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Full-Text Articles in Engineering
Wear And Friction Behavior Of Metal Impregnated Microporous Carbon Composites, Gultekin Goller, D. P. Koty, Surendra N. Tewari, M. Singh, A. Tekin
Wear And Friction Behavior Of Metal Impregnated Microporous Carbon Composites, Gultekin Goller, D. P. Koty, Surendra N. Tewari, M. Singh, A. Tekin
Chemical & Biomedical Engineering Faculty Publications
Metal-matrix composites have been prepared by pressure-infiltration casting of copper-base alloy melts into microporous carbon preforms. The carbon preforms contained varying proportions of amorphous carbon and graphite. Load dependence of the wear and friction behavior of the composite pins has been examined under ambient conditions against cast-iron plates, using a pin-on-plate reciprocating wear tester. The wear resistance of the composite is significantly improved, as compared with the base alloy. Contrary to the normally expected behavior, the addition of graphite to the amorphous carbon does not reduce the friction coefficient, especially at high loads. The wear and friction behavior of the …
Permeability Of Microporous Carbon Preforms, S. K. Datta, N. Simhai, Surendra N. Tewari, Jorge E. Gatica, M. Singh
Permeability Of Microporous Carbon Preforms, S. K. Datta, N. Simhai, Surendra N. Tewari, Jorge E. Gatica, M. Singh
Chemical & Biomedical Engineering Faculty Publications
The permeability of microporous amorphous carbon preforms with varying pore size and pore distributions has been experimentally examined. The porous structures have been characterized by mercury porosimetry and by quantitative metallography of pressure-infiltration-cast metal matrix composites based on the carbon preforms. The permeability shows a linear correlation with the fraction porosity and the square of the pore diameter.
Measurement And Analysis Of Oxygen/Nitrogen/5a-Zeolite Adsorption Equilibria For Air Separation, Orhan Talu, Jianmin Li, Ravi Kumar, Paul M. Mathias, J. Douglas Moyer Jr, Joan M. Schork
Measurement And Analysis Of Oxygen/Nitrogen/5a-Zeolite Adsorption Equilibria For Air Separation, Orhan Talu, Jianmin Li, Ravi Kumar, Paul M. Mathias, J. Douglas Moyer Jr, Joan M. Schork
Chemical & Biomedical Engineering Faculty Publications
Multicomponent adsorption equilibrium data are essential for the reliable design of processes and equipment for gas separation by adsorption. We discuss techniques for the measurement and analysis of multicomponent adsorption equilibrium data, and present a comprehensive set of equilibrium data for the adsorption of oxygen and nitrogen on 5A-zeolite.
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 …
Macrosegregation During Dendritic Arrayed Growth Of Hypoeutectic Pb-Sn Alloys: Influence Of Primary Arm Spacing And Mushy Zone Length, Surendra N. Tewari, Rajesh Shah
Macrosegregation During Dendritic Arrayed Growth Of Hypoeutectic Pb-Sn Alloys: Influence Of Primary Arm Spacing And Mushy Zone Length, Surendra N. Tewari, Rajesh Shah
Chemical & Biomedical Engineering Faculty Publications
Thermosolutal convection in the dendritic mushy zone occurs during directional solidification of hypoeutectic lead tin alloys in a positive thermal gradient, with the melt on the top and the solid below. This results in macrosegregation along the length of the solidified samples. The extent of macrosegregation increases with increasing primary dendrite spacings for constant mushy zone length. For constant primary spacings, the macrosegregation increases with decreasing mushy zone length. Presence of convection reduces the primary dendrite spacings. However, convection in the interdendritic melt has significantly more influence on the spacings as compared with that in the overlying melt, which is …
Convection During Thermally Unstable Solidification Of Pb-Sn In A Magnetic Field, Hui Song, Surendra N. Tewari, H. C. Degroh Iii
Convection During Thermally Unstable Solidification Of Pb-Sn In A Magnetic Field, Hui Song, Surendra N. Tewari, H. C. Degroh Iii
Chemical & Biomedical Engineering Faculty Publications
Convection and macrosegregation in directionally solidified hypoeutectic Pb-38 wt pct Sn and hypereutectic Pb-64.5 wt pct Sn have been examined during upward and downward growth. Temperature fluctuations are observed along the length of the melt column during downward growth. With increasing Rayleigh number, these fluctuations change from none, to cyclic, to time periodic having multiple harmonics, and finally to random. At the higher convective driving force of 350 K temperature inversion, the transverse magnetic field decreased convective levels, strong random temperature fluctuations (flows) becoming smaller and periodic. The maximum field of 0.45 T was unable to completely eliminate convection. For …
Time Dependence Of Tip Morphology During Cellular Dendritic Arrayed Growth, Hui Song, Surendra N. Tewari
Time Dependence Of Tip Morphology During Cellular Dendritic Arrayed Growth, Hui Song, Surendra N. Tewari
Chemical & Biomedical Engineering Faculty Publications
Succinonitrile-1.9 wt pct acetone has been directionally solidified in 0.7 X 0.7-cm-square cross section pyrex ampoules in order to observe the cell/dendrite tip morphologies, not influenced by the ''wall effects,'' which are present during growth in the generally used thin (about 200 mu m) crucibles. The tips do not maintain a steady-state shape, as is generally assumed. Instead, they fluctuate within a shape envelope. The extent of fluctuation increases with decreasing growth speed, as the micro structure changes from the dendritic to cellular. The influence of natural convection has been examined by comparing these morphologies with those grown, without convection, …
The Influence Of Acoustic Impedance Mismatch On Post-Stenotic Pulsed-Doppler Ultrasound Measurements In A Coronary Artery Model, S. A. Jones, H. Leclerc, George P. Chatzimavroudis, Y. H. Kim, N. A. Scott, Ajit P. Yoganathan
The Influence Of Acoustic Impedance Mismatch On Post-Stenotic Pulsed-Doppler Ultrasound Measurements In A Coronary Artery Model, S. A. Jones, H. Leclerc, George P. Chatzimavroudis, Y. H. Kim, N. A. Scott, Ajit P. Yoganathan
Chemical & Biomedical Engineering Faculty Publications
Acoustic impedance mismatch at the fluid-wall interface was shown to affect the spectra from an intravascular Doppler device in an in vitro model with a diameter typical of human coronary arteries. Measurements were obtained first under Poiseuille flow conditions with impedance mismatches of 0%, 7% and 12%, and then under stenosed conditions for the 0% and 7% mismatch cases. For the zero mismatch case, the Doppler spectra could be readily interpreted in terms of fluid mechanical phenomena. When mismatch was present, the spectra from Poiseuille flow exhibited multiple peaks which could not be directly related to the velocity profile. Also, …