Optimization of a dust concentration measuring device based on the Coanda effect

The accuracy of the existing dust measurement device comprising a straight pipe is not sufficiently high for low particle speeds. In this paper, a measuring pipe based on the Coanda effect is designed, an experimental model is established using Gambit 2.4, and a numerical simulation is performed using Fluent 6.3. In this way, speed nephograms at the middle section of the device pipe were obtained for different dust particle sizes. By comparing the velocity data of a devices comprising a straight tube, a venturi tube, or a Coanda tube, it was found that the velocity of the particles passing through the Coanda tube was higher than that for the other tubes. Therefore, the probability of frictional collision within the Coanda tube increases, thereby increasing the inductive charge of the particles. By calculating the electrostatic induction of the particles using MATLAB, it was found that the charge carried by the particles in the improved device significantly increased (25% on average). It is concluded that these findings are of significance for designing the structure of novel dust concentration measurement devices.

Effect of Atmospheric Humidity on Fine Dust Measurement Using the Light Scattering Method

The interest in fine dust has greatly increased. Therefore, sensors and devices for measuring the concentration of fine dust have been developed and are being used. For example, the distribution of light scattering measuring sensors has increased the use of self-measurement to manufacture and measure fine dust detectors. However, fine dust detectors that use light scattering are extremely sensitive to humidity; there is a highly sensitive component that recognizes water vapor in the air as fine dust. Therefore, the purpose of this study is to quantitatively understand the influence of atmospheric humidity on the concentration of fine dust and to use this understanding to correct measured values. In this study, we investigated the correlation between fine dust concentration and relative humidity measured by a fine dust sensor using the light scattering method. As a result, relative humidity and fine dust concentration exhibited a high positive correlation. The same trend was also observed when the humidity either increased or decreased.

Reliability of Low-Cost, Sensor-Based Fine Dust Measurement Devices for Monitoring Atmospheric Particulate Matter Concentrations

Currently, low-cost, sensor-based fine dust measurement devices are commercially available in South Korea. This study evaluated the reliability of three such devices—Yi Shan A4, Plantower PMS7003, and Plantower PMS7003—in comparison to long-term consecutive monitoring systems for discharge and prevention facilities regarding fine dust control. The performance of these devices for concentration intervals over time was examined through real-time comparison using a GRIMM (Model: 11-A, dust spectrometer from Grimm Technologies) as a reference; this included a correction factor (C-Factor), calculated by a gravimetric method and an equivalence test. For comparison, the reference and target devices were installed in a chamber with fine dust concentrations of 2 µg/m3, with temperature and humidity maintained at 20 °C and 40%, respectively. The fine particulate matter (PM)2.5 concentrations were classified into five intervals: ≤40 µg/m3, 40–80 µg/m3, 80–120 µg/m3, 120–160 µg/m3, and 200–230 µg/m3. Statistical analysis was performed using data obtained from national stations for monitoring and controlling fine dust released from facilities under high fine dust loading conditions. The results showed that the measurements of all target devices, which were corrected according to the reference device, provided accurate values at PM2.5 concentrations of ≥40 µg/m3. The statistical analysis results suggest that the evaluated devices are more reliable than the conventional numerical-analysis-based monitoring system