Quantum efficiencies in a multi-annular photocatalytic reactor

2007 ◽  
Vol 55 (12) ◽  
pp. 161-166 ◽  
Author(s):  
G.E. Imoberdorf ◽  
H.A. Irazoqui ◽  
A.E. Cassano ◽  
O.M. Alfano
Keyword(s):  
Mathematical Model ◽  
Quantum Efficiency ◽  
Absorption Efficiency ◽  
Radiative Energy ◽  
Radiation Absorption ◽  
Reactor Radiation ◽  
Photocatalytic Reactor ◽  
Operating Variables ◽  
Radiation Incidence

Radiative energy efficiencies of a multi-annular photocatalytic reactor were evaluated and analysed. The total quantum efficiency, defined as the ratio of the number of molecules of the pollutant reacted to the number of photons emitted by the lamp, is expressed as the product of three factors: (i) the reactor radiation incidence efficiency, (ii) the catalyst radiation absorption efficiency, and (iii) the overall reaction quantum efficiency. By means of a detailed mathematical model, the numerical values of each one were 83, 92, and 0–2.5%, respectively. The dependence of the overall reaction quantum efficiency upon operating variables was also studied.

scholarly journals Comprehensive Kinetics of the Photocatalytic Degradation of Emerging Pollutants in a LED-Assisted Photoreactor. S-Metolachlor as Case Study

Catalysts ◽  
2020 ◽  
Vol 11 (1) ◽  
pp. 48
Author(s):  
Laura Rancaño ◽  
Maria J. Rivero ◽  
Miguel Ángel Mueses ◽  
Inmaculada Ortiz
Keyword(s):  
Scale Up ◽  
Emerging Pollutants ◽  
Photon Absorption ◽  
Radiation Absorption ◽  
Reactor Performance ◽  
Photocatalytic Reactor ◽  
Operating Variables ◽  
Degradation Reactions ◽  
Volumetric Rate ◽  
Kinetics Of

Although the potential and beneficial characteristics of photocatalysis in the degradation of a good number of emerging pollutants have been widely studied and demonstrated, process design and scale-up are restrained by the lack of comprehensive models that correctly describe the performance of photocatalytic reactors. Together with the kinetics of degradation reactions, the distribution of the radiation field in heterogeneous photocatalytic systems is essential to the optimum design of the technology. Both the Local Volumetric Rate of Photon Absorption (LVRPA) and the Overall Volumetric Rate of Photon Absorption (OVRPA) help to understand this purpose. This work develops a Six-Flux radiation absorption–scattering model coupled to the Henyey–Greenstein scattering phase function to evaluate the LVRPA profile in a LED-assisted photocatalytic reactor. Moreover, the OVRPA has been calculated and integrated into the kinetic equation, accounting for the influence of the radiation distribution on the reaction rate. The model has been validated with experimental data for the degradation of S-Metolachlor (MTLC), and the set of operating variables that maximize the reactor performance, 0.5 g/L of TiO2 P25 and pH 3, has been determined.

scholarly journals Shubnikov–de Haas Oscillations in Semiconductors at the Microwave-Radiation Absorption

2019 ◽  
Vol 2019 ◽  
pp. 1-5
Author(s):  
G. Gulyamov ◽  
U. I. Erkaboev ◽  
A. G. Gulyamov
Keyword(s):  
Experimental Data ◽  
Mathematical Model ◽  
Electromagnetic Field ◽  
Microwave Radiation ◽  
Three Dimensional ◽  
Radiation Absorption ◽  
Narrow Gap ◽  
Proposed Model ◽  
Different Temperatures ◽  
Shubnikov De Haas Oscillations

Mathematical models for the Shubnikov-de Haas oscillations in semiconductors are obtained at the microwave-radiation absorption and its temperature dependence. Three-dimensional image of microwave magnetoabsorption oscillations in narrow-gap semiconductors is established. Using a mathematical model, the oscillations of the microwave magnetoabsorption are considered for different values of the electromagnetic field. The results of calculations are compared with experimental data. The proposed model explains the experimental results in HgSe at different temperatures.

