Waste treatment in Japan has been conducted mainly by incineration for the purpose of ensuring proper treatment. On the other hand, recently in Europe, there is a tendency to promote incineration for the purpose of reducing landfill and thermal recycling. Introducing the approach to environmental problems in incinerator, efforts to suppress generation using reaction simulation for fuel-NOx in combustion chamber, and efforts to use agricultural fertilizer as an extension of slag applications in melting system. In waste treatment, it is necessary to optimize the entire process in consideration of regional characteristics and economic efficiency for a series of processes such as generation, collection, intermediate treatment (e.g. incinerator), and landfill.
The main goal of our laboratory is to contribute to society through technological development related to solving global environmental problems. We aim to develop basic technologies that lead to the CO2 emissions reduction and the realization of a sustainable recycling society. For example, Research and development on environment-conscious technologies such as bioremediation, and CO2 utilization technologies using bioprocesses are underway. Although such research and development is not directly linked to architecture and civil engineering business of construction company, it is considered an important approach from the viewpoint of the internationally recognized sustainable development goals (SDGs).
Alumina balls initially placed on the flat bottom wall of a water-filled vessel were agitated by a vertically impinging water jet to crush fly ash particles. A part of the alumina balls was removed from the impingement point to a certain extent. A circular region without any balls was formed on the bottom wall. Only the balls located just outside the perimeter of the circle were found to be moving continuously. Such a restricted region is responsible for the crush of fly ash and, hence, for the size adjustment of fly ash particles. The diameter of the circular region and the area of the restricted region were measured. Meanwhile, when a water jet is introduced into the bath along the curved side wall of the vessel, a semi-ellipsoidal region without alumina balls was formed on the bottom wall of the vessel. The area responsible for fly ash crush was nearly the same as generated by the submerged vertical impinging water jet. From a practical point of view, an unsteady impinging water jet is superior to the above-mentioned steady water jets.
Heat transport devices using temperature-sensitive magnetic fluids are fast to start, have high heat transfer efficiency, and can be downsized. In addition, it has the advantage that it is not affected by the installation posture compared to conventional heat transport equipment. In order to apply a temperature-sensitive magnetic fluid to a heat transport device, it is necessary to clarify the heat flow characteristics of this fluid. However, since the ferromagnetic particles in the fluid are black and fine, observation with a microscope was difficult. In this study, the microcapsules contain a temperature-sensitive magnetic fluid, which enables fluorescence observation. Capsules were made by mixing a temperature-sensitive fluid, polymer, organic solvent, and fluorescent dye and dispersing in pure water mixed with a surfactant. Microcapsule aqueous solutions have been shown to have properties similar to magnetic fluids. When this solution was flowing, it was confirmed that when a magnetic field was applied, clusters were formed near the wall and a unique velocity distribution was formed. It was confirmed that as the solution temperature increased, the possibility of cluster formation decreased.
The behavior of an acrylic sphere falling in water contained in a vertical circular pipe subjected to bottom air injection was observed with a video camera and by eye inspection. The flow patterns of air-water two-phase flows thus generated include the bubbly and slug flow regimes. The wettability of the sphere was changed by coating a water repellent material on its surface. The contact angle of the original acrylic sphere was 71° and that of the poorly wetted one was 143°. The terminal velocity of the sphere was measured to make clear the effects of the flow pattern and the wettability of the sphere on the velocity.
Greening technology in the manufacturing has been developed extensively. Currently, with the IoT technology development and the improvement of computing power, the development of methods for improving energy efficiency of the entire manufacturing system, not individual devices, has become active. In such a situation, we aim to high efficiency of the energy consumption in the system by optimizing the cutting conditions of machine tools from the viewpoint of the entire system. In this study, a manufacturing system consisting of multiple machine tools was used as a test bed, and it was verified whether the peak demand value could be reduced by changing the machining speed of one machine tool. The appropriate processing speed was determined based on the power consumption model constructed by simple preliminary experiments. As a result of numerical simulation based on the measured values, the peak demand value in the entire manufacturing system was reduced by an appropriate machining speed. By determining the processing conditions using the power consumption model, efficiency of the energy consumption in the entire manufacturing system was improved.
