Toshio Oshima

Estimation of the Co-ordination number in a Multi-Component Mixture of Spheres

Abstract A simple model of a 2-component mixture of spherical- or disk-type particles was proposed for estimating the co-ordination number, which is the number of contact points on a particle. To verify the validity of the model, the co-ordination numbers calculated from the model were compared with those obtained from the computer simulation of a 2-component mixture and there was fairly good agreement between the two sets of data. An extention of the model was made to calculate the effect of multi-component spherical particles on the co-ordination number. The model gives a good approximation to the existing experimental data for 4- and 5- component mixtures.

Co-ordination number of a multi-component randomly packed bed of spheres with size distribution

Abstract Multi-component randomly packed beds of spheres with log—normal, log—uniform, Rosin—Rammler and Andreasen (Gaudin—Schuhmann) size distributions are made by computer simulation, and the relation between the co-ordination numbers and the size distributions are investigated. From these results, it is clear that the co-ordination number for each sphere deviates from the value for a uniform-sized sphere bed with the expansion of size distribution, but an average co-ordination number is found close to 6 which is the value for a uniform-sized sphere bed, and independent of the type and expansion of size distribution. Furthermore, these results are compared with the estimated values calculated from the model, and fairly good agreement is demonstrated between the two sets of data.

The effect of the types of mill on the flowability of ground powders

It is empirically known that the flowability of ground powders varies with the types of mill. In this study, five kinds of test powders of the same size made from the same raw material were prepared by five different types of mills and classifiers. The flowability of these powders was measured and the difference between each result identified. Then, the relationship between the flowability of the powder and particle shape was investigated. The circularity, Wadells working sphericity, the fractal dimension of particle perimeters and the specific surface area ratio of the test powders were measured, and the effect of the particle shape on the flowability index was studied. The result was that the particle shape, especially the surface roughness of particles, had a very great effect on the flowability of the powders produced in different types of mill.

Calculation Method for Air Cooled Exchanger with Water Spray

空冷熱交換器に水を噴霧させると伝熱面上を濡らした水滴の蒸発が起こるため, 空冷単独の場合に比べ伝熱量が増加し, 装置を小型化できる。伝熱面であるブイン付管上での熱と物質の同時移動現象を解析的に取り扱い, 空気は水蒸気で飽和された状態で温度変化すると仮定して, 冷却凝縮器に対する三点簡略法の計算手法を適用した設計法を提案した。計算値は実験結果をよく説明できるので, この方法が充分設計に役立つものと考える。

Calculation on Finned Tube Cooler Condensers

フィン付管冷却凝縮器のフィン効率算出法としン部気液界面条件が飽和蒸気圧曲線を厳密にたどる符合の計算を行なつたが, 伝熱面積算出値は前報の簡略計算法により求めた値とほとんど同じなので, フィン効率算出法は前報の方法て充分であると考える。さらに縦フイン付管冷却凝欄と横フィン付管冷却凝縮器はる実験結果と計算値がよく一致したので, 前報によるフィン効率算出法を基礎としたフィン付管冷却凝縮器の設計充分実用性があると考えてよい。