scholarly journals Influence of Colour Filter on Reaction Products from Mo and W Heated to 2000°C by Concentrated Solar Beam in N2 Gas Environment in a Solar Furnace at PROMES-CNRS

2011 ◽  
Vol 52 (11) ◽  
pp. 2083-2090 ◽  
Author(s):  
Gilles Peraudeau ◽  
Fernando Almeida Costa Oliveira ◽  
Luís Guerra Rosa ◽  
Bernard Granier ◽  
Jorge Cruz Fernandes ◽  
...  
Keyword(s):  
Solar Furnace ◽  
Colour Filter ◽  
Reaction Products ◽  
Gas Environment

Experimental Investigation of an Atmospheric-Open Cyclone Solar Reactor for Solid-Gas Thermochemical Reactions

1992 ◽  
Vol 114 (3) ◽  
pp. 171-174 ◽  
Author(s):  
A. Steinfeld ◽  
A. Imhof ◽  
D. Mischler
Keyword(s):  
Absorption Efficiency ◽  
Solar Furnace ◽  
Small Scale ◽  
Reaction Products ◽  
Concentrated Solar Energy ◽  
High Temperature Process ◽  
Energy Absorption Efficiency ◽  
Particle Separator ◽  
Solar Receiver ◽  
High Degree

A solar receiver-reactor has been designed to conduct solid-gas chemical reactions, using concentrated solar radiation as the energy source of high-temperature process heat. It consists of a conical cyclone gas-particle separator that has been modified to let concentrated solar energy enter the cavity through a windowless (atmospheric-open) aperture. It combines the advantages of cavity receivers and volumetric reactors, and permits continuous mode of operation. A small-scale prototype reactor to conduct the thermal decomposition of calcium carbonate at 1300 K was experimentally investigated in a solar furnace. Its thermal performance was evaluated. The mean energy absorption efficiency, based on the optically measured power incident on the receiver aperture, was 43 percent. Reaction products showed high degree of calcination.

Experimental Investigation of a Vortex-Flow Solar Chemical Reactor for the Combined ZnO-Reduction and CH4-Reforming*

2001 ◽  
Vol 123 (3) ◽  
pp. 237-243 ◽  
Author(s):  
Stefan Kra¨upl ◽  
Aldo Steinfeld
Keyword(s):  
Heat Transfer ◽  
Vortex Flow ◽  
Solar Power ◽  
Radiation Heat Transfer ◽  
Chemical Conversion ◽  
Chemical Reactor ◽  
Solar Furnace ◽  
Reaction Products ◽  
Ch4 Reforming ◽  
Reactor Operating

The co-production of Zn and synthesis gas by the combined reduction of ZnO and reforming of CH4 has been performed using a vortex-flow chemical reactor in a high-flux solar furnace. The reactor operating temperature ranged between 1221 and 1481 K for an input solar power of 2.3 to 4.6 kW and mean solar flux intensities of 810 to 1609 kW/m2. The performance of the reactor was determined by conducting a complete mass and energy balance for the chemical process. The chemical conversion ranged between 83–100 percent. The thermal efficiency, defined as the portion of input solar power absorbed as sensible and process heat, was in the range 11–28 percent. The exergy efficiency for the closed cycle, defined as the ratio of the maximum amount of work that the products leaving the reactor could produce if were re-combined to the input solar power, was in the range 0.3–3.1 percent. Major sources of energy loss are re-radiation heat transfer through the reactor aperture, conduction heat transfer through the reactor walls, and the quenching of the reaction products.

scholarly journals Crystal Grain Morphology Evolution over Ti, V, Nb and Ta Surface Heated in N2 Gas Environment to 2000°C by Filtered Concentrated Solar Beam in a Solar Furnace at PROMES-CNRS

2012 ◽  
Vol 53 (3) ◽  
pp. 537-545 ◽  
Author(s):  
Fernando Almeida Costa Oliveira ◽  
Luís Guerra Rosa ◽  
Gilles Peraudeau ◽  
Bernard Granier ◽  
Jorge Cruz Fernandes ◽  
...  
Keyword(s):  
Grain Morphology ◽  
Solar Furnace ◽  
Morphology Evolution ◽  
Gas Environment

scholarly journals Synthesising Carbo-Nitrides of some D-Group Transition Metals Using a Solar Furnace at PSA

