Light-Scattering Fine Dust Measurement with Humidity Control
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Solution Overview
Problem
Conventional light scattering particulate matter measuring apparatuses face inaccuracies in measuring fine particulate matter due to relative humidity, static electricity, and particulate matter adherence, especially when used outdoors.
Innovation Solution
A light scattering particulate matter measuring apparatus with a heater to control relative humidity, an antistatic layer to prevent particulate matter adherence, and insulation layers to maintain temperature, combined with temperature and humidity sensors for accurate measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional light scattering particulate matter measuring apparatus is used, then the measurement can be performed in real time at low cost, but the measurement accuracy deteriorates when relative humidity is high due to water vapor condensation on hygroscopic particulate matter surfaces
Solution Approach 1:
The heater is positioned upstream of the particulate matter sensor in the airflow passage, performing preliminary heating of the air before it reaches the sensor. This preliminary action prevents water vapor condensation on hygroscopic particles by maintaining elevated temperature throughout the airflow path, thereby preserving measurement accuracy under high humidity conditions
2Measurement precision
If a heater is added to control relative humidity, then measurement accuracy improves, but device complexity and size increase
Solution Approach 1:
The heater is integrated directly into the airflow passage structure, merging the heating function with the existing air intake channel. This integration eliminates the need for separate heating chambers or complex humidity control systems, thereby improving measurement accuracy while minimizing increases in device complexity and size
3Ease of operation
If the inlet is arranged at the uppermost portion to introduce ambient air, then air introduction is simplified, but particulate matter adheres to the inlet by static electricity causing measurement errors
Solution Approach 1:
The heater performs a dual function: it heats the air to prevent water vapor condensation for accurate measurement, and simultaneously generates thermal energy that reduces static electricity accumulation on the inlet and airflow passage surfaces. This converts the harmful static electricity effect into a beneficial thermal effect, preventing particle adhesion 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
The apparatus achieves accurate particulate matter concentration measurement by controlling humidity and minimizing static electricity effects, ensuring reliable and precise results.
Implementation Method 1
a heater disposed on the airflow passage near the inlet
Implementation Method 2
a light scattering particulate matter sensor disposed on the airflow passage between the heater and the outlet to measure particulate matter concentration of the measurement air
Implementation Method 3
an internal temperature-humidity sensor disposed on the airflow passage between the heater and the light scattering particulate matter sensor to measure temperature and relative humidity of the measurement air
Implementation Method 4
the particulate matter contained in the air introduced through the inlet adheres to the inlet by static electricity
Data Source
AI summary
A light scattering particulate matter measuring apparatus is disclosed. The light scattering particulate matter measuring apparatus according to the present invention comprises: a casing provided with an inlet into which outside air flows and an outlet through which is exhausted measured air of which the particulate matter concentration has been measured; an airflow pathway which connects the inlet and the outlet in the casing and along which outside air moves; and an external temperature-humidity sensor which is provided on the outside of the casing and measures the temperature and relative humidity of outside air.