Effectiveness of Photocatalytic Filter for Removing Volatile Organic Compounds in the Heating, Ventilation, and Air Conditioning System

Abstract

Nowadays, the heating, ventilation, and air conditioning (HVAC) system has been an important facility for maintaining indoor air quality. However, the primary function of typical HVAC systems is to control the temperature and humidity of the supply air. Most indoor air pollutants, such as volatile organic compounds (VOCs), cannot be removed by typical HVAC systems. Thus, some air handling units for removing VOCs should be added in typical HVAC systems. Among all of the air cleaning techniques used to remove indoor VOCs, photocatalytic oxidation is an attractive alternative technique for indoor air purification and deodorization. The objective of this research is to investigate the VOC removal efficiency of the photocatalytic filter in a HVAC system. Toluene and formaldehyde were chosen as the target pollutants. The experiments were conducted in a stainless steel chamber equipped with a simplified HVAC system. A mechanical filter coated with Degussa P25 titania photocatalyst and two commercial photocatalytic filters were used as the photocatalytic filters in this simplified HVAC system. The total air change rates were controlled at 0.5, 0.75, 1, 1.25, and 1.5 hr Ϫ1 , and the relative humidity (RH) was controlled at 30%, 50%, and 70%. The ultraviolet lamp used was a 4-W, ultraviolet-C (central wavelength at 254 nm) strip light bulb. The first-order decay constant of toluene and formaldehyde found in this study ranged from 0.381 to 1.01 hr Ϫ1 under different total air change rates, from 0.34 to 0.433 hr Ϫ1 under different RH, and from 0.381 to 0.433 hr Ϫ1 for different photocatalytic filters.

Investigation of A Potted Plant (Hedera helix) with Photo-Regulation to Remove Volatile Formaldehyde for Improving Indoor Air Quality

“…Indoor air handling systems with HEPA filters control the ambient environmental conditions, including the temperature, humidity, air flow and air cleaning (Russell et al, 2014). However, filtration does not reduce the levels of all indoor air pollutants, and some types can actually exacerbate the problem (Yu et al, 2006). Chemicals or particles can penetrate indoors through the building envelope, affecting the indoor PM 2.5 levels in real housing units with a controlled indoor-outdoor pressure differences (Choi and Kang, 2017).…”

A Study on Dynamic Volatile Organic Compound Emission Characterization of Water-Based Paints

“…There has been growing public concern about air quality in urban areas. 8 The Taiwan Environmental Protection Agency announced the Indoor Air Quality Act (IAQA) in 2008 and implemented some initiatives to control the domestic VOC emission inventory.…”

Applying the Membrane-Less Electrolyzed Water Spraying for Inactivating Bioaerosols

“…Therefore, an increasing number of air-cleaning technologies are being adopted to remove indoor bioaerosols. Currently, bioaerosol removal approaches include electret filtration (Yang and Lee, 2005;Yang et al, 2007), electrostatic precipitation (Li and Wen, 2003), ozone (Li and wang, 2003), ultraviolet germicidal irradiation (Lin and Li, 2002;Lee, 2011;Park et al, 2012), photocatalytic oxidation (Lin and Li, 2003), negative ions (Yu et al, 2006), Plasma technology (Yang et al, 2011).…”