TiO2奈米光触媒滤网应用于空调系统分解甲醛气体之研究.DOC

Decomposition of Formaldehyde by TiO2 Nanocatalyst Filters in a Heating Ventilation Air Conditioning System ABSTRACT This paper investigates the effectiveness of TiO2 photocatalytic oxidation of formaldehyde under different heating ventilation air conditioning (HVAC)-related air conditions. Formaldehyde, at a specific concentration, was injected into an enclosed HVAC test chamber, and circulated under UV irradiation though TiO2 nanofilm-coated stainless steel air filter. After two hours of HVAC operation under preset temperature, relative humidity (RH), and air velocity conditions, the formaldehyde photocatalyst decomposition effectiveness was 65–87%. At constant RH and air velocity, photocatalysis increased with an increase in air temperature. At 40–60% RH, and constant temperature and air velocity, the photocatalytic degradation rates were 78–89%. Under constant temperature and RH conditions, and air velocities of 0.4–1.3 m/s (1.3–4.3 ft/s), the formaldehyde decomposition efficiency was 70–86%. Therefore, in a sealed system, when one or all of air temperature, RH, and air velocity are increased, the formaldehyde photodegradation rate will be increased. Keywords: Formaldehyde, Photocatalyst, Filter, HVAC, Photocatalytic Oxidation INTRODUCTION Due to deficiencies in natural ventilation or air exchange in the indoor environment of buildings, mechanical ventilation equipment may be installed to maintain quality standards, and health and comfort levels of the indoor air. However, when excessive indoor related materials or chemical-based products are present in the indoor environment, harmful chemical substances may be produced (Chiang, 2006), including volatile organic compounds (VOCs) from solvent-based paint and formaldehyde from wooden or other construction materials. These substances are just two indoor factors that may affect human health. A common pollutant of the indoor environment is Volatile organic compounds (VOCs) and formaldehyde (Zhang, 2007), which