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Temperature Behavior (temperature + behavior)

Distribution by Scientific Domains

Polymers and Materials Science	33%

Selected Abstracts

Cold flow properties of fuel mixtures containing biodiesel derived from animal fatty waste

EUROPEAN JOURNAL OF LIPID SCIENCE AND TECHNOLOGY, Issue 9 2006
Kiril Kazancev
Abstract The aims of the present study were to evaluate the cold temperature behavior of methyl esters of vegetable and animal origin and of their mixtures with fossil diesel fuel, as well as to investigate the effectiveness of different depressants. Various blends of rapeseed oil methyl esters, linseed oil methyl esters, pork lard methyl esters and fossil diesel fuel were prepared, and both cloud point and cold filter plugging point (CFPP) were analyzed. It was found that mixtures with CFPP values of ,5,°C and lower may contain up to 25% of pork lard methyl esters; whereas the ratio of summer fossil diesel fuel and rapeseed oil methyl esters may vary over a wide range, i.e. such mixtures can be used in a diesel engine in the summer. In the transitory periods it is possible to use up to 20% animal and vegetable ester blends (3,:,7) with winter fossil diesel, whereas only up to 5% of esters can be added to the fuel used in winter. In order to improve the cold properties of rapeseed oil, pork lard and linseed oil methyl ester mixtures, various additives were tested. Depressant Viscoplex 10,35 with an optimal dose of 5000,mg/kg was found to be the most effective. [source]

Flow Behavior of Sandwich Structures for Cooling Thermally Highly Loaded Steam Turbine Components,

ADVANCED ENGINEERING MATERIALS, Issue 5 2009
Paul Beiss
To increase steam temperature and pressure in the steam turbine, a new cooling structure (see picture) was developed comprising a woven wire mesh interlayer between two plane sheets. Cooling steam is fed into the interlayer, where it can flow without severe losses. To characterize the mechanical high temperature behavior of the structure, the flow behavior under static loading was investigated and simulated by the finite element method (FEM). [source]

Effects of host mineral re-equilibration during uplift and cooling on the fidelity of primary hydrothermal fluid inclusions: a theoretical example using Mississippi Valley-type ore fluids

GEOFLUIDS (ELECTRONIC), Issue 2 2009
M. A. McKIBBEN
Abstract At the moment of its trapping as a primary fluid inclusion, a hydrothermal fluid is typically at or near equilibrium with multiple mineral species at depth and temperature. After trapping, however, the isolated inclusion fluid can re-equilibrate only with its own host mineral species during later uplift and cooling to surface conditions. Because the solubility versus temperature behavior is unique for each host mineral species, identical inclusions trapped at the same time within different species may re-equilibrate in a disparate manner upon cooling and become variably less representative of the original trapped fluid once they reach ambient temperature. To test the significance of this effect, a series of theoretical equilibrium reaction models was constructed in which a trapped hydrothermal fluid characteristic of Mississippi Valley-type ore deposits is cooled in contact with silicate, sulfide and carbonate hosts, respectively, from 100 to 25°C. Dissolved base metal concentrations are predicted to decline by two to four orders of magnitude in inclusions in all hosts, due to the precipitation of optically undetectable masses of sulfide daughter minerals. Fluids in the calcite host show the greatest decline in dissolved base metals upon cooling, due to its retrograde solubility and consequent shift in the pH and aqueous C speciation of the fluid. ,13C values for CO2 in all hosts become depleted by 2,7, relative to the original trapped fluid, with depletions again being the greatest for the calcite host due to its retrograde dissolution. Analytical techniques that extract and analyze the complete contents of fluid inclusions at room temperature can account for the predicted precipitation of microscopic daughter minerals during cooling, but may not compensate for chemical changes caused by the retrograde dissolution of calcite. Such solubility effects are another reason to be cautious in using carbonate minerals for fluid inclusion studies, in addition to their undesirable physical properties of softness, deformability and perfect cleavage. [source]

Dielectric Response of Aramid Fiber-Reinforced PEEK

MACROMOLECULAR CHEMISTRY AND PHYSICS, Issue 16 2002
Nina Korbakov
Abstract Dielectric spectroscopy was applied for the first time to aramid fiber-reinforced PEEK, wherein the effect of the fiber on the dielectric response was examined for both amorphous and crystalline poly(ether ether ketone) (PEEK) over wide temperature and frequency ranges. Whereas the temperature behavior of the dielectric losses of the materials exhibited the typical , and , processes of PEEK, the specific effect of the fibers in the crystalline PEEK was revealed in shifting the , process to a higher temperature. The unique effect of the fibers was expressed by a significantly higher activation energy and lower dielectric strength for the , relaxation, reflecting a higher constraint level that is imposed by the fiber. It is proposed that this additional constraint is associated with fiber generated transcrystallinity. Scanning electron micrograph of transverse fracture surface of crystallized unidirectional aramid fiber-reinforced PEEK. [source]

Burning Behavior of Nitramine Gun Propellants under the Influence of Pressure Oscillations

PROPELLANTS, EXPLOSIVES, PYROTECHNICS, Issue 3 2010
Gert Pauly
Abstract By means of DNDA nitramine fractions in the formulation, it is hoped to produce gun propellants that have an almost temperature-independent burning behavior. The reason for this behavior is not clear yet. In the last years, it has become known that pressure oscillations may occur in the hole channels of gun propellant grains that may lead to a modification of the burning. To analyze the impact of such oscillations on the burning behavior of DNDA powders, tests with two different DNDA powders were performed in a closed vessel. In both cases, it could be demonstrated that the oscillations have a determining influence on the temperature behavior. [source]

Investigation of the localization effect in InGaNAs/GaAs SQWs using the LSE model

PHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 1 2010
Esmaeil Abdoli
Abstract In this paper, the temperature behaviors of photoluminescence (PL) spectra of as-grown and annealed InGaASN/GaAs single quantum-well (SQW) samples with different nitrogen levels have been investigated by means of the localized-state ensemble (LSE) model. The variations of PL peak position and linewidth versus temperature are attributed to the creation of a fluctuation potential in the band edge of the host material from the nonuniform distribution of nitrogen in the structure. The anomalous thermal behaviors have been investigated by using the LSE model and a good agreement between experimental and theoretical results has been observed, especially at low temperature. The LSE model predicts a reduction of the localized states in rapid thermal annealed (RTA) samples compared to the as-grown state. [source]