Summary of studies of the η meson production with polarized proton beam at COSY‐11
We report on the COSY‐11 measurements of the analysing power for the pp→ppη reaction and interpret the results in the framework of the meson exchange models.
POLARIZATION PHENOMENA IN NUCLEAR REACTIONS.
The recent appearance of high-intensity polarized beams with a small energy spread has made feasible a number of experiments which could not have been considered just a few years ago. In many reactions, polarization parameters can often be measured almost as easily as cross sections. The volume of experimental data can thus be expected to increase rapidly; the results should be precise and reliable. The problem of explaining the measurements and drawing from them all the information about nuclear structure and nuclear reaction mechanisms that they contain is likely to severely challenge standard reaction theories.
Effect of superficial gas velocity on the particle temperature distribution in a fluidized bed with heat production
The heat transfer behavior of particles and gas in an olefin polymerization fluidized bed was numerically analyzed using an in-house developed 3-D computational fluid dynamics discrete element model (CFD-DEM). First the implementation of the model was verified by comparing simulation results with analytical results. A constant volumetric heat production rate was implemented in the particle energy equation to mimic the heat production due to the polymerization reaction. It was found that the probability density function (PDF) of the particle temperature becomes more homogeneous with increasing superficial gas velocity. Furthermore, instantaneous snapshots of the thermal driving force (the difference between the single particle temperature and bed-average gas temperature, Tp− ) for different heat production rates provide detailed insight in the particle temperature distribution inside the fluidized bed. The time- and bed-averaged particle convective heat transfer coefficient, which was calculated by Gunn׳s correlation, was found to be independent of the superficial gas velocity. This is explained by the fact that the relative velocity of gas and particles in the emulsion phase, where most of the particles and gas interact, is hardly influenced when increasing the gas superficial velocity. From the spatial distribution of Nusselt number, it becomes apparent that the high heat transfer regions are found in the wake of rising bubbles, whereas low heat transfer rates are found in the clouds of the bubbles.