Dense phase pneumatic conveying in a pipeline is often applied to avoid disadvantage such as high power consumption, particle breakage and pipeline abrasion. This article described mainly the dense phase pneumatic conveying in a horizontal rectangular channel using the fluidizing air. The fluidized powder conveying system consists of a powder supply vessel and a horizontal rectangular channel at the side of vessel. The powder was fluidized by air through the porous membrane at the bottom of a vessel and a horizontal channel. The powder used belongs to Geldart A particle, where the mean diameter is 53 μm, the particle density is 2523kg/m³ and the minimum fluidizing velocity is 4.329mm/s. The mass of transported powder, the bed height of powder in a vessel and the supply air pressure were measured when the fluidizing velocities at the bottom of vessel and horizontal channel were changed. The powder could be transported smoothly when the air was supplied to the bottom of vessel and the velocity of the bottom of horizontal channel exceeded the minimum fluidizing velocity. In this case, the powder was discharged smoothly from vessel to horizontal channel, and then the powder flowed easily toward the exit of horizontal channel. Therefore, the fluidizing air at the bottom of vessel and horizontal channel was important to obtain smooth powder conveying on this system. Also, the mass flow rate of powder and the solid loading ratio were estimated from the mass of transported powder against the elapsed time. As the result, the solid loading ratio had taken a one peak when the fluidizing velocity at the bottom of horizontal channel was larger than the minimum fluidizing velocity. In addition, it is found from the analyzed solid loading ratio that the high dense powder conveying was possible in this system.

抄録全体を表示

The particles emitted from diesel engine exhaust have low resistive in nature and extremely small in the range of 70-120 nanometers. These particles are penetrated into an alveolus and extremely harmful to human health. These particles are generated from various emissions such as diesel automobiles, marine engines, power generation engines, and construction diesel machines. These particulates also exist in tunnel or underground parking. An electrostatic precipitator has been extensively used for the collection of these particles. In the present technical report, the technology of electrostatic precipitator on diesel exhaust particle was explained.

抄録全体を表示

Moisture transport is an important phenomenon in many technological fields. We summarize a fundamental description method with use of the relative permeability and the moisture diffusion coefficient. The theoretical approach for the two-phase flow in the porous media is based on the extended Darcy model. The relative permeability and the moisture diffusion coefficient are functions of the moisture content and they express the effects of the friction loss and the capillary pressure, respectively. The model is applied to the microwave vacuum drying of food, where the vapor pressure drives the moisture from the inner to the outer because of the internal heating by the microwave irradiation. The numerical moisture-distributions are compared with the experimental results obtained by the MRI. It is shown that the microwave vacuum drying gives a desirable moisture-distribution for the drying.

抄録全体を表示

Gas-liquid and liquid-liquid multiphase flows are often encountered in application of microreactors. When two immiscible fluids are introduced to a microchannel, several flow patterns may be observed depending on the fluid property, flow conditions, and the channel geometry. Slug flow is the most important flow mode among them, because the mass transfer rate across the fluid interface is greatly enhanced. The enhancement of the mass transfer was attributed to the recirculating flow within each slug, which promotes the mass transfer from the fluid interface to the interior of each slug. Thus, it is important to clarify the range of operating conditions in which slug flow can be formed. Also, to fully understand the mass transfer enhancement in slug flow regime, the fluid behavior in each slug must be studied. Many studies have been conducted to construct a general flow regime map. Also, the fluid flow within a slug has been investigated by utilizing flow visualization techniques and computational fluid dynamics simulations. This article gives an brief overview of the studies on the characteristics of multiphase flow in microchannels.

