Sheath Airflow Deflection for Beta Attenuation Particle Accuracy
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing particulate mass measuring devices, particularly those using beta attenuation, suffer from inaccurate measurements due to particulate matter of sizes 10 microns or less becoming stuck on the surfaces of the airflow chamber, leading to particulate loss and anomalous readings.
Innovation Solution
Incorporating a sheath air plenum and radial sheath airflow pathway that merges with the axial airflow to deflect particulate matter from curved surfaces, ensuring that particles are directed to the filter tape for accurate mass measurements, thereby enhancing the accuracy of particulate mass concentration calculations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If ambient air enters the ambient airflow chamber through the inlet, then the particulate matter can be collected on the filter tape, but larger particles having greater inertial force hit the curved or bent surfaces of the nozzle and become stuck, resulting in inaccurate measurement
Solution Approach 1:
A radial sheath airflow pathway is introduced as an intermediary element that merges with the axial ambient airflow pathway. This sheath airflow acts as a mediator to deflect particulate matter away from curved surfaces and guide it toward the filter tape, preventing particle loss while maintaining measurement accuracy
Solution Approach 2:
The invention uses pneumatic flow (radial sheath airflow) to control particle trajectory. By introducing this additional airflow pathway, particles are pneumatically guided along a modified trajectory that avoids impaction on curved surfaces and ensures they reach the filter tape for accurate measurement
2Reliability
If the axial ambient airflow pathway is used to transport particles to the filter tape, then mass concentration can be measured, but particles may accumulate on chamber surfaces and dislodge randomly causing anomalous measurements
Solution Approach 1:
The radial sheath airflow serves as a protective intermediary layer between the ambient air and the curved chamber surfaces. This sheath flow prevents particles from contacting and accumulating on surfaces that could later cause measurement anomalies, thereby improving both reliability and precision
Solution Approach 2:
The sheath airflow performs a preliminary action by deflecting particles away from curved surfaces before they can accumulate. This preventive measure eliminates the source of future measurement anomalies, ensuring consistent and reliable measurements over time
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 solution increases the accuracy of particulate mass measurements by preventing particulate matter from being retained on chamber surfaces, reducing maintenance needs and providing reliable data by ensuring all relevant particles are accounted for in the measurement process.
Implementation Method 1
a radial sheath airflow pathway that merges with the axial ambient airflow pathway to deflect ambient airflow particulate matter from curved or bent surfaces
Implementation Method 2
The filter tape collects the particulate matter present within the ambient air over time... As the amount of particulate matter collected by the filter tape increases, the particulate matter attenuates the beta radiation emitted from the beta radiation source
Data Source
AI summary
A particulate mass measuring device of the beta attenuation type featuring a sheath air plenum from which a radial sheath airflow pathway extends which is in fluid communication with an ambient air chamber. The radial sheath airflow from the radial sheath airflow pathway merges with an axial ambient airflow from the ambient air chamber deflecting particulate matter from surfaces of the ambient air chamber thereby increasing the accuracy of particulate mass measurements. The radial sheath airflow is particle free or substantially particle free. In other embodiments, the radial sheath airflow is used to deflect particulate matter in other particulate mass measuring devices, such as those that measure particulate mass in liquid and gas samples.