scholarly journals Symmetrization and Amplification of Germicidal Radiation Flux Produced by a Mercury Amalgam UV Lamp in Cylindrical Cavity with Diffusely Reflective Walls

Symmetry ◽  
2022 ◽  
Vol 14 (1) ◽  
pp. 125
Author(s):  
Mikhail A. Kotov ◽  
Andrey N. Shemyakin ◽  
Nikolay G. Solovyov ◽  
Mikhail Y. Yakimov
Keyword(s):  
Uv Radiation ◽  
Radiation Flux ◽  
Visible Range ◽  
Source Surface ◽  
Mercury Lamp ◽  
Surface Absorption ◽  
Cylindrically Symmetric ◽  
Symmetric Cavity ◽  
Diffuse Reflectivity ◽  
Cylindrical Cavities

The study focused on increasing the efficiency of germicidal UV radiation by using highly diffuse reflective materials such as PTFE in irradiated cavities of UV air purifiers. In a conventional cylindrically symmetric cavity with a linear amalgam mercury lamp as UV-radiation source on the axis UV-radiation, flux directed from the lamp to the walls dropped from the axis to the periphery. To increase the UV irradiation, the walls are often made mirror-reflective, but the radiation flux distribution remained radially symmetric with a maximum on the source emitting surface in this case as well. When most of the emitted light is returned to the source after one reflection, the conditions of its operation are disturbed. If the walls are made of highly diffuse reflective materials, the radiation flux density inside the cavity increases on average, and its distribution becomes uniform and highly symmetric. Thus, the effect of amplification of the radiation flux due to the highly diffuse reflectivity of the walls increases with radius and reaches a maximum at the wall. Experiments were performed to demonstrate increasing amplification of germicidal UV radiation flux with a diffuse reflection coefficient in cylindrical cavities with walls of PTFE and ePTFE. The irradiation of the cavity wall was observed to increase up to 20 times at the resonant mercury line of 253.7 nm and up to 40 times at some non-resonant lines of the visible range due to highly diffuse reflectivity of the cavity walls. The flux amplification effect was limited by the diffuse reflectivity value of the walls and absorption coefficient of the radiation emitting surface. A formula for calculating the radiation flux amplification factor in a diffusely reflecting cylindrically symmetric cavity was derived for the case of Lambertian source and reflector, including wall reflectivity and source surface absorption coefficients. The effects of heating and cooling of the mercury lamp amalgam directly affected the amplification, and symmetrization of germicidal irradiation was observed and is discussed in the paper. Numerical calculations were performed by the ray tracing method. The calculated model was verified by comparing the numerical results with those of both the approximate theoretical consideration and experiments. The promising use of diffusely reflecting cylindrical cavities for UV air purifiers is discussed. Designs of air inlet and outlet ports that allow effective locking of germicidal radiation inside the UV air purifiers were considered. The results of this work may be of interest for further developments in the UV disinfection technique.

scholarly journals Removal Of Phenol From Wastewater By Using Low-Cost Catalyst From Metal Production

2014 ◽  
Vol 22 (341) ◽  
pp. 55-59
Author(s):  
Blanka Galbičková ◽  
Maroš Soldán ◽  
Michal Belčík ◽  
Karol Balog
Keyword(s):  
Uv Radiation ◽  
Red Mud ◽  
Advanced Oxidation Processes ◽  
Low Cost ◽  
Advanced Oxidation ◽  
Emerging Technology ◽  
Mercury Lamp ◽  
Metal Production ◽  
Oxidation Processes ◽  
Uv Photodegradation

Abstract Utilization of AOPs (Advanced oxidation processes) as an emerging technology for removing of pollutants from wastewater is developed. In this paper, UV photodegradation was used for removing of phenol from wastewater. As a source of UV radiation medium pressure mercury lamp with output 400W was used. The influence of low-cost catalysts on this process was also monitored. Wastes from metal production, red mud and black nickel mud, were used as catalysts.