抄録全体を表示

Supercritical carbon dioxide is expected as a solvent in nano-scale material preparations, such as rapid expansion of supercritical solutions (RESS), supercritical anti-solvent (SAS) precipitation, and supercritical solvent impregnation (SSI) due to the unique properties of carbon dioxide, non toxic, inflammable, and mild critical temperature and pressure 304.2 K and 7.3 MPa, respectively. In this work, the ophthalmic drug delivery systems were prepared by SSI method using carbon dioxide. The effects of water in SSI process on the drug release profile from the prepared drug delivery system were investigated. The knowledge of the solid-liquid-gas equilibria is very important for the process design in SSI process. The prediction model of the solid-liquid-gas in supercritical carbon dioxide mixture are also developed by using the equation of state combined with the molecular information, molecular surface charge density, surface area, and volume obtained from the quantum calculations.

抄録全体を表示

This paper demonstrates numerical simulations of droplet on/in gas diffusion layer of the polymer electrolyte fuel cell. The lattice Boltzmann method for incompressible two-phase flows at high density ratios were applied for the simulations in order to predict the shape and moving velocity of water droplet surrounding by the air in the gas channel. In addition to the simulation, droplet infiltration to the simulated gas diffusion layer were simulated. The droplet heights by the simulations were qualitatively agreed with the experimental data, while the simulation results of moving speed of droplet somewhat overestimated the experimental results.

抄録全体を表示

This paper shows Pipeline Sediment Transportation using HSRS ( Hydro-Suction sediment Removal Systems ) which is one of countermeasures for removable sedimentation in a dam reservoir. Since HSRS can also use power other than water head, it is the technology in which expansion of scopes, such as not only dam reservoirs but river channel, a seashore region, etc., is expectable. This paper is reported about the function of pipeline sediment transportation. Therefore, it reexamined about experiment data from a viewpoint of sediment discharge and flow state of sediment in a pipe-line.

抄録全体を表示

Oil spill response requires multiphase flow techniques in various aspects. Among them, methods for treating water-in-oil emulsion, which is often formed when oil spills on the sea surface, are very important. W/O emulsion drastically increases its viscosity and makes oil recovery operation very difficult. This paper presents friction loss reduction techniques in a pipeline flow as well as rheological behavior of the emulsion. For friction reduction, water injection and chemical surfactant injection were experimentally studied. It was found that the both methods can reduce the friction loss to a considerable extent. They were applied to practical use for oil recovery vessels.

抄録全体を表示

TEPCO announced that the safety relief valves of the Fukushima Daiichi NPP Unit 1 were never manually opened during the accident due to the shortage of DC power. However, the measured reactor pressure was about 1MPa at 2:43 of March 12. At that moment the core damage must already start due to almost no core injection for nearly 11 hours while the reactor vessel bottom head must not fail according to the severe accident analyses so far. Such unanticipated depressurization might accelerate the core “uncovery” and also prevent early containment failure caused by the direct containment heating. The authors modeled the creep failures of the stainless steel guide tubes of the source range monitor (SRM) in the reactor core and the main steam line. Based on such failure models, the possible depressurization mechanism of the Unit 1 and related phenomena were estimated using a severe accident analysis code SAMPSON. The estimated scenario by this study is that the creep failures of the SRM dry tubes failed first and caused the leakage from the core to the containment while the direct cause of the depressurization is the creep failure of the main steam line after the start of core damage.

抄録全体を表示

In this study, the rising velocity of Taylor bubbles in inclined tube was investigated. In the experiment, the air-water two-phase flow system equipped with the Taylor bubble injector, which can inject arbitrary size Taylor bubble with a certain distance, was used. The inclined angle was 30-90 degree, the tube inner diameter was 20mm, the dimensionless bubble diameter λ was 0.6-2.0 and liquid velocity was 0.011-0.053m/s. As the result, the influence of the tube inclination and bubble size on the correlation for the bubble velocity with the separation distance of two consecutive bubbles was presented. On the basis of these results, the characteristics of the Taylor bubble movements were explained. Moreover, the fundamental data of two consecutive bubbles, i.e. the maximum trailing bubble velocity, the location of maximum velocity, the effective range of velocity and the damping ratio of velocity were reported.

抄録全体を表示