Thermal Modelling and Experimental Comparison for a Moving Pantograph Strip
This paper proposes a thermal study of the catenary/pantograph interface for a train in motion. A 2.5D complex model of the pantograph strip has been defined and created by a coupling between a 1D and a 2D model. Experimental and simulation results are presented and with a comparison allow validating the 2.5D model. Some physical phenomena are described and presented with the help of the model such as the stagger motion thermal effect, particular heats and the effect of the material characteristics. Finally it is possible to predict the critical thermal
configuration during a train trip.
Thermal wear and electrical sliding wear behaviors of the polyimide modified polymer-matrix pantograph contact strip
In the present study, the polyimide resin (PI)/cashew-modified resin (YM) polymer-matrix pantograph contact strip (PMPCS) was prepared by using hot repressing, hydro-solidification and dipping treatment processes. The thermal properties of cured resins were studied by thermogravimetry analyzer and differential scanning calorimetry. The thermal wear and electrical sliding wear behaviors of PMPCS against copper were evaluated by a ring block wear tester at elevated temperature under dry sliding conditions and a wear tester which simulated the train motion under laboratory conditions, respectively. Worn surfaces and wear debris of PMPCS were analyzed by scanning electron microscopy and energy dispersive spectrometer, and the wear mechanism was discussed. It has been found that the thermal stability of the PI/YM is superior to that of the YM under the same testing conditions. The results also showed that PI/YM-PMPCS had superior wear resistance than that of YM-PMPCS at elevated temperature and with electrical current. At elevated temperature, the wear mechanism of tribological pair evolved from adhesive wear to oxidative wear with mild delamination wear. Arc erosion wear, oxidative wear, and adhesive wear were the dominant mechanisms of tribological pair during the electrical wearing process.
Microfiltration: Effect of retentate protein concentration on limiting flux and serum protein removal with 4-mm-channel ceramic microfiltration membranes.
The objective of our study was to determine if the limiting flux and serum protein (SP) removal were different at 8, 9, or 10% true protein (TP) in the microfiltration (MF) retentate recirculation loop using 0.1-µm ceramic graded permeability membranes with 4-mm-channel diameters operated at 50 °C using a diluted milk protein concentrate with 85% protein on a total solids basis (MPC85) as the MF feed. The limiting flux for the MF of diluted MPC85 was determined at 3 TP concentrations in the recirculation loop (8, 9, and 10%). The experiment was replicated 3 times for a total of 9 runs. On the morning of each run, MPC85 was diluted with reverse osmosis water to an MF feed TP concentration of 5.4%. In all runs, the starting flux was 55 kg/m(2) per hour, the flux was increased in steps until the limiting flux was reached. The minimum flux increase was 10 kg/m(2) per hour. The limiting flux decreased as TP concentration in the recirculation loop increased. The limiting flux was 154 ± 0.3, 133 ± 0.7, and 117 ± 3.3 kg/m(2) per hour at recirculation loop TP concentrations of 8.2 ± 0.07, 9.2 ± 0.04, and 10.2 ± 0.09%, respectively. No effect of recirculation loop TP concentration on the SP removal factor was detected. However, the SP removal factor decreased from 0.80 ± 0.02 to 0.75 ± 0.02 as flux was increased from the starting flux of 55 kg/m(2) per hour to the limiting flux, with a similar decrease seen at all recirculation loop TP concentrations.