The Experts below are selected from a list of 99165 Experts worldwide ranked by ideXlab platform
Aldo Steinfeld - One of the best experts on this subject based on the ideXlab platform.
-
syngas production by simultaneous splitting of h2o and co2via ceria redox reactions in a high temperature solar reactor
Energy and Environmental Science, 2012Co-Authors: Philipp Furler, Aldo Steinfeld, Jonathan R ScheffeAbstract:Solar syngas production from H2O and CO2 is Experimentally investigated using a two-step thermochemical cycle based on cerium oxide redox reactions. A solar cavity-receiver containing porous ceria felt is directly exposed to concentrated thermal radiation at a mean solar concentration ratio of 2865 suns. In the first endothermic step at 1800 K, ceria is thermally reduced to an oxygen deficient state. In the second exothermic step at 1100 K, syngas is produced by re-oxidizing ceria with a gas mixture of H2O and CO2. The syngas composition is Experimentally determined as a function of the molar co-feeding ratio H2O:CO2 in the range of 0.8 to 7.7, yielding syngas with H2:CO molar ratios from 0.25 to 2.34. Ten consecutive H2O/CO2-splitting cycles performed over an 8 hour solar Experimental Run are presented.
-
solar aluminum production by vacuum carbothermal reduction of alumina thermodynamic and Experimental analyses
Metallurgical and Materials Transactions B-process Metallurgy and Materials Processing Science, 2011Co-Authors: Michael Kruesi, Maria Elena Galvez, M Halmann, Aldo SteinfeldAbstract:Thermochemical equilibrium calculations indicate the possibility of significantly lowering the onset temperature of aluminum vapor formation via carbothermal reduction of Al2O3 by decreasing the total pressure, enabling its vacuum distillation while bypassing the formation of undesired by-products Al2O, Al4C3, and Al-oxycarbides. Furthermore, the use of concentrated solar energy as the source of high-temperature process heat offers considerable energy savings and reduced concomitant CO2 emissions. When the reducing agent is derived from a biomass source, the solar-driven carbothermal reduction is CO2 neutral. Exploratory Experimental Runs using a solar reactor were carried out at temperatures in the range 1300 K to 2000 K (1027 °C to 1727 °C) and with total pressures in the range 3.5 to 12 millibar, with reactants Al2O3 and biocharcoal directly exposed to simulated high-flux solar irradiation, yielding up to 19 pct Al by the condensation of product gases, accompanied by the formation of Al4C3 and Al4O4C within the crucible. Based on the measured CO generation, integrated over the duration of the Experimental Run, the reaction extent reached 55 pct at 2000 K (1727 °C).
Evgeniamaria Papaslioti - One of the best experts on this subject based on the ideXlab platform.
-
effects of redox oscillations on the phosphogypsum waste in an estuarine salt marsh system
Chemosphere, 2020Co-Authors: Evgeniamaria Papaslioti, Rafael Perezlopez, Annika Parviainen, Van T H Phan, Claudio Marchesi, Alejandro Fernandezmartinez, Carlos J Garrido, J M Nieto, Laurent CharletAbstract:Abstract Salt marshes are natural deposits of heavy metals in estuarine systems, where sulphide precipitation associated with redox changes often results in a natural attenuation of contamination. In the present study, we focus on the effects of variable redox conditions imposed to a highly-polluted phosphogypsum stack that is directly piled over the salt marsh soil in the Tinto River estuary (Huelva, Spain). The behaviour of contaminants is evaluated in the phosphogypsum waste and in the marsh basement, separately, in controlled, Experimentally-induced oscillating redox conditions. The results revealed that Fe, and to a lesser extent S, control most precipitation/dissolution processes. Ferric iron precipitates in the form of phosphates and oxyhydroxides, while metal sulphide precipitation is insignificant and appears to be prevented by the abundant formation of Fe phosphates. An antagonistic evolution with changing redox conditions was observed for the remaining contaminants such as Zn, As, Cd and U, which remained mobile in solution during most of Experimental Run. Therefore, these findings revealed that high concentrations of phosphates inhibit the typical processes of immobilisation of pollutants in salt-marshes which highlights the elevated contaminant potential of phosphogypsum wastes on coastal environments.
Laurent Charlet - One of the best experts on this subject based on the ideXlab platform.
