Publication date: 1 February 2017
Source:Building and Environment, Volume 112
Author(s): Juwon Pyo, Yoohyun Ock, Dongkyo Jeong, Kihong Park, Donggeun Lee
The public health impact of particulate matter in ambient air with a size of 2.5 μm or smaller (PM2.5 ) has been of great concern. It is well known that PM2.5 is much more harmful to human health than coarse particles. To remove PM2.5 , most air purifiers on the market have been equipped with a high efficiency particulate air (HEPA) filter. Under the circumstances that generate PM2.5 aerosols at high concentrations such as during indoor cooking or in work places, HEPA-grade filters are neither durable nor applicable because of their high replacement cost. Thus, a large number of cooks and workers are exposed to intensive emissions of PM2.5 without proper filtration. In this paper, we introduce a novel concept to remove PM2.5 without HEPA filters. A key idea is to use the condensational growth of particles. Once the particles have grown to a few micron, they are much easier to remove because of their increased inertia. Based on this, we developed the first prototype of a filter-free particle filtration unit consisting of an air saturator (equipped with water spray nozzles), a condenser in which humid air is cooled down to a supersaturation state and thereby allows particles to grow by condensation, and a multi-nozzle-impactor assembly for collecting the grown particles downstream of the condenser. We started with a small-scale model, and then demonstrated that a large-scale prototype could remove organic, inorganic, and metallic ultrafine particles with a collection efficiency of larger than 80% at a volume flow rate of 50–92 L/s.
Source:Building and Environment, Volume 112
Author(s): Juwon Pyo, Yoohyun Ock, Dongkyo Jeong, Kihong Park, Donggeun Lee