2012 ◽  
Vol 730-732 ◽  
pp. 153-158 ◽  
Author(s):  
Nobumitsu Shohoji ◽  
Fernando A. Costa Oliveira ◽  
Luis Guerra Rosa ◽  
José Cruz Fernandes ◽  
Teresa Magalhães ◽  
...  
Keyword(s):  
Single Phase ◽  
Solar Furnace ◽  
Processing Temperature ◽  
Transition Elements ◽  
X Ray Diffraction ◽  
X Ray ◽  
Carbide Phases ◽  
Group Metal ◽  
Gas Environment ◽  
Ar Gas

Carbo-nitride synthesis was undertaken using a solar furnace at PSA in flowing N2/Ar gas mixture under total pressure 1 atm and processing temperatureT= 1600°C for some d-group transition elements (Ti; Zr, V, Nb, Mo, W) starting from 1.5G/M (graphite/metal powder mixture with mole ratio 1.5:1) compact to ensure co-presence of free carbon with the reaction product. Clear X-ray diffraction (XRD) evidence of formation of carbo-nitride was detected for Ti (IVa group metal) showing higher N content in the carbo-nitride synthesised in N2gas environment at partial pressurep(N2) = 1 atm than that atp(N2) = 0.5 atm. For M = V and Nb (Va group metals), formation of mono-carbide MC single-phase was detected in the N2environment showing no evidence of formation of carbo-nitride in spite of presence of N2in the environment. For M = Mo and W (VIa group metals), formation of higher carbide, among several options of carbide phases, appeared to be promoted in the N2gas environment although, like in cases with the Va group metals, no evidence of dissolution of N into the reaction product was detected. As such, atT= 1600°C in N2gas environment up top(N2) = 1 atm under concentrated solar beam, carbo-nitride formed from the 1.5G/M mixture only for IVa group metal (Ti) but not for Va and VIa group metals. Anyway, it seemed certain that N2gas affected somehow the reaction path between G and M to yield the carbide phase for M = V, Nb, Mo and W.

scholarly journals Influence of Gas Environment on Synthesis of Silicon Carbide through Reaction between Silicon and Amorphous Carbon in a Solar Furnace at P. S. A. (Plataforma Solar de Almería)

1998 ◽  
Vol 106 (1236) ◽  
pp. 839-841 ◽  
Author(s):  
Jorge CRUZ FERNANDES ◽  
Luís GUERRA ROSA ◽  
Diego MARTÍNEZ ◽  
José RODRIGUEZ ◽  
Nobumitsu SHOHOJI
Keyword(s):  
Silicon Carbide ◽  
Amorphous Carbon ◽  
Solar Furnace ◽  
Gas Environment

scholarly journals Treatment of Molybdenite Ore Using a 2 kw Solar Furnace

1979 ◽  
Author(s):  
S. R. Skaggs ◽  
J. P. Coutures
Keyword(s):  
Department Of Energy ◽  
Solar Furnace ◽  
Reaction Products ◽  
Crossover Point ◽  
Cooperative Effort ◽  
Organic Vapors ◽  
The Us ◽  
Temperature Ranges ◽  
Scientific Laboratory ◽  
Molybdic Oxide

Hydrometallurgical methods of extracting molybdenite (MoS2) from the raw ore consume 145 × 106 Btu ton of fossil fuel equivalent energy per ton of concentrate produced. Processing the ore using a solar heat source could save 56 percent of this energy. Thermodynamic considerations indicate that MoS2 is the easiest of the economically valuable ores to extract. If the technique can be developed with this ore, it may be possible to extend it to other ores. Oxidation of the sulfide to molybdic oxide (MoO3) is an exothermic process, and it should proceed autogenically if the concentration of MoS2 is high enough. Experiments to measure the specific heat of the raw ore were conducted to determine the crossover point for this autogenic reaction. Using a calorimeter, we found three distinct reaction temperature ranges corresponding to water and organic vapors, oxidation of pyrite (FeS2), and oxidation of molybdenite. The production rate of SO2 was measured for 0.5-g samples of three different concentrations of molybdenite: (a) 95 percent MoS2 concentrate, (b) 10 percent concentrate in the raw ore, and (c) the unadulterated raw ore. A crude mass balance was obtained between the reaction products and the unreacted ore in the hearth. The curves of reacted product wersus time look very similar to the curves of SO2 gas produced versus time. Both sets of curves show the reaction is more than 90 percent complete in one minute. This work is sponsored by the US Department of Energy and the French Center Nationale de Recherche Scientifique. It is a cooperative effort of the Los Alamos Scientific Laboratory in the US and the Laboratoire des Ultra-Refractaires and the Laboratoire d’Energetique Solaire in Odeillo, France.