Effect of laser radiation absorption efficiency on the heating temperature of inclusions in transparent media

2012 ◽  
Vol 48 (6) ◽  
pp. 705-708 ◽  
Author(s):  
V. G. Kriger ◽  
A. V. Kalenskii ◽  
A. A. Zvekov ◽  
I. Yu. Zykov ◽  
B. P. Aduev
Keyword(s):  
Laser Radiation ◽  
Heating Temperature ◽  
Absorption Efficiency ◽  
Radiation Absorption ◽  
Transparent Media

Quantum efficiency of non-radiative energy transfer from Eu3+ → Pr3+ in calibo glass

1978 ◽  
Vol 28 (9) ◽  
pp. 807-810 ◽  
Author(s):  
H.B. Tripathi ◽  
A.K. Agarwal ◽  
H.C. Kandpal ◽  
R. Belwal
Keyword(s):  
Energy Transfer ◽  
Quantum Efficiency ◽  
Radiative Energy ◽  
Radiative Energy Transfer

scholarly journals On the Optical Response of Tellurium Activated Zinc Selenide ZnSe:Te Single Crystal

Crystals ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 961
Author(s):  
Dionysios Linardatos ◽  
Anastasios Konstantinidis ◽  
Ioannis Valais ◽  
Konstantinos Ninos ◽  
Nektarios Kalyvas ◽  
...  
Keyword(s):  
Single Crystal ◽  
Energy Absorption ◽  
Quantum Efficiency ◽  
Zinc Selenide ◽  
Light Output ◽  
Absorption Efficiency ◽  
Detective Quantum Efficiency ◽  
X Ray ◽  
Luminescence Efficiency ◽  
Energy Absorption Efficiency

In this study, the light output of a zinc selenide activated with tellurium (ZnSe: Te) single crystal was measured for X-ray radiography applications. A cubic crystal (10 × 10 × 10 mm) was irradiated using X-rays with tube voltages from 50 to 130 kV. The resulting energy absorption efficiency, detective quantum efficiency, and absolute luminescence efficiency were compared to published data for equally sized GSO: Ce (gadolinium orthosilicate) and BGO (bismuth germanium oxide) crystals. The emitted light was examined to estimate the spectral compatibility with widely used optical sensors. Energy absorption efficiency and detective quantum efficiency of ZnSe: Te and BGO were found to be similar, within the X-ray energies in question. Light output of all three crystals showed a tendency to increase with increasing X-ray tube voltage, but ZnSe: Te stood at least 2 EU higher than the others. ZnSe: Te can be coupled effectively with certain complementary metal–oxide–semiconductors (CMOS), photocathodes, and charge-coupled-devices (CCD), as the effective luminescence efficiency results assert. These properties render the material suitable for various imaging applications, dual-energy arrays included.

A Mathematical Model for the Performance of a Horizontal Convective Solar Still

2005 ◽  
Author(s):  
M. Feng ◽  
Y.-X. Tao
Keyword(s):  
Mathematical Model ◽  
Solar Radiation ◽  
Flow Direction ◽  
Vertical Direction ◽  
Operating Conditions ◽  
Radiation Absorption ◽  
Solar Still ◽  
Materials Used ◽  
The One ◽  
Physical Phenomena

A mathematical model is developed to predict the rate of distilled water production for a solar still with convective, double-deck configuration. The model is based on the one-dimensionally distributed formulation in the flow direction and two media treatment in the vertical direction. Different operating conditions are investigated to include different airflow rates, variable rates of solar radiation and ambient temperature. The effects of materials used in the still canopy and physical phenomena such as solar radiation absorption of liquid film on the performance are also investigated. The comparisons between the model results and fully two-dimensional CFD model results are presented.

Simulation of a multi-annular photocatalytic reactor for degradation of perchloroethylene in air: Parametric analysis of radiative energy efficiencies

2007 ◽  
Vol 62 (4) ◽  
pp. 1138-1154 ◽  
Author(s):  
Gustavo E. Imoberdorf ◽  
Alberto E. Cassano ◽  
Horacio A. Irazoqui ◽  
Orlando M. Alfano
Keyword(s):  
Parametric Analysis ◽  
Radiative Energy ◽  
Photocatalytic Reactor

scholarly journals Investigating of Radiation Absorption and Use Efficiency in Intercropping of Wheat and Canola

2015 ◽  
Vol 9 (6) ◽  
pp. 61-71 ◽  
Author(s):  
Kolsoum Karimian ◽  
Reza Ghorbani ◽  
Ali-Reza Koochaki ◽  
Ghorban-Ali Asadi
Keyword(s):  
Seed Yield ◽  
Absorption Efficiency ◽  
Radiation Absorption ◽  
Use Efficiency

In order to investigate RAE and RUE in alternative intercropping of wheat-canola, an experiment was carried out in a field located in Shirvan in 2013-2014. The experiment plan was arranged in factorial-RCBD with 3 replications. Treatments included 3 different ratio of density (for wheat T1=250, T2=300 and T3=350; for canola C1=80, C2=100 and C3=120 plant/m2) and 7 planting ratios (D0=canola monoculture, D1=25:75(wheat:canola), D2=50:50, D3=75:25 and D4=wheat monoculture). The results showed that density of planting ratio and their interactions had a significant effects on absorption efficiency, seed yield and RUE . In intercropping treatments, seed yield of canola was more than monoculture, but it was less than of wheat monoculture. The more seed yield of wheat was gained from T2 in monoculture (1165.62 g/m2). RUE was affected by the different intercropping patterns. The value of RUE in intercropping was more than one in monoculture of both species. The best results of planting combination were gained T2C2D2 with 1.91 g/m2.Mj RUE for wheat and T2C2D1 with 1.24 g/m2.Mj RUE for canola.

