Masafumi Kuriyama

The influence of particle size distribution of coal on the fluidity of coal—water mixtures

Abstract Experimental studies were carried out to investigate the influence of particle size distribution on the viscosity and maximum coal concentration in coal—water mixtures. The results show that coal—water mixtures prepared by mixing coarse and fine coal in the weight ratio of 7:3 or 6:3 possess excellent fluidity and high coal concentration. It was also discovered that it is desirable to have a large particle size difference between the coarse and fine coal in coal—water mixtures. A simple correlation method is proposed to arrange the apparent viscosity data for coal—water mixtures.

Heat Transfer of Supercritical CO2 Flow in Natural Convection Circulation System

Measurements are reported of heat transfer to supercritical carbon dioxide (SCD) flow in a natural convection circulation system that consists of a closed-loop circular pipe. Systematic data of heat transfer coefficients are given for various pressures and pipe diameters. Heat transfer coefficients of SCD flow are confirmed to be very much higher than those of usually encountered fluid flow and are shown to be expressed by a nondimensional correlation equation proposed in this work. Numerical model calculations are also presented for the velocity and temperature distributions in SCD flow to elucidate the exceedingly high value of heat transfer coefficient. The heat transfer enhancement of SCD is concluded to result from the high-speed flow near the pipe wall. This strong flow is shown to have velocity and temperature gradients steep enough to cause the enhancement of the rate of heat transfer in the vicinity of the pipe wall.

Natural‐convection heat transfer to air from a horizontal array of cylinders with different surface temperatures

Heat transfer measurements were made on natural convection around horizontal in-line arrays of cylinders whose surface temperatures were different from each other. Through the experiments for a three-cylinder array, a correlation was obtained for the heat transfer coefficient of the array-center cylinder. By using the correlation with some assumptions, the heat-flux distributions could be estimated for an array of five cylinders which were heated to their respective temperatures. Consequently, it was found that both the correlation and the method proposed here were useful in the estimation of heat-flux distributions for a horizontal array of cylinders.

Breakup Process of Highly Viscous Drops Dispersed in a Practical 50-Liter Agitated Vessel.

乳業における乳化工程について基礎的知見を得ることを目的として, ディスク有孔型後退角付ピッチドタービン翼を備えた実用50リットル撹拌槽による高粘性液滴の分散実験を行った.その結果, 操作条件をある程度変化させた時の最終滴径および過渡滴径データを得た.また, これらの滴径が小型ラシュトンタービン翼撹拌槽に関する先の研究で提案した相関式によって良好に表し得ることがわかった.

Enhancement of heat transfer from horizontal cylinder banks by use of corona wind.

水平かつ平行に置かれた円管列からの伝熱速度に及ぼすコロナ風の効果を検討した.種々の条件下でコロナ風の速度分布および最大速度を測定した.得られた結果は, コロナ風が放電々極先端から楕円形状に広がりながら吹くという仮定に基づいたモデルによって良く説明できた.このモデルを用いて各円管に吹き当たるコロナ風の平均速度を導出した.各円管の伝熱係数はこの平均速度と良好に相関することがわかり, 一様流中における単一円管の伝熱係数の相関法に従って一つの無次元相関式を提案した.

Heat transfer from parallel-horizontal cylinder rows under corona discharge.

The heat transfer coefficients of parallel-horizontal rows of cylinders which are exposed to corona discharge were measured to obtain fundamental data for practical compact heat exchangers. Three or nine cylinders of 10 mm diameter were placed horizontal and parallel at the same pitch and several discharge needle electrodes were installed along the axial direction above the central cylinder of the row. Negative high voltages were applied at the needle electrodes to generate a corona wind. It was found that an increase of the corona current increases the heat transfer coefficients of the cylinders placed in the space which is the same as the vertical minimum distance between the needle electrodes and the central cylinder of a cylinder row. The corona wind was analyzed on the basis of the momentum equation to obtain a functional formula for the heat transfer coefficient of each cylinder. It is shown that the theoretical equation correlates well all experimental data obtained for three or nine horizontal in-line cylinders.