scholarly journals Effect of Solvent, Dye-Loading Time, and Dye Choice on the Performance of Dye-Sensitized Solar Cells

2016 ◽  
Vol 2016 ◽  
pp. 1-8 ◽  
Author(s):  
Fahd M. Rajab
Keyword(s):  
Carbon Dioxide ◽  
Supercritical Carbon Dioxide ◽  
Film Thickness ◽  
Energy Conversion ◽  
Supercritical Fluid ◽  
Solvent Mixtures ◽  
Dye Sensitized ◽  
Anatase Titania ◽  
Vis Spectroscopy ◽  
Supercritical Carbon

Anatase titania films with a thickness of up to 20 μm and deposited over a fluorine-doped tin-oxide substrate are impregnated with ruthenium dyes N-719 and N-749 using Dip and supercritical-fluid methods for the purpose of fabricating dye-sensitized solar cell devices. The dyes are dissolved in different solvent mixtures, including supercritical carbon dioxide, as well as combinations of more traditional solvents including mixtures of acetonitrile, and t-butanol. Analytical studies included thin-film analyzing and scanning electron microscopy to measure titania film thickness and porosity, UV-Vis spectroscopy to quantify dye concentration, and current-voltage device characterizations to assess energy conversion efficiency, as well as open-circuit voltage decay measurements and quantum efficiency to examine electron collection efficiency. A significant result is that using the dye N-749 in a solvent that includes supercritical carbon dioxide leads to energy conversion efficiencies that are higher for devices with a thick 20 μm semiconductor film than for the case of devices with thinner films, including the 10 μm film thickness that is traditionally considered an upper threshold. The supercritical-fluid method for the N-719 dye also enabled shorter impregnation duration than more conventional classical Dip Methods.

scholarly journals SPATIAL NONUNIFORM DISTRIBUTION OF 235U ISOTOPE AT SUPERCRITICAL FLUID EXTRACTION WITH CARBON DIOXIDE IN A GRADIENT TEMPERATURE FIELD

2021 ◽  
pp. 98-103
Author(s):  
B.V. Borts ◽  
S.F. Skoromnaya ◽  
Yu. G. Kazarinov ◽  
I.M. Neklyudov ◽  
V.I. Tkachenko
Keyword(s):  
Carbon Dioxide ◽  
Temperature Field ◽  
Supercritical Carbon Dioxide ◽  
Supercritical Fluid ◽  
Separation Factor ◽  
Natural Uranium ◽  
Nonuniform Distribution ◽  
Spatial Redistribution ◽  
Granite Samples ◽  
Supercritical Carbon

The spatial redistribution of the 235U isotope of natural uranium in a gradient temperature field along the height of the reactor in supercritical carbon dioxide has been experimentally investigated. The scheme of the reactor is given and the principle of operation of the reactor is described. The method of preparation of initial samples from granite samples containing natural uranium and the procedure of extraction are described. The conclusion about the spatial redistribution of 235U isotopes in supercritical carbon dioxide is based on the analysis of gamma spectra of extracts. It is shown that the concentration of the 235U isotope in a supercritical fluid is maximal near the lower heated flange of the reactor, and decreases with approaching the upper, cooled flange. It was concluded that the separation factor of the 235U isotope in supercritical carbon dioxide can be about 1.2 ± 0.12.

Generation and Propagation of Thermally Induced Acoustic Waves in Supercritical Fluids: Numerical and Experimental Results

2010 ◽  
Author(s):  
Bakhtier Farouk ◽  
Zhieheng Lei
Keyword(s):  
Carbon Dioxide ◽  
Supercritical Carbon Dioxide ◽  
Supercritical Fluid ◽  
Supercritical Fluids ◽  
Acoustic Waves ◽  
Rapid Heating ◽  
Time Dependent ◽  
Cylindrical Chamber ◽  
Thermally Induced ◽  
Supercritical Carbon

