Optimization of fibrous air filter on the basis of particle condensational growth during the air cooling and de-humidification process using mathematical modeling

Abstract

Indoor ultra-fine particles have significantly adverse effects on human health. Under the condition of high concentration, the widely used HEPA (High-Efficiency Particulate Air) requires expensive operation cost. Previous study indicated that air cooling and dehumidification system could greatly increase particle size (from dozens of nanometers to several micrometers) due to the condensation effect during the process of air conditioning in hot and humid regions. Because of the condensational growth of particles, low-grade air filters can be used to achieve high efficiency and lower cost. This study developed mathematical model to predict particle size variation in cooling and dehumidification process and investigate its effect on fibrous filter performance. The steps are as follows: 1) Based on the state-space model, distributions of supersaturation ratio in condensational dehumidification process were simulated; 2) The modified Lagrangian method and SSR-based model were used to simulate particle trajectory and size increase; 3) Based on the prediction of condensational growth of particles, the air filter performance model were adopted to investigate the condensation effect on fibrous filter performance. The results shows that condensational dehumidification improve the filtration efficiency of middle-efficiency fibrous from 72% to 92%, quality factor from 0.016 to 0.031. Utilization of condensational dehumidification could decrease energy consumption of fibrous filtration system by 53%. This study is of great significance to improve the effectiveness and economy through the coordinated control for indoor pollutants, temperature and humidity control in humid and hot climate region.