Hideki Tokanai

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.