventional particle detection systems face accuracy degradation due to particles escaping the fluid flow between the inlet and outlet nozzles, leading to spurious optical emissions and particle deposition on the sensing chamber walls, which are difficult to dislodge.
Innovation Solution
The system pressurizes the sensing chamber to create a uniform high-to-low pressure gradient by introducing a bypass flow of filtered air, which is regulated and introduced remotely from the interrogation zone, ensuring all particles are evacuated and preventing backflow or escape.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional particle detection systems use inlet and outlet nozzles to draw fluid through a sensing chamber, then particles can be detected in the interrogation zone, but particles may escape the fluid flow and enter the sensing chamber, creating spurious optical emissions and degrading measurement accuracy
Solution Approach 1:
A bypass flow of filtered air is introduced as an intermediary substance into the sensing chamber. This bypass flow acts as a mediator that displaces unfiltered sample air and prevents particles from escaping the main fluid flow, thereby eliminating spurious optical emissions while maintaining accurate particle detection in the interrogation zone
Solution Approach 2:
The system changes the pressure parameter within the sensing chamber by introducing bypass flow at a controlled rate. This pressure change creates a uniform high-to-low pressure gradient that ensures orderly fluid flow through the interrogation zone and prevents particle escape, resolving the accuracy degradation problem
2Productivity
If conventional systems rely on suction pressure to draw fluid through the sensing chamber, then particles can be evacuated through the outlet nozzle, but particles may back up against the flow and enter the sensing chamber through the outlet nozzle
Solution Approach 1:
The bypass flow is introduced as a preliminary protective measure before particle backflow can occur. By establishing a positive pressure environment in the sensing chamber through bypass flow, the system creates a counteracting force that prevents particles from backing up against the main fluid flow and entering through the outlet nozzle
Solution Approach 2:
The bypass flow serves as an intermediary that separates the suction pressure effect from the particle flow path. It mediates between the outlet nozzle suction and the interrogation zone, ensuring that particles are evacuated efficiently without backing up into the sensing chamber
3Measurement precision
If particles escape the fluid flow and deposit on the sensing chamber walls, then measurement accuracy is maintained, but the deposited particles are difficult to dislodge and can cause ongoing contamination
Solution Approach 1:
The bypass flow, which could be seen as an additional complexity, actually converts the harmful effect of particle deposition into a benefit by creating a protective pressure environment. This pressure gradient prevents particles from reaching the chamber walls in the first place, eliminating the cleaning and maintenance problem 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
This approach eliminates the need for additional pumps, reduces particle escape, and allows for higher throughput while maintaining accurate measurement data, as demonstrated by computational fluid dynamics modeling and experimental results.
Implementation Method 1
The system pressurizes the sensing chamber to create a uniform high-to-low pressure gradient by introducing a bypass flow of filtered air
Implementation Method 2
containing particles to be measured within a laminar gas flow within a sensing chamber
Implementation Method 3
measuring the amount and directionality of light scattered by particles to determine particle size
Implementation Method 4
the measurement of fluorescence excited in particles by illumination with a source light to classify measured particles as biological or non-biological
Data Source
AI summary
A particle detection system is provided, including a sensing chamber having an inlet nozzle, an outlet nozzle, and an interrogation zone defined therebetween. Particles in a sampled environmental gas are prevented from escaping the interrogation zone by pressurizing the sensing chamber such that the pressure therein is higher than that in the outlet nozzle. This is accomplished by providing a source of extra gas to the sensing chamber, for example, by diverting gas from an inlet flow path directly to the sensing chamber.