Resolving UV photometer outputs with modeled intensity profiles

Severin, Blaine F.; Roessler, Peter F.

doi:10.1016/s0043-1354(97)00363-1

Cited by 14 publications

(10 citation statements)

References 2 publications

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“…The modeling of photoreactors is difficult due to complex reaction kinetics, light intensity gradients created by dispersion, absorption, reflection and shadowing, and hydraulically complex mixing profile [78]. LVREA is a non-uniform factor even in mixed reactor due to the absorption, scattering and geometrical effects and it is essential that light intensity be known precisely through the reactor [83].…”

Section: Reactor and Light Modelingmentioning

confidence: 99%

Photodegradation of the Volatile Organic Compounds in the Gas Phase: A Review

Ray

2000

Dev. Chem. Eng. Mineral Process.

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SINGAPORE 11 7576 ~~ A review of photodegradation processes suitable for the treatment of Volatile OrganicCompounds (VOCs) present in the efluents from air-stripping and soil-vapor extraction is presented. This paper outlines and summarizes the essential factors such as kinetics and mechanism, intermediates of degradation processes, and reactor modeling which lead to the successful application of this useful technology. In addition, the effects of operating parameters such as humidity, temperature, additives and types of VOCs are discussed. The review also identijies the areas where further work is needed.

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Section: Reactor and Light Modelingmentioning

confidence: 99%

Photodegradation of the Volatile Organic Compounds in the Gas Phase: A Review

Ray

2000

Dev. Chem. Eng. Mineral Process.

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“…The detector (model number: ILX-511B) measurement range was 200–850 nm with an optical bench entrance aperture of 50-μm width. Since the radiation profile of a UV-LED is directional, the detector was equipped with a cosine corrector (with Spectralon diffusing material) to ensure irradiance measurements . The cosine corrector reads the normal vector of the incident photon to its surface which is equal to the irradiance at that point.…”

Section: Materials and Methodsmentioning

confidence: 99%

Protocol for Determining Ultraviolet Light Emitting Diode (UV-LED) Fluence for Microbial Inactivation Studies

Kheyrandish

Mohseni

Taghipour

2018

Environ. Sci. Technol.

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Determining fluence is essential to derive the inactivation kinetics of microorganisms and to design ultraviolet (UV) reactors for water disinfection. UV light emitting diodes (UV-LEDs) are emerging UV sources with various advantages compared to conventional UV lamps. Unlike conventional mercury lamps, no standard method is available to determine the average fluence of the UV-LEDs, and conventional methods used to determine the fluence for UV mercury lamps are not applicable to UV-LEDs due to the relatively low power output, polychromatic wavelength, and specific radiation profile of UV-LEDs. In this study, a method was developed to determine the average fluence inside a water suspension in a UV-LED experimental setup. In this method, the average fluence was estimated by measuring the irradiance at a few points for a collimated and uniform radiation on a Petri dish surface. New correction parameters were defined and proposed, and several of the existing parameters for determining the fluence of the UV mercury lamp apparatus were revised to measure and quantify the collimation and uniformity of the radiation. To study the effect of polychromatic output and radiation profile of the UV-LEDs, two UV-LEDs with peak wavelengths of 262 and 275 nm and different radiation profiles were selected as the representatives of typical UV-LEDs applied to microbial inactivation. The proper setup configuration for microorganism inactivation studies was also determined based on the defined correction factors.

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“…Importantly, PCI-borosilicate only meets the angular response design specification (i.e., magnitude of cosine error ≤10%) at near-normal angles of incidence: 0º (due to normalization) and 15º empirically, and up to ~29º analytically. While angle-specific correction factors have been determined and applied in tightly controlled systems 24 , this approach is not feasible when the distribution of angles of incidence is not precisely known. For N95s in a UV-C chamber, both the 3D N95 facepiece morphology and uncollimated radiation confound application of an angle-specific correction factor to adjust inaccurate on-N95 UV-C dose measurements.…”

Section: Analytical and Empirical Characterization Demonstrate Non-id...mentioning

confidence: 99%

Optical Attenuators Extend Dynamic Range but Alter Angular Response of Planar Ultraviolet‐C Dosimeters

Geldert

Grist

Herr

2021

Photochem & Photobiology

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A challenge for sensors used in ultraviolet-C (UV-C) decontamination protocols of N95 respirators is validation that the entire N95 surface receives the minimum acceptable dose. Photochromic indicators (PCIs) can accurately measure UV-C dose on nonplanar surfaces, but often saturate below doses required to decontaminate porous, multilayered textiles such as N95s. Here, we investigate the use of optical attenuators to extend PCI dynamic range while maintaining a nearideal angular response -critical for accurate measurements when UV-C is uncollimated. Through an analytical model, we show that tuning attenuator refractive index, attenuation coefficient, and thickness can extend dynamic range, but compromises ideal angular response unless the attenuator is an ideal diffuser. To demonstrate this tradeoff empirically, we pair PCIs with model specular (floated borosilicate) and diffuse (polytetrafluoroethylene) attenuators, characterize the angular response, and evaluate on-N95 UV-C dose measurement accuracy of each PCI-attenuator stack in a UV-C decontamination system. While both borosilicate and polytetrafluoroethylene increase PCI dynamic range >4×, both attenuators introduce angle-dependent transmittance, which causes location-dependent underestimation of UV-C dose. The PCI-borosilicate and PCIpolytetrafluoroethylene stacks underreport true on-N95 dose by 1) 14.7% and 3.6%, respectively, on a surface near-normal to the array of source lamps, and 2) 40.8% and 19.8%, respectively, on a steeply sloped location. Overall, we demonstrate that while planar optical attenuators can increase PCI dynamic range, verification of near-ideal angular response is critical for accurate UV-C dose measurement.

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Resolving UV photometer outputs with modeled intensity profiles

Cited by 14 publications

References 2 publications

Photodegradation of the Volatile Organic Compounds in the Gas Phase: A Review

Photodegradation of the Volatile Organic Compounds in the Gas Phase: A Review

Protocol for Determining Ultraviolet Light Emitting Diode (UV-LED) Fluence for Microbial Inactivation Studies

Optical Attenuators Extend Dynamic Range but Alter Angular Response of Planar Ultraviolet‐C Dosimeters

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