-
effects of redox oscillations on the phosphogypsum waste in an estuarine salt marsh system
Chemosphere, 2020Co-Authors: Evgeniamaria Papaslioti, Rafael Perezlopez, Annika Parviainen, Van T H Phan, Claudio Marchesi, Alejandro Fernandezmartinez, Carlos J Garrido, J M Nieto, Laurent CharletAbstract:Abstract Salt marshes are natural deposits of heavy metals in estuarine systems, where sulphide precipitation associated with redox changes often results in a natural attenuation of contamination. In the present study, we focus on the effects of variable redox conditions imposed to a highly-polluted phosphogypsum stack that is directly piled over the salt marsh soil in the Tinto River estuary (Huelva, Spain). The behaviour of contaminants is evaluated in the phosphogypsum waste and in the marsh basement, separately, in controlled, Experimentally-induced oscillating redox conditions. The results revealed that Fe, and to a lesser extent S, control most precipitation/dissolution processes. Ferric iron precipitates in the form of phosphates and oxyhydroxides, while metal sulphide precipitation is insignificant and appears to be prevented by the abundant formation of Fe phosphates. An antagonistic evolution with changing redox conditions was observed for the remaining contaminants such as Zn, As, Cd and U, which remained mobile in solution during most of Experimental Run. Therefore, these findings revealed that high concentrations of phosphates inhibit the typical processes of immobilisation of pollutants in salt-marshes which highlights the elevated contaminant potential of phosphogypsum wastes on coastal environments.
M Drusch - One of the best experts on this subject based on the ideXlab platform.
-
initializing numerical weather prediction models with satellite derived surface soil moisture data assimilation experiments with ecmwf s integrated forecast system and the tmi soil moisture data set
Journal of Geophysical Research, 2007Co-Authors: M DruschAbstract:[1] Satellite-derived surface soil moisture data sets are readily available and have been used successfully in hydrological applications. In many operational numerical weather prediction systems the initial soil moisture conditions are analyzed from the modeled background and 2 m temperature and relative humidity. This approach has proven its efficiency to improve surface latent and sensible heat fluxes and consequently the forecast on large geographical domains. However, since soil moisture is not always related to screen level variables, model errors and uncertainties in the forcing data can accumulate in root zone soil moisture. Remotely sensed surface soil moisture is directly linked to the model's uppermost soil layer and therefore is a stronger constraint for the soil moisture analysis. For this study, three data assimilation experiments with the Integrated Forecast System (IFS) of the European Centre for Medium-Range Weather Forecasts (ECMWF) have been performed for the 2-month period of June and July 2002: a control Run based on the operational soil moisture analysis, an open loop Run with freely evolving soil moisture, and an Experimental Run incorporating TMI (TRMM Microwave Imager) derived soil moisture over the southern United States. In this Experimental Run the satellite-derived soil moisture product is introduced through a nudging scheme using 6-hourly increments. Apart from the soil moisture analysis, the system setup reflects the operational forecast configuration including the atmospheric 4D-Var analysis. Soil moisture analyzed in the nudging experiment is the most accurate estimate when compared against in situ observations from the Oklahoma Mesonet. The corresponding forecast for 2 m temperature and relative humidity is almost as accurate as in the control experiment. Furthermore, it is shown that the soil moisture analysis influences local weather parameters including the planetary boundary layer height and cloud coverage.
Birgit Kosjek - One of the best experts on this subject based on the ideXlab platform.
-
miser chromatography multiple injections in a single Experimental Run the chromatogram is the graph
Tetrahedron-asymmetry, 2010Co-Authors: Christopher J Welch, Edwin C Pratt, Tanja Brkovic, Zainab Pirzada, Xiaoyi Gong, Wes Schafer, James Cuff, Birgit KosjekAbstract:An Experimental approach for rapid analysis and convenient interpretation of multiparallel experiments is described. Conventional approaches use a series of individual chromatographic Runs to produce integrated peak area data, which are stored in individual data files, then transferred to a spreadsheet program and graphed to allow interpretation of Experimental results. A simpler and more direct approach utilizes multiple injections within a single chromatographic Run to produce a continuous trace of chromatograms, which can often provide a direct visual readout of Experimental outcome without the need for peak integration, data transfer, or graphing. In this approach, the chromatogram itself serves as the graph whereby the outcome of the multiparallel experiment can be discerned. The utility of the technique is greatly enhanced by the use of compound-specific detection technologies such as mass spectrometry or chiroptical spectroscopy, and can benefit from Experimental designs that facilitate the direct interpretation of results.
