Abdelkader Outzourhit

Development of absolute hot-wire anemometry by the 3ω method

We have developed hot-wire anemometry applying the 3omega method. The approach is based on the same heat transfer process as traditional anemometry, but substituting the constant current by a sinusoidal current and using synchronous detection to measure the conductive-convective exchange coefficient and the gas flow rate. Our theoretical model is tested with air flow at 300 K under atmospheric pressure: The experimental results are in agreement with the numerical simulation, justifying the technical choices in the 3omega method and the approximations made. The effectiveness of the 3omega method for measuring the flow rate and the conductive-convective exchange coefficient between the hot wire and flowing gas is discussed.

Infrared and Raman Study of Amorphous Silicon Carbide Thin Films Deposited by Radiofrequency Cosputtering

ABSTRACT Amorphous silicon carbide thin films have been deposited by radiofrequency cosputtering. These films were deposited from a composite target consisting of silicon fragments regularly distributed on the surface of a pure graphite disc for different relative silicon-to-carbon area ratio values (15%, 25%, 35%, 50%, and 65%), with a radiofrequency power of 250 watts. Structural properties of these films were investigated by Fourier transform infrared and Raman spectroscopy techniques. The infrared absorption spectra obtained on as-deposited films show the presence of two absorption bands, which are assigned to vibrational modes of silicon–carbon and silicon–oxygen bonds. The content of silicon–carbon bonds increases with increasing the relative silicon-to-carbon area ratio from 15% to 35% and then decreases for greater values. The maximum value of silicon–carbon bonds’ content, occurring at about the relative silicon-to-carbon area ratio equal to 35%, indicates that this surface ratio value leads to the formation of nearly stoichiometric silicon carbide. The Raman spectroscopy measurements show that all the as-deposited films are amorphous and contain not only silicon–carbon bonds but also silicon–silicon and/or carbon–carbon bonds (sp3and sp2). The silicon-rich films contain mainly silicon bonds, while the carbon-rich ones contain mainly carbon bonds. The maximum content of silicon–carbon bonds for the relative silicon-to-carbon area ratio equal to 35% is confirmed by Raman results.

Synthesis, annealing, characterization, and electronic properties of thin films of a quaternary semiconductor; copper zinc tin sulfide

ABSTRACT Copper zinc tin sulfide thin films were successfully prepared by spin coating on Molybdenum-coated glass substrates. The as-deposited thin films were annealed at 400°C, 450°C, and 500°C in an Argon atmosphere for 1 hr. X-ray diffraction studies revealed that the thin films present the kësterite phase. The band gap decreased with increasing annealing temperature. Schottky barrier-type structures were fabricated and showed a rectifying behavior. The estimated values of the barrier height, the built-in voltage, and the doping density were, respectively, ΦB = 0.71 eV, Na = 5 × 1018 cm−3, and Vbi = 0.33 V for annealed films.

Structural, Optical, and Electrical Characteristics of Zinc Oxide and Copper Oxide Films and Their Heterojunctions

In this paper, n-Zinc oxide/p-copper oxide heterojunctions were fabricated by RF-sputtering on indium tin oxide-covered glass substrates. The structural and optical properties of the copper oxide and zinc oxide films were analyzed by X-ray diffraction, Fourier transform infrared, scanning electronic microscopy and ultraviolet-visible spectroscopy. The electrical junction properties were investigated by current–voltage (I–V) characteristics. Additionally, both capacitance (C) and conductance (G) versus frequency (f) measurements were realized at room temperature. The junctions showed a rectifying behavior, and C and G varied with both voltage and frequency.

Structural, Optical, and Electrical Properties of Kësterite/Zinc Oxide Heterostructures

ABSTRACT In this work, kësterite thin films were deposited on soda lime glass substrates by spin coating from a sol-gel precursor without further sulfurization. Zinc oxide films were prepared by an electrochemical technique, and these films were then used to fabricate kësterite/zinc oxide heterojunc-tions. X-ray diffraction analysis showed that the as-deposited kësterite films were poorly crystallized with the presence of binary metal sulfides. Annealing in vacuum greatly enhanced the crystalline of the films and eliminated the binary phases. The properties of kësterite/zinc oxide junctions were analyzed by current voltage as well as capacitance and conductance versus applied voltage and frequency measurements. The current voltage characteristics exhibited a rectifying behavior. On the other hand, the capacitance of the junction changed with frequency, suggesting the presence of deep states within the junction.

Mathematical Models Calculating PV Module Temperature Using Weather Data: Experimental Study

A portion of solar irradiance that reaches the surface of the Photovoltaic modules is transformed into heat, and this increases the temperature of the modules which causes a decrease in their performance. As a result, the evaluation of the Photovoltaic modules temperature has a great importance. In this study, we give an overview of different approaches for Photovoltaic module temperature prediction by comparing different theoretical models with experimental measurements. These temperature models are calculated using meteorological parameters such as environment temperature, incident solar irradiance and wind speed if necessary. Data collected from three grid-connected Photovoltaic systems based on three technologies: Monocrystalline, Polycrystalline and Amorphous are used in this work. The different results obtained in this study are: It is not obvious to give one formula correlation to describe all the modules temperatures behaviours. Models without wind effect gave the best simulations for the three technologies. Lasnier and PVsyst methods gave the best results, NOCT approach has overestimated the module temperature; among the models without wind. Akhsassi2 and Sandia correlations gave satisfying results while Mattei has overestimated the module temperature; among the models considering wind effect.

Modeling of a Single Effect Evaporation desalination process using a Micro-CSP plant

This paper presents the modeling of a Single Effect Evaporation (SEE), and the potential of its integration with a micro-CSP plant, as a case study for the integration of Micro-CSP for the generation of industrial process heat. First the performance of the solar collector is evaluated for for different solar tracking systems with one and two axes. This is followed by modeling a SEE system in steady-state operation. The effect of the important design and operating parameters controlling the production of fresh water is investigated, This system was implemented in TRNSYS environment [1]. The simulations were performed over a day through TMY weather file in Marrakech [2].

Fabrication and characterization of inverted hybrid solar cells based on conducting polymers and nanostructured Zinc oxide

The hybrid conducting polymers/inorganic semiconductor is an important alternative for low-cost solar cells. Poly(o-toluidine) (POT) thin films were fabricated by spin coating technique on ZnO seed layer and on ZnO nanowires from a solution of poly(o-toluidine) in chloroform. The optical, the structural and morphological properties of the as-deposited materials were measured, presented and discussed. ITO/ZnO(buffer)/POT/Al and ITO/ZnO(buffer)/ZnO nanowires/POT/Al optoelectronic devices were fabricated. The current-voltage characteristics of these devices were measured in the dark and under illumination and indicated a photovoltaic activity.

Dielectric properties of Alumina based nanofluids

The alumina (Al2O3) with different morphologies have great interest due to their potential use in various technological areas such as as-catalysis, batteries, solar energy conversion, gas sensing and field emission. In this work, nanostructured Al2O3 were prepared by a solution-phase method in the presence of ethylene glycol (EG) as a dispersant and growth-directing agent. Nanofluids were obtained by dispersing controlled amounts of these nanoparticles in ethylene glycol. The dielectric properties of the obtained nanofluids were measured in the frequency range 40 Hz and 100 kHz using a specially designed cell with two stainless steel cylindrical electrodes. The conductance and the capacitance of Al2O3-based nanofluid increase with the mass fraction and always stay higher than that of pure EG.