Optimization of Nozzle Configuration in an Evaporative Condensation Growth Scrubber for Enhanced PM2.5 Capture

Upper Northern Thailand continues to face a protracted structural crisis from fine-particulate matter (PM2.5), primarily driven by biomass burning and wildfires. Conventional mechanical capture systems, such as cyclones, often suffer a drastic efficiency drop when treating sub-micron particles. This study introduces an innovative Evaporative Condensation Growth Scrubber (ECGS) designed to bridge this technological gap by promoting the growth of fine particles through heterogeneous nucleation. Experimental testing across 10 different nozzle configurations was conducted to optimize the system’s performance. The results revealed that the ECGS system significantly outperformed the dry cyclone (Baseline) across all nine testing configurations. While the Baseline showed inherent limitations in capturing sub-micron particles, the ECGS demonstrated relative efficiency improvements ranging from 39.53% to 83.23% for PM2.5, and 26.10% to 61.50% for PM10 compared to the baseline. Optimal performance was achieved using a 90-degree injection angle and a 10 cm distance, which created a complete spray curtain and maximized collision probability. Under these conditions, the outlet PM2.5 concentration stabilized at 11.81 µg/m3 within 180 s of water injection. Crucially, despite sensor interference caused by high relative humidity, the system’s effectiveness was confirmed by a significant difference in performance in PM10 and PM2.5 removal. The PM10 collection efficiency outperformed that of PM2.5 by 28.82%, providing empirical evidence that PM2.5 particles successfully acted as nuclei for condensation and grew into the larger PM10 size range. This particle growth enabled more effective centrifugal separation, demonstrating that the ECGS system offers a viable and efficient solution for fine particle removal in highly polluted environments.