Experimental Investigation of a Vortex-Flow Solar Chemical Reactor for the Combined ZnO-Reduction and CH4-Reforming

2001 ◽  
Author(s):  
Stefan Kräupl ◽  
Aldo Steinfeld
Keyword(s):  
Heat Transfer ◽  
Vortex Flow ◽  
Solar Power ◽  
Radiation Heat Transfer ◽  
Chemical Conversion ◽  
Chemical Reactor ◽  
Solar Furnace ◽  
Reaction Products ◽  
Ch4 Reforming ◽  
Reactor Operating

Abstract The co-production of Zn and synthesis gas by the combined reduction of ZnO and reforming of CH4 has been performed using a vortex-flow chemical reactor in a high-flux solar furnace. The reactor operating temperature ranged between 1032 and 1481 K for an input solar power of 2.3 to 4.6 kW and mean solar flux intensities of 810 to 1609 kW/m2. The performance of the reactor was determined by conducting a complete mass and energy balance for the chemical process. The chemical conversion ranged between 83–100%. The thermal efficiency, defined as the portion of input solar power absorbed as sensible and process heat, was in the range 11–28%. The exergy efficiency for the closed cycle, defined as the ratio of the maximum amount of work that the products leaving the reactor could produce if were re-combined to the input solar power, was in the range 0.3–3.1%. Major sources of energy loss are re-radiation heat transfer through the reactor aperture, conduction heat transfer through the reactor walls, and the quenching of the reaction products.

Lead aspartate: a new en bloc stain for electron microscopy

1978 ◽  
Vol 36 (2) ◽  
pp. 34-35
Author(s):  
J.R. Walton
Keyword(s):  
Electron Microscopy ◽  
Calcium Ion ◽  
Enzyme Reaction ◽  
Lead Citrate ◽  
Reaction Products ◽  
En Bloc ◽  
Thin Sections ◽  
Lead Salts ◽  
Thin Sectioning ◽  
High Alkalinity

In electron microscopy, lead is the metal most widely used for enhancing specimen contrast. Lead citrate requires a pH of 12 to stain thin sections of epoxy-embedded material rapidly and intensively. However, this high alkalinity tends to leach out enzyme reaction products, making lead citrate unsuitable for many cytochemical studies. Substitution of the chelator aspartate for citrate allows staining to be carried out at pH 6 or 7 without apparent effect on cytochemical products. Moreover, due to the low, controlled level of free lead ions, contamination-free staining can be carried out en bloc, prior to dehydration and embedding. En bloc use of lead aspartate permits the grid-staining step to be bypassed, allowing samples to be examined immediately after thin-sectioning.Procedures. To prevent precipitation of lead salts, double- or glass-distilled H20 used in the stain and rinses should be boiled to drive off carbon dioxide and glassware should be carefully rinsed to remove any persisting traces of calcium ion.

Studies of Oxide Formation on Copper Thin Films by Electron Microscopy

1977 ◽  
Vol 35 ◽  
pp. 316-317
Author(s):  
G. G. Hembree ◽  
M. A. Otooni ◽  
J. M. Cowley
Keyword(s):  
Electron Microscopy ◽  
Electron Diffraction ◽  
Single Crystal ◽  
Crystal Surface ◽  
Crystal Defects ◽  
Diffraction Reflection ◽  
Reaction Products ◽  
Intermediate Energies ◽  
Crystal Films ◽  
Reflection Electron Microscopy

The formation of oxide structures on single crystal films of metals has been investigated using the REMEDIE system (for Reflection Electron Microscopy and Electron Diffraction at Intermediate Energies) (1). Using this instrument scanning images can be obtained with a 5 to 15keV incident electron beam by collecting either secondary or diffracted electrons from the crystal surface (2). It is particularly suited to studies of the present sort where the surface reactions are strongly related to surface morphology and crystal defects and the growth of reaction products is inhomogeneous and not adequately described in terms of a single parameter. Observation of the samples has also been made by reflection electron diffraction, reflection electron microscopy and replication techniques in a JEM-100B electron microscope.A thin single crystal film of copper, epitaxially grown on NaCl of (100) orientation, was repositioned on a large copper single crystal of (111) orientation.

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