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Air Purifier for Hospital Wards
Published in P. C. Thomas, Vishal John Mathai, Geevarghese Titus, Emerging Technologies for Sustainability, 2020
Bibin Saji, Jolly K. Jerrit, S. K. Bharath, George Sebastian, Mathew J. Joseph
HEPA filters are composed of a mat of randomly arranged fibers. The fibers are typically composed of fiberglass and have diameters between 0.5 and 2.0 micrometers. Key factors affecting its functions are fiber diameter, filter thickness, and face velocity. The air space between HEPA filter fibers is typically much greater than 0.3 μm. The common assumption that a HEPA filter acts like a sieve where particles smaller than the largest opening can pass through is incorrect and impractical. Unlike membrane filters at this pore size, where particles as wide as the largest opening or distance between fibers cannot pass in between them at all, HEPA filters are designed to target much smaller pollutants and particles. Here UV radiations are also used along with the photocatalytic filter. Ultraviolet germicidal irradiation (UVGI) is a disinfection method that uses short-wavelength ultraviolet (UV-C) light to kill or inactivate microorganisms by destroying nucleic acids and disrupting their DNA, leaving them unable to perform vital cellular functions is used in a variety of applications, such as food, air, and water purification-C light is weak at the Earth’s surface as the ozone layer of the atmosphere blocks it. UVGI devices can produce strong enough UV-C light in circulating air or water systems to make them inhospitable environments to microorganisms such as bacteria, viruses, molds and other pathogens. UVGI can be coupled with a filtration system to sanitize air and water.
Borate Phosphor for Phototherapy Application
Published in S. K. Omanwar, R. P. Sonekar, N. S. Bajaj, Borate Phosphors, 2022
Ultraviolet germicidal irradiation (UVGI) is an established means of disinfection and can be used to prevent the spread of certain infectious diseases. For the purpose of germicidal irradiation low-pressure mercury (Hg) discharge lamps are commonly used, the shortwave ultraviolet-C (100–280 nm) radiation, primarily at 254 nm is used for germicidal application. The UVC radiation kills or inactivates microbes by damaging their deoxyribonucleic acid (DNA). The principal mode of inactivation occurs when the absorption of a photon forms pyrimidine dimers between adjacent thymine bases and renders the microbe incapable of replicating [96].
Terminal Systems and Components
Published in Herbert W. Stanford, Adam F. Spach, Analysis and Design of Heating, Ventilating, and Air-Conditioning Systems, 2019
Herbert W. Stanford, Adam F. Spach
Ultraviolet germicidal irradiation (UVGI) generally refers to UV wavelength of 254.7 nm. The wavelength is near optimal for damaging nucleic acid (DNA, RNA). UV irradiation by itself does not clean air. The microorganisms are still there and, in the case of some microorganisms, may still contain the ability to cause noninfectious (e.g., allergenic) disease. While there is potential for UV to destroy allergenic sites on the surface of a bioaerosol, this ability has not been documented or quantified.
Evaluation of in-duct UV-C lamp array on air disinfection: A numerical analysis
Published in Science and Technology for the Built Environment, 2020
Fatih Atci, Yunus Emre Cetin, Mete Avci, Orhan Aydin
The filtration of air is based on trapping and adsorption mechanism (Sutherland 2008). Filters are easy to install and, a variety of filter types are available in the market, depending on the requirement of different air quality criteria for particular applications. However, they must be replaced regularly since an increase of the contamination in the filter media may cause reintroducing of airborne microorganisms into the indoor environment (Ryan et al. 2010). Also, filters induce a large pressure drop that would increase the overall energy consumption of the ventilation system (Fisk et al. 2002; Liu et al. 2017). For these reasons, in addition to physical removal components, other effective approaches such as ultraviolet germicidal irradiation (UVGI) can be considered for inactivation of pathogens in air.
The role of the built environment in updating design requirements in the post-pandemic scenario: a case study of selected diagnostic facilities in Brazil
Published in Architectural Engineering and Design Management, 2022
Ana J. G. Limongi França, Sheila Walbe Ornstein
Among the available technologies for disinfection are ultraviolet germicidal irradiation (UVGI) lamps. The ultraviolet radiation is effective in deactivating not only the SARS-CoV-2 virus but also other respiratory pathogens, such as the Mycobacterium tuberculosis (Mphaphlele et al., 2015). Therefore, an alternative for interior spaces used by many people is to have a UVGI lighting system for permanent disinfection. For this purpose, the radiation wavelength of ∼286 nm could offer efficient virus deactivation (Gerchman, Mamane, Friedman, & Mandelboim, 2020).
Field measurement and modeling of UVC cooling coil irradiation for heating, ventilating, and air conditioning energy use reduction (RP-1738)—Part 2: Energy, indoor air quality, and economic modeling
Published in Science and Technology for the Built Environment, 2018
Joseph Firrantello, William Bahnfleth
Biological growth on cooling coils, biofouling, obstructs airflow and acts as insulation on heat transfer surfaces. It can affect HVAC system performance by increasing energy use of fans, pumps, and refrigeration equipment and, in severe cases, may cause cooling capacity shortfall. Ultraviolet germicidal irradiation (UVGI) is one way of mitigating biofouling and maintaining proper system operation. UVGI inactivates microorganisms, preventing further growth.