The behavior of thermally induced acoustic waves generated by the rapid heating of a bounding solid wall in a closed cylindrical chamber filled with supercritical carbon dioxide is investigated numerically and experimentally. A time-dependent one-dimensional problem is considered for the numerical simulations where the supercritical fluid is contained between two parallel plates. The NIST Reference Database 12 is used to obtain the property relations for supercritical carbon dioxide. The thermally induced pressure (acoustic) waves undergo repeated reflections at the two confining walls and gradually dissipate. The numerically predicted temperature of the bulk supercritical fluid is found to increase homogeneously (the so called piston effect) within the domain. The details of generation, propagation and dissipation of thermally induced acoustic waves in supercritical fluids are presented under different heating rates. In the experiments, a resistance-capacitance circuit is used to generate a rapid temperature increase in a thin metal foil located at one end of a closed cylindrical chamber. The time-dependent pressure variation in the chamber and the temperature history at the foil are recorded by a fast response measurement system. Both the experimental and numerical studies predict similar pressure wave shapes and profiles due to rapid heating of a wall.

scholarly journals Supercritical Carbon Dioxide Applications for Energy Conversion Systems

2015 ◽  
Vol 82 ◽  
pp. 819-824 ◽  
Author(s):  
Damiano Vitale Di Maio ◽  
Alessandro Boccitto ◽  
Gianfranco Caruso
Keyword(s):  
Carbon Dioxide ◽  
Supercritical Carbon Dioxide ◽  
Energy Conversion ◽  
Energy Conversion Systems ◽  
Supercritical Carbon

Fast Heating Induced Thermoacoustic Waves in Supercritical Fluids: Experimental and Numerical Studies

2013 ◽  
Vol 135 (8) ◽  
Author(s):  
Nusair Hasan ◽  
Bakhtier Farouk
Keyword(s):  
Carbon Dioxide ◽  
Supercritical Carbon Dioxide ◽  
Supercritical Fluid ◽  
Thermal Energy ◽  
Acoustic Waves ◽  
Electrical Heating ◽  
Temperature Perturbation ◽  
Energy Propagation ◽  
Numerical Predictions ◽  
Supercritical Carbon

Thermoacoustic waves in near-critical supercritical carbon dioxide are investigated experimentally on acoustic time scales using a fast electrical heating system along with high speed pressure measurements. Supercritical carbon dioxide (near the critical or the pseudocritical states) in an enclosure is subjected to fast boundary heating with a thin nickel foil and an R-C circuit. The combination of very high thermal compressibilities and vanishingly small thermal diffusivities of the near-critical fluid affect the thermal energy propagation, leading to the formation of acoustic waves as carriers of thermal energy (the so called piston effect). The experimental results show that under the same temperature perturbation at the boundary, the strength of the acoustic field is enhanced as the initial state of the supercritical fluid approaches criticality. The heating rate, at which the boundary temperature is raised, is a key factor in the generation of these acoustic waves. The effect of different rates of boundary heating on the acoustic wave formation mechanism near the critical point is studied. The thermoacoustic wave generation and propagation in near-critical supercritical fluid is also investigated numerically and compared with the experimental measurements. The numerical predictions show a good agreement with the experimental data.

Supercritical carbon dioxide extraction of β-carotene and α-tocopherol from pumpkin: a Box–Behnken design for extraction variables

2017 ◽  
Vol 9 (2) ◽  
pp. 294-303 ◽  
Author(s):  
Xiudong Wang ◽  
Chen Wang ◽  
Xianjun Zha ◽  
Yanan Mei ◽  
Jingxin Xia ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Supercritical Carbon Dioxide ◽  
Supercritical Fluid Extraction ◽  
Supercritical Fluid ◽  
Supercritical Carbon Dioxide Extraction ◽  
Fluid Extraction ◽  
Box Behnken Design ◽  
Carbon Dioxide Extraction ◽  
Β Carotene ◽  
Supercritical Carbon

In this study, supercritical fluid extraction with carbon dioxide was applied to achieve a successful extraction of both β-carotene and α-tocopherol from pumpkin.

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