PM2.5 Mass Concentration Calculation via Number Density and Humidity
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Solution Overview
Problem
Current methods for measuring PM2.5 concentration, such as filter trapping and beta attenuation, are either time-consuming, expensive, or lack precision, making it difficult to install numerous measurement stations for real-time data collection, and existing number concentration methods have low conversion accuracy to mass concentration.
Innovation Solution
A calculation device that uses a function defining the relationship between mass and number concentrations of PM2.5 particles and humidity to accurately calculate mass concentration in one location based on measurements from another location, employing a combination of mass concentration detectors and number concentration detectors with hygrometers to improve precision and reduce costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If filter trapping or beta attenuation measurement is used to measure mass concentration, then measurement precision is improved, but device complexity and cost increase, making it difficult to install numerous measurement stations
Solution Approach 1:
The patent uses number concentration measurement data as a substitute or copy for mass concentration measurement. Instead of deploying expensive mass concentration measurement devices everywhere, the system copies the functional capability by using readily available number concentration data combined with environmental parameters (temperature, humidity, pressure) to estimate mass concentration through calculated relationships, thereby achieving widespread deployment while maintaining measurement capability
Solution Approach 2:
The patent introduces environmental parameters (temperature, humidity, pressure) as intermediary variables that mediate between number concentration and mass concentration. These intermediaries allow the system to bridge the gap between the easily measurable number concentration and the desired mass concentration without requiring direct mass concentration measurement equipment at every station
2Measurement precision
If filter trapping method is used, then mass concentration can be measured, but measurement time increases and real-time data collection becomes difficult
Solution Approach 1:
The patent replaces the mechanical filter trapping process with an optical/electronic measurement system. Instead of physically collecting particles on a filter over time, the system uses light scattering detection to measure number concentration in real-time, then substitutes the time-consuming mechanical filtration process with rapid optical measurement combined with computational estimation of mass concentration
3Device complexity
If number concentration measurement is used, then device cost is reduced and numerous stations can be installed, but conversion accuracy to mass concentration decreases
Solution Approach 1:
The patent changes the parameters used for mass concentration estimation from a simple constant conversion factor to a dynamic model that incorporates multiple environmental parameters (temperature, humidity, pressure). By changing from a static conversion approach to a multi-parameter dynamic model, the system maintains measurement precision while using simpler number concentration measurement devices
Solution Approach 2:
The patent creates a composite measurement approach by combining number concentration data with environmental parameter data (temperature, humidity, pressure). This composite methodology integrates multiple data sources to achieve accurate mass concentration estimation without requiring expensive dedicated mass concentration measurement equipment
Data Source
AI summary
A calculation device includes: an acquisition unit that obtains a mass concentration of particles in a gas measured in a first measurement station, a number concentration of particles in the gas measured in a second measurement station, and a humidity of the gas measured in the second measurement station; and a calculation unit that calculates a function, which defines a relationship of a mass concentration and a number concentration to a humidity and is used to calculate a mass concentration of particles in the gas in a third measurement station from a number concentration of particles in the gas and a humidity of the gas measured in the third measurement station, based on the mass concentration in the first measurement station and the number concentration and the humidity in the second measurement station, the third measurement station being installed in a different location from the first and second measurement stations.