Inactivation of E. coli and helminth eggs in aerobic and anaerobic effluents using UV radiation

2003 ◽  
Vol 47 (9) ◽  
pp. 185-192 ◽  
Author(s):  
C.A. de Lemos Chernicharo ◽  
J.C. de Castro Silva ◽  
A.M. Zerbini ◽  
V.M. Godinho
Keyword(s):  
Uv Radiation ◽  
Ascaris Lumbricoides ◽  
Uasb Reactor ◽  
Mercury Lamp ◽  
Trickling Filter ◽  
Excellent Performance ◽  
E Coli ◽  
Helminth Eggs ◽  
Aerobic And Anaerobic ◽  
Very High

This paper evaluates the performance of a simplified bench-scale UV-photoreactor used to inactivate Escherichia coli and eggs of Ascaris lumbricoides. The photoreactor consisted of a tubular unit constructed with PVC tube, 100 mm diameter and 45 cm total height, with a low-pressure mercury lamp adapted in the centre of the tube. The reactor was tested to disinfect the effluents from a trickling filter and from an UASB reactor, both fed with domestic sewage. The results showed an excellent performance of the photoreactor, with very high E. coli inactivation efficiencies being observed for the aerobic effluent (in the range of 4 to 5 log-units, for doses varying from 50.7 to 13.6 mW.s.cm−2) and also for the effluent from the UASB reactor (usually above 4 log-units, for doses of 20.3 and 13.6 mW.s.cm−2). In relation to the inactivation of helminth eggs, it was observed that UV radiation significantly affected the development of eggs of Ascaris lumbricoides, with the better results being obtained for radiation times of 40 and 60 seconds (doses of 13.6 and 20.3 mW.s.cm−2, respectively), when approximately 65% of the eggs remained in the stage of single cell and only 9 to 10% were able to fully develop to the stage of motile larva.

Comparative study of UV radiation action of XeBr-excilamp and conventional low-pressure mercury lamp on bacteria

2007 ◽  
Author(s):  
Sergey M. Avdeev ◽  
Edward A. Sosnin ◽  
Ksenia Y. Velichevskaya ◽  
Larisa V. Lavrent'eva
Keyword(s):  
Comparative Study ◽  
Uv Radiation ◽  
Low Pressure ◽  
Mercury Lamp ◽  
Radiation Action

Ozone and life on the Archaean Earth

2007 ◽  
Vol 365 (1856) ◽  
pp. 1889-1901 ◽  
Author(s):  
Charles S Cockell ◽  
John A Raven
Keyword(s):  
Uv Radiation ◽  
Fossil Record ◽  
Radiation Flux ◽  
Radiation Environment ◽  
Trace Gas ◽  
Early Earth ◽  
Case Scenario ◽  
Worst Case ◽  
Colonization Of Land ◽  
Early Land

The trace gas ozone, produced in the present-day stratosphere, acts as a screen for UV radiation between 195 and approximately 290 nm, depending on its column abundance. On the anoxic Archaean Earth, such an ozone screen would not have existed. Although the presence of other screens, such as an organic haze, might have ameliorated the UV radiation flux, even assuming the worst-case scenario (no UV screen), it can be shown that early land masses and the photic zone of the oceans could have been colonized, suggesting that: (i) high UV radiation would not have prevented the colonization of land and (ii) it is unlikely that the fossil record can be used to constrain estimates of the UV radiation environment of the early Earth (although geochemical approaches and the study of extrasolar planetary atmospheres are likely to provide empirical constraints on the early photobiological environment).

scholarly journals Dose dependence of visible range diffuse reflectivity for Si+and C+ion implanted polymers

2008 ◽  
Vol 113 ◽  
pp. 012038 ◽  
Author(s):  
S Balabanov ◽  
T Tsvetkova ◽  
E Borisova ◽  
L Avramov ◽  
L Bischoff
Keyword(s):  
Dose Dependence ◽  
Visible Range ◽  
Diffuse Reflectivity ◽  
Ion Implanted

scholarly journals Activation Treatments and SiO2/Pd Modification of Sol–Gel TiO2 Photocatalysts for Enhanced Photoactivity under UV Radiation

Catalysts ◽  
2020 ◽  
Vol 10 (10) ◽  
pp. 1184
Author(s):  
Julien Mahy ◽  
Valériane Sotrez ◽  
Ludivine Tasseroul ◽  
Sophie Hermans ◽  
Stéphanie Lambert
Keyword(s):  
Photocatalytic Activity ◽  
Band Gap ◽  
Uv Radiation ◽  
Diffuse Reflectance Spectroscopy ◽  
Sol Gel ◽  
Pure Tio2 ◽  
Visible Range ◽  
Crystallographic Structure ◽  
Tio2 Sample ◽  
Tio2 Photocatalysts