This paper attempts to seek the possibility for computationally estimate the mixing time of jet-induced rotary sloshing against the previous experimental result. Simulation technique employed in this study includes Computational Fluid Dynamics (CFD). Results for occurrence process and the period of the sloshing are successfully verified against our previous results. A lot of solid particles are then injected into the container as a tracer and tracked every time step for estimating the mixing time computationally. The particles injected move in the bath due to the hydrodynamic force, the added-mass force, the buoyancy force and the own weight, and the positions of the particles can be updated by solving the equation of motion of the particles with the use of a one-way coupling. For a low flow-rate condition of the inlet jet, the resulting computational mixing time is in agreement with the experimental result, introducing a short-time average of the particle dispersion ratio that successfully removes high frequency components in the signals.
For the development of a vertical axis turbine, the elucidation research of the mechanism related to the fluid engineering operation of the turbine plays an important role. As a solution to the problem of improving the startability of the lift type turbine, a combined type or a hybrid type using a drag type has been proposed. The torque component in the lift generated by the blade is important for realizing the startability and performance improvement. If attention is paid to the blade element, the direction of the lift line due to the deflection of the surrounding flow field is one of important factors. In other words, the adoption of a Savonius type drag turbine for the reason that the performance is excellent alone is meaningless. The author devised a drag turbine with a cylinder with improved starting torque and hybridized it with a straight blade Darius turbine. In this report, the performance characteristic of a hybrid turbine is considered in relation to the flow field generated by an inner drag turbine.
In recent years, environmental pollution caused by suspended sludge and milliplastics has become serious in the environmental pollution problem caused by floating garbage in the coast and in the bay. In particular, aquaculture by hypoxia due to eutrophication in the bay is a factor that deteriorates productivity. Therefore, in this study, we proposed a structure of a floating vertical axis wind turbine that can be towed by mooring and ships. We report the results of a basic experiment on the behavior of a floating body and the performance of a helical pump for the purpose of a system that absorbs and processes more.
After a big earthquake and subsequent accidents at Fukushima Dai-ichi Nuclear Power Plant (NPP) in March 2011, the NPPs in Japan have been shutdown, and the power shortage has been compensated by Thermal Power Plants (TPPs). Such changes in the power generation mix would have affected air quality in the Osaka area. In this study, we estimated the change in the emission amount of pollutants from TPPs and evaluated the influence on photochemical ozone under typical midsummer conditions using a numerical model. By the shutdown of NPPs, NOx emitted from general electricity utilities became about two times larger in Kansai, Hokuriku and Shikoku areas. By the TPPs substitution photochemical ozone decreased in the middle of the Osaka plain and increased in the surrounding areas. This tendency is consistent with the photochemical regime we previously estimated. Observation showed similar result; however, the changes in ozone concentration were much larger than our model results possibly due to VOC reduction from other sources. The increase of TPP emission does not influence strongly on the photochemical ozone in the objective area. It is much more important to discuss it from the viewpoint of global warming.
Galvannealed iron-zinc Alloy sheet is one of the main steel products for automotive. In surface inspection of GA steel strip by camera system with image processing, detection of low contrast defects due to metal oxide inclusions that are beneath the surface layer is an important issue. In case a highly sensitive inspection, slight oil adhesion causes error detection, because both the defect portion and the oil portion have comparable reflective intensities in a normal optical system. However, originally, the reflectance of oil is sufficiently smaller than that of GA, and the reason is unknown that the reflective intensity of oil portion is so high as to obstruct inspection. In this report, we analyzed the microstructure of the oil portion and its reflective characteristics, and clarified the reason why it becomes an obstacle to the inspection with comparable contrast to that of defects.
In order to address the energy-saving and the recent environmental problems such as global warming due to CO2 emissions, continuous efforts are required to improve the performance of the steam turbines and the gas turbines, which support the base of energy conversion. With the aim of reducing the secondary flow losses within the highly loaded turbine cascade, the authors have proposed a new idea to install the plasma actuators on the inlet wall of the turbine cascade. To realize the high-performance concept, experimental investigations to clarify the vortex structure near the enwall of a cascade by using smoke wire technique and PIV as a laser measurement system were carried out. And also, CFD using LES model were conducted to analyze the vortices system in detail by comparing experimental results with calculation. As a result, formation and development of the horseshoe vortex and the passage vortex within the highly loaded turbine cascade became clear through the streaks of smoke generated by the wire, velocity vectors obtained from PIV measurement and LES analysis.