Calibrated Aerosol Source for Constant Particle Size Distribution
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Solution Overview
Problem
Existing devices for calibrating aerosol photometers struggle to maintain constant particle size distribution (PSD) at lower aerosol concentrations, leading to inaccurate measurements.
Innovation Solution
A calibrated aerosol source (CAS) system that includes aerosol generators, primary and secondary mixing chambers, and features such as liquid flow control, pressure controllers, and back pressure plates to maintain constant PSD across various concentration ranges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If mechanical diluters are used to reduce aerosol concentration, then lower concentration calibration is achieved, but particle size distribution changes
Solution Approach 1:
The patent extracts the aerosol generation function from mechanical diluters and places it in a controlled aerosol source that generates aerosol directly at the desired concentration without dilution, thereby maintaining particle size distribution while achieving lower concentrations
Solution Approach 2:
The patent changes the operating parameters of the aerosol generation system, specifically controlling temperature, pressure, and flow rates to maintain constant particle size distribution while varying aerosol concentration through controlled evaporation and mixing processes
2Adaptability or versatility
If aerosol concentration is reduced to verify linearity at lower concentrations, then calibration range is expanded, but particle size distribution is altered
Solution Approach 1:
The controlled aerosol source is designed to universally generate aerosol at any concentration within a wide range while maintaining constant particle size distribution, making it applicable for calibrating photometers across multiple concentration points without changing PSD
Solution Approach 2:
The patent introduces an intermediary evaporation chamber where aerosol is generated through controlled evaporation of liquid aerosol precursor, allowing concentration adjustment without mechanical dilution that would alter particle size distribution
3Measurement precision
If gravimetric measurement is used for calibration, then absolute concentration accuracy is achieved, but particle size distribution must be maintained constant
Solution Approach 1:
The patent incorporates feedback control through sensors that monitor aerosol concentration and particle size distribution, automatically adjusting operating parameters to maintain constant PSD while achieving accurate concentration control for gravimetric calibration
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 CAS system effectively generates aerosols with constant PSD across a wide range of concentrations, ensuring accurate calibration and testing of aerosol photometers without altering the PSD.
Implementation Method 1
two Laskin nozzles, each comprising a tube with a single opening formed in a sidewall of the tube and a single opening formed in a collar of the Laskin nozzle
Implementation Method 2
providing a back pressure plate in the one or mixing chambers to have a plurality of openings in a grid configuration and operating a fan at a specific rate to ensure the desired positive pressure in a given mixing chamber
Implementation Method 3
operating a fan at a specific rate to ensure the desired positive pressure in a given mixing chamber
Implementation Method 4
maintaining the oil level (e.g., PAO or DOP) of one or more aerosol generators at a particular height (e.g., at a particular height above a portion of a Laskin nozzle or atomizer or any other suitable aerosol generating component)
Data Source
AI summary
A calibrated aerosol source (“CAS”) and related methods for parameterizing, testing, troubleshooting and/or calibrating an instrument (e.g., photometers) or a system. Preferably, the CAS allows for generation of multiple concentrations while maintaining constant particle size distribution (PSD) for all aerosol concentrations, so that the aerosol response at other points in a particular range can be verified and linearity that was previously assumed can be proved.