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Full-Text Articles in Thermodynamics
Gibbs Dividing Surface And Helium Adsorption, Sasidhar Gumma, Orhan Talu
Gibbs Dividing Surface And Helium Adsorption, Sasidhar Gumma, Orhan Talu
Chemical & Biomedical Engineering Faculty Publications
All adsorption data is based on the definition of Gibbs dividing surface, which is a purely mathematical transformation. Adsorption measurements in microporous solids necessitate experimental determination of the dividing surface. An international protocol does not exist on how to perform this important measurement. Commonly, helium is assumed not to adsorb and used as a probe molecule for this measurement. Each experimentalist chooses an arbitrary set of conditions, often without even disclosing them, which adds to the confusion in adsorption literature. Here, a self-consistent method for the analysis of helium data is proposed which does not assume non-adsorbing helium …
Molecular Simulation Of Adsorption: Gibbs Dividing Surface And Comparison With Experiment, Orhan Talu, Alan L. Myers
Molecular Simulation Of Adsorption: Gibbs Dividing Surface And Comparison With Experiment, Orhan Talu, Alan L. Myers
Chemical & Biomedical Engineering Faculty Publications
At low temperature near the normal boiling point, computer simulations of adsorption of gases can be compared directly with experiment. However, for adsorptive gas separations in which the gas is adsorbed near or above its critical temperature, absolute simulation variables must be converted to excess variables for comparison with experiment. The conversion of absolute to excess variables requires the helium pore volume of the adsorbent. Lennard-Jones potential parameters for helium gas molecules interacting with the oxygen atoms of silicalite are ε/k = 28.0 K and σ = 2.952 Å. The helium pore volume of silicalite is 0.175 cm …
Editorial, Orhan Talu, Shivaji Sircar
Editorial, Orhan Talu, Shivaji Sircar
Chemical & Biomedical Engineering Faculty Publications
No abstract provided.
Copper Alloy-Impregnated Carbon-Carbon Hybrid Composites For Electronic Packaging Applications, S. K. Datta, Surendra N. Tewari, Jorge E. Gatica, W. Shih, L. Bentsen
Copper Alloy-Impregnated Carbon-Carbon Hybrid Composites For Electronic Packaging Applications, S. K. Datta, Surendra N. Tewari, Jorge E. Gatica, W. Shih, L. Bentsen
Chemical & Biomedical Engineering Faculty Publications
Porous carbon-carbon preforms, based on three-dimensional networks of PAN (Polyacrylonitrile)-based carbon fibers and various volume fractions of chemical vapor-deposited (CVD) carbon, were impregnated by oxygen-free, high-conductivity (OFHC) Cu, Cu-6Si-0.9Cr, and Cu-0.3Si-0.3Cr (wt pct) alloys by pressure infiltration casting. The obtained composites were characterized for their coefficient of thermal expansion (CTE) and thermal conductivity (K) along the through-thickness and two in-plane directions. One composite, with a 28 vol pct Cu-0.3Si-0.3Cr alloy, showed outstanding potential for thermal management applications in electronic applications. This composite exhibited approximately isotropic thermal expansion properties (CTE = 4 to 6.5 ppm/K) and thermal conductivities (k greater than …
Behavior And Performance Of Adsorptive Natural Gas Storage Cylinders During Discharge, K. J. Chang, Orhan Talu
Behavior And Performance Of Adsorptive Natural Gas Storage Cylinders During Discharge, K. J. Chang, Orhan Talu
Chemical & Biomedical Engineering Faculty Publications
Adsorbed natural gas (ANG) has the potential to replace compressed natural gas in mobile storage applications, such as in vehicles. Although a substantial research effort has been devoted to ANG, very few studies evaluate the impact of heat of adsorption on system performance. This paper concentrates on the impact of heat of adsorption on ANG performance during discharge, while the gas outflow rate is dictated by the energy demand of the application. The temperature drop and performance loss was measured with commercially available ANG cylinders under realistic conditions. Data show as high as a 37°C temperature drop at …
Activity Coefficients Of Adsorbed Mixtures, Orhan Talu, Jianmin Li, Alan L. Myers
Activity Coefficients Of Adsorbed Mixtures, Orhan Talu, Jianmin Li, Alan L. Myers
Chemical & Biomedical Engineering Faculty Publications
Experimental and simulated data for adsorption of gas mixtures on energetically heterogeneous surfaces like activated carbon and zeolites exhibit negative deviations from ideality. The deviations are large in some cases, with activity coefficients at infinite dilution equal to 0.1 or less. Similar molecules form ideal mixtures, but molecules of different size or polarity are nonideal. Equations for bulk liquid mixtures (Wilson, Margules, etc.) do not apply to isobars for adsorbed mixtures. A two-constant equation for activity coefficients as a function of composition and spreading pressure is in good agreement with theory, simulation, and experiment.
Dendrite Spacings In Directionally Solidified Superalloy Pwa-1480, M. Vijayakumar, Surendra N. Tewari, James E. Lee, P. A. Curreri
Dendrite Spacings In Directionally Solidified Superalloy Pwa-1480, M. Vijayakumar, Surendra N. Tewari, James E. Lee, P. A. Curreri
Chemical & Biomedical Engineering Faculty Publications
Primary dendrite spacings and side-branch coarsening kinetics were examined in specimens of the single-crystal multicomponent commercial superalloy PWA-1480, which were directionally solidified in a positive thermal gradient. The experimentally observed dependence of primary dendrite spacings and side-branch coarsening kinetics on growth rate and thermal gradient were in agreement with the behavior predicted by analytical models developed for binary alloys.