The objective of this work is to improve the efficiency of TiO2 photocatalysts by activation treatments and by modification with palladium nanoparticles and doping with SiO2. The influence of the additive loading was explored, and two activation treatments were performed: UV exposition and H2 reduction. TiO2/SiO2/Pd photocatalysts were synthesized by an original cogelation method: a modified silicon alkoxide, i.e., [3-(2-aminoethyl)aminopropyl]trimethoxysilane (EDAS), was used to complex the palladium ions, thanks to the ethylenediamine group, while the alkoxide groups reacted with TiO2 precursors. Pure TiO2 was also synthesized by the sol–gel process for comparison. X-ray diffraction evidenced that the crystallographic structure of TiO2 was anatase and that Pd was present, either in its oxidized form after calcination, or in its reduced form after reduction. The specific surface area of the samples varied from 5 to 145 m2 g-1. Transmission electron microscopy allowed us to observe the homogeneous dispersion and nanometric size of Pd particles in the reduced samples. The width of the band gap for pure TiO2 sample, measured by UV/Visible diffuse reflectance spectroscopy at approximately 3.2 eV, corresponded to that of anatase. The band gap for the TiO2/SiO2/Pd composite samples could not be calculated, due to their high absorption in visible range. The photocatalytic activity of the various catalysts was evaluated by the degradation of a methylene blue solution under UV radiation. The results showed that the photocatalytic activity of the catalysts was inversely proportional to the content of silica present in the matrix. A small amount of silica improved the photocatalytic activity, as compared to the pure TiO2 sample. By contrast, a high amount of silica delayed the crystallization of TiO2 in its anatase form. The activation treatment under UV had little influence on photocatalytic efficiency. The introduction of Pd species increased the photocatalytic activity of the samples because it allowed for a decrease in the rate of electron–hole recombinations in TiO2. The reduction treatment improved the activity of photocatalysts, whatever the palladium content, thanks to the reduction of Ti4+ into Ti3+, and the formation of defects in the crystallographic structure of anatase.

scholarly journals The photoluminescent layers based on ZnO nanoparticles as radiation converters in photovoltaic applications

2018 ◽  
pp. 16-26 ◽  
Author(s):  
Natalia Szczecińska ◽  
Katarzyna Znajdek ◽  
Aleksandra Sosna-Głębska ◽  
Paul Lewicki ◽  
Przemysław Czarnecki ◽  
...  
Keyword(s):  
Solar Cell ◽  
Uv Radiation ◽  
High Efficiency ◽  
Solar Spectrum ◽  
Optical Transmittance ◽  
Photovoltaic Cell ◽  
Visible Range ◽  
Zno Nps ◽  
Luminescence Efficiency ◽  
Down Conversion

The mismatch between solar cell response and solar spectrum is one of the biggest challenges to achieve high efficiency in photovoltaic cells. There are a few different approaches to minimise this concern. One of them is the radiation conversion which may be due to three different processes, namely up-conversion, down- conversion and down-shifting. In this paper the down-conversion process of zinc oxide nanoparticles (ZnO NPs) and layers with ZnO NPs in polymer (poly (methyl methacrylate)) (PMMA) matrix will be analysed. ZnO NPs are prone to act as down-converting or down-shifting agents, which absorb the UV radiation, which is not absorbed by the solar cell, and then re-emit light in the visible range, which is suited to the photovoltaic cell sensitivity. Herein, the photoluminescence and optical transmittance of ZnO NPs and layers based on ZnO NPs will be presented. These parameters have a large influence on the potential application of these layers in photovoltaic structures for increased efficiency. The conversion layers have to fulfil the following conditions: have good optical transmittance in the visible range and high luminescence efficiency in converting UV radiation into visible. The paper focuses on finding the balance between these parameters.

