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RISS 인기검색어
- 검색키워드
- 저자 : W.R. Rossen (검색결과 3 건)
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Effect of temperature on foam flow in porous media
L. Kapetas,S. Vincent Bonnieu,S. Danelis,W.R. Rossen,R. Farajzadeh,A.A. Eftekhari,S.R. Mohd Shafian,R.Z. Kamarul Bahrim 한국공업화학회 2016 Journal of Industrial and Engineering Chemistry Vol.36 No.-
Foam can increase sweep efficiency within a porous medium, which is useful for oil-recovery processes[1]. The flow of foam in porous media is a complex process that depends on properties like permeability,porosity and surface chemistry, but also temperature. Although the surface activity of surfactants as afunction of temperature is well described at the liquid/liquid or liquid/gas interface, data on the effect oftemperature on foam stability is limited, especially in porous media. In this work, we tested a surfactant (AOS) at different temperatures, from 20 8C to 80 8C, in asandstone porous medium with co-injection of foam. The pressure gradient, or equivalently the apparentviscosity, was measured in steady-state experiments. The core-flood experiments showed that theapparent viscosity of the foam decreased by 50% when the temperature increased to 80 8C. This effectcorrelates with the lower surface tension at higher temperatures. These results are compared to bulkfoam experiments, which show that at elevated temperatures foam decays and coalesces faster. Thiseffect, however, can be attributed to the faster drainage at high temperature, as a response to thereduction in liquid viscosity, and greater film permeability leading to faster coarsening. Our results using the STARS foam model show that one cannot fit foam-model parameters to data atone temperature and apply the model at other temperatures, even if one accounts for the change in fluidproperties (surface tension and liquid viscosity) with temperature. Experiments show an increase in gasmobility in the low-quality foam regime with increasing temperature that is inversely proportional tothe decrease in gas-water surface tension. In the high-quality regime, results suggest that the watersaturation at which foam collapses fmdry increases and Pc* decreases with increasing temperature.
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Electric modulation of conduction in multiferroic Ca-doped BiFeO<sub>3</sub> films
Yang, C.-H.,Seidel, J.,Kim, S. Y.,Rossen, P. B.,Yu, P.,Gajek, M.,Chu, Y. H.,Martin, L. W.,Holcomb, M. B.,He, Q.,Maksymovych, P.,Balke, N.,Kalinin, S. V.,Baddorf, A. P.,Basu, S. R.,Scullin, M. L.,Rames Nature Publishing Group 2009 Nature materials Vol.8 No.6
Many interesting materials phenomena such as the emergence of high-Tc superconductivity in the cuprates and colossal magnetoresistance in the manganites arise out of a doping-driven competition between energetically similar ground states. Doped multiferroics present a tantalizing evolution of this generic concept of phase competition. Here, we present the observation of an electronic conductor–insulator transition by control of band-filling in the model antiferromagnetic ferroelectric BiFeO<SUB>3</SUB> through Ca doping. Application of electric field enables us to control and manipulate this electronic transition to the extent that a p–n junction can be created, erased and inverted in this material. A ‘dome-like’ feature in the doping dependence of the ferroelectric transition is observed around a Ca concentration of ∼1/8, where a new pseudo-tetragonal phase appears and the electric modulation of conduction is optimized. Possible mechanisms for the observed effects are discussed on the basis of the interplay of ionic and electronic conduction. This observation opens the door to merging magnetoelectrics and magnetoelectronics at room temperature by combining electronic conduction with electric and magnetic degrees of freedom already present in the multiferroic BiFeO<SUB>3</SUB>.
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S.A. Jones,G. Laskaris,S. Vincent-Bonnieu,R. Farajzadeh,W.R. Rossen 한국공업화학회 2016 Journal of Industrial and Engineering Chemistry Vol.37 No.-
We present a comparative study of foam coreflood experiments with various surfactant concentrations. Plots of apparent viscosity vs. injected gas fraction were obtained for surfactant concentrations at thecritical micelle concentration and above. Bulk foam stability was measured for all concentrations andcompared with the coreflood results. There were different responses to surfactant concentration in bulkand in corefloods. The coreflood results were matched with an implicit-texture foam model, and the dependency of themodel parameters on the surfactant concentration is discussed. Fitting the data requires relating thesurfactant concentration to the dry-out function or the limiting capillary pressure.
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