Detective quantum efficiency for photon-counting hybrid pixel detectors in the tender X-ray domain: application to Medipix3RX

2016 ◽  
Vol 23 (1) ◽  
pp. 206-213 ◽  
Author(s):  
Jean Rinkel ◽  
Debora Magalhães ◽  
Franz Wagner ◽  
Florian Meneau ◽  
Flavio Cesar Vicentin
Keyword(s):  
Energy Range ◽  
Quantum Efficiency ◽  
Imaging Techniques ◽  
Photon Counting ◽  
Absorption Efficiency ◽  
Detective Quantum Efficiency ◽  
Electronic Noise ◽  
X Rays ◽  
X Ray ◽  
Pixel Detectors

Synchrotron-radiation-based X-ray imaging techniques using tender X-rays are facing a growing demand, in particular to probe theKabsorption edges of low-Zelements. Here, a mathematical model has been developed for estimating the detective quantum efficiency (DQE) at zero spatial frequency in the tender X-ray energy range for photon-counting detectors by taking into account the influence of electronic noise. The experiments were carried out with a Medipix3RX ASIC bump-bonded to a 300 µm silicon sensor at the Soft X-ray Spectroscopy beamline (D04A-SXS) of the Brazilian Synchrotron Light Laboratory (LNLS, Campinas, Brazil). The results show that Medipix3RX can be used to develop new imaging modalities in the tender X-ray range for energies down to 2 keV. The efficiency and optimal DQE depend on the energy and flux of the photons. The optimal DQE values were found in the 7.9–8.6 keV photon energy range. The DQE deterioration for higher energies due to the lower absorption efficiency of the sensor and for lower energies due to the electronic noise has been quantified. The DQE for 3 keV photons and 1 × 104 photons pixel−1s−1is similar to that obtained with 19 keV photons. Based on our model, the use of Medipix3RX could be extended down to 2 keV which is crucial for coming applications in imaging techniques at modern synchrotron sources.

Modeling the Solar Photocatalytic Degradation of Dyes

2006 ◽  
Vol 129 (1) ◽  
pp. 87-93 ◽  
Author(s):  
H. I. Villafán-Vidales ◽  
S. A. Cuevas ◽  
C. A. Arancibia-Bulnes
Keyword(s):  
Absorption Coefficient ◽  
Photocatalytic Degradation ◽  
Linear Trend ◽  
Wavelength Region ◽  
Radiation Absorption ◽  
Polluted Water ◽  
Photocatalytic Reactor ◽  
Degradation Of Dyes ◽  
Degradation Rates ◽  
Photocatalytic Reactors

Background. The calculation of radiation absorption by the catalyst in solar photocatalytic reactors has been addressed by some authors, because it is a necessary step for the modeling of the detoxification of polluted water in these systems. Generally transparent pollutants have been considered, which somewhat simplifies the calculations. However, there has been an increasing interest in the study of solar photocatalytic degradation of dyes. These substances are not transparent to the radiation that the catalyst is able to absorb, and therefore their optical properties must be taken into account in the radiative modeling. Method of Approach. Absorption of radiation by the catalyst suspended in colored water is modeled by using the P1 approximation of radiative transfer theory. The absorption coefficient of the dye is taken into account in these calculations. A kinetic model is used to model degradation rates, based on the results of the radiative calculations. This has to be done through an Euler type method, because the reduction of dye concentration constantly modifies the optical conditions on the reactor, requiring a recalculation of radiation absorption at each step. Also, photocatalytic degradation experiments were carried out in a CPC solar photocatalytic reactor with tubular reaction space. Degradation of the Acid Orange 24 Azo dye was studied. The experimental degradation rates are compared with theoretical predictions. Results. An important influence of dye concentration is observed in the distribution of absorbed radiation, and also this parameter has a notorious effect on the predicted degradation rates. As a function of catalyst concentration, the degradation rate first increases rapidly and then at a smaller pace with an apparent linear trend. The experimental results can be reproduced well by the model. Conclusions. The proposed methodology allows modeling the solar photocatalytic degradation of dyes. The method should be applicable as long as the dye absorption coefficient is not too high in the wavelength region where the catalyst absorbs.

Sign in / Sign up

Export Citation Format

Share Document