Prognostic Ozone for ICON: Enabling UV Forecasts

2021 ◽  
Author(s):  
Simon Weber ◽  
Roland Ruhnke ◽  
Peter Braesicke ◽  
Christian Scharun
Keyword(s):  
Uv Radiation ◽  
Radiation Flux ◽  
Stratospheric Ozone ◽  
Regional Scale ◽  
Radiative Transfer Model ◽  
Transfer Model ◽  
Human Beings ◽  
Geophysical Research ◽  
Uv Index ◽  
Index Maps

<p>Stratospheric Ozone (O<sub>3</sub>) absorbs biologically harmful solar ultraviolet radiation (most of the UV‑B radiation) and keeps it from reaching the surface. Such UV radiation is destructive of genetic cellular material in plants and animals, as well as human beings. Without the ozone layer, life on the surface of the Earth would not be possible as we know it.</p><p>As part of its work the German Weather Service (DWD) provides UV index maps to warn the population in Germany of excessive UV exposure <sup>[[1]]</sup>. For this purpose, global ICON data, external ozone data and an external UV model is used.</p><p>This study aims to create a self-consistent framework to generate UV index maps entirely from the non-hydrostatic global modelling system ICON <sup>[[2]]</sup>. For this purpose, a linearized ozone scheme (LINOZ) <sup>[[3]] </sup>will be optimized and the forecast functionality of ICON-ART <sup>[[4]][[5]]</sup> (ICOsahedral Non-hydrostatic – Aerosols and Reactive Trace gases) will be extended. For the derivation of UV radiation fluxes and indices a radiative transfer model for solar radiation (Cloud-J) <sup>[[6]]</sup> shall be implemented and extended. Since the entire framework is to be used at the DWD during ongoing operations, a functionality with very low computational effort is required.  </p><p>Here we present the first results of the UV radiation flux through the atmosphere and its diurnal variation. Furthermore, the influence of clouds on the UV radiation flux is considered.</p><div><br><div> <p><sup>[[1]]</sup> https://kunden.dwd.de/uvi/index.jsp</p> </div> <div> <p><sup>[[2]]</sup> Zängl, G., et al. (2014), The ICON (ICOsahedral Non-hydrostatic) modelling framework of DWD MPI-M: Description of the non-hydrostatic dynamical core. Q.J.R. Meteorol. Soc., doi:10.1002/qj.2378</p> </div> <div> <p><sup>[[3]]</sup> McLinden, C. A., et al. (2000), Stratospheric ozone in 3-D models: A simple chemistry and the cross-tropopause flux, Journal of Geophysical Research: Atmospheres, doi:10.1029/2000JD900124</p> </div> <div> <p><sup>[[4]]</sup> Rieger, D., et al. (2015), ICON-ART - A new online-coupled model system from the global to regional scale, Geosci. Model Dev., doi:10.5194/gmd-8-1659-2015</p> </div> <div> <p><sup>[[5]]</sup> Schröter, et al. (2018), ICON-ART 2.1: a flexible tracer framework and its application for composition studies in numerical weather forecasting and climate simulations. Geosci. Model Dev., doi:10.5194/gmd-11-4043-2018</p> </div> <div> <p><sup>[[6]]</sup> Prather, M.J. (2015), Photolysis rates in correlated overlapping cloud fields: Cloud-J 7.3c. Geosci. Model Dev., doi:10.5194/gmd-8-2587-2015</p> </div> </div>

Evolution of Large-Scale Coronal Structures

1994 ◽  
Vol 144 ◽  
pp. 29-33
Author(s):  
P. Ambrož
Keyword(s):  
Magnetic Field ◽  
Field Line ◽  
Large Scale ◽  
Coronal Magnetic Field ◽  
Source Surface ◽  
Solar Cycles ◽  
Characteristic Relationship ◽  
The Magnetic Field ◽  
Coronal Structures

AbstractThe large-scale coronal structures observed during the sporadically visible solar eclipses were compared with the numerically extrapolated field-line structures of coronal magnetic field. A characteristic relationship between the observed structures of coronal plasma and the magnetic field line configurations was determined. The long-term evolution of large scale coronal structures inferred from photospheric magnetic observations in the course of 11- and 22-year solar cycles is described.Some known parameters, such as the source surface radius, or coronal rotation rate are discussed and actually interpreted. A relation between the large-scale photospheric magnetic field evolution and the coronal structure rearrangement is demonstrated.

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