To decrease CO2 accumulation in air to alleviate global warming, efficient utilization of energy and effective utilization of renewable biomass resources are required. Coal has received attention as a suitable fossil fuel energy source because of its evenly distributed rich deposits. However, CO2 emission from burning coal is extremely high (1800-2410 g/kg). Novel methods that decrease environmental loading are therefore highly sought-after. In this context, the operation of the following three methods is currently under survey: (1) integrated coal gasification combined cycles by which a power plant can be operated at high efficiency, above 50%, (2) gasification technologies for biomass; and (3) establishment of a method for the use in advanced chemical applications. This scientific review introduces the forefront of these three methods and explicates fundamental phenomena of gasification.
Heat treatment is one of the upgrading technologies for biomass benefication. The torrefaction process, which means low temperature heat treatment of woody biomass around 250 - 320 ℃ without oxygen atmosphere, has recently emerged as a promising technology to upgrade biomass fuel characteristics. Torrefied woody biomass fuel holds higher energy density than conventional charcoal, and better hydrophobicity and requires lower grinding energy than wood chip and pellet. One of the usage of torrefied fuels is co-firing with coal in large scale power generation plant, where the co-firing ratio can be greatly increased in the case of the torrefied fuel. Also, there is possibility to use as fuel for the heating appliance in small scale. Characterization of heat-treated biomass fuel is generally similar to that of coal, while there are some differences in determinations of ash content, ash fusion behavior, sieving and so on. However, most of the characterization methods have been published as international standards. The stakeholders dealing with solid biomass fuels in Japan shall strongly contribute to discuss the international standards.
Almost all solid state materials are deteriorated by several factors such as oxygen, heat, water, light, radiation and so on. These deteriorations will cause the unexpected disasters. Therefore, it is important that reaction rates and heats of deterioration for solid state materials are investigated. Recently, biocoke is investigated as an effective fuel. Biocoke has some excellent features of high density, high strength, no water absorption and no fermentation. However, heat behaviors of biocoke which is storage under the several environments are not known well. In this report, some heat flux curves of deteriorations of biocoke from 298.15 K to 323.15 K were measured by using micro-calorimeter (TAM II). Then, these curves were fitted by zero order reaction rate equation, α = kt, and reaction rate constants, k, were calculated. The activation energies of deterioration of biocoke were calculated from these reaction rate constants by using Arrhenius equation. Moreover, a half lives of biocoke for measurement temperatures were estimated from reaction rate constants. These results will be reported in detail.
This paper aims to measure the drag acting on a racing car model designed and made by students in Miyakonojo College, National Institute of Technology (KOSEN) and to visualize flow fields around the model by means of Particle Image Velocimetry (PIV) and Computational Fluid Dynamics (CFD). Large Eddy Simulation (LES) model for CFD is adopted to simulate turbulent flows around and behind the model. Flow separation on the model top-roof and longitudinal vortices at the model sidewalls are demonstrated in detail by the PIV visualization and are confirmed by the simulation. Separation frequency obtained from the simulation is processed by the fast Fourier transformation (FFT) of the velocity, clarifying that the frequency increases according to a power law of Reynolds number. The coalescence of the separation vortices and the longitudinal ones behind the model are demonstrated by the simulation, indicating that a negative pressure region generated by the coalescence of these vortices largely affects the aerodynamics drag of the model. The drag coefficient evaluated from the measured drag is compared with that obtained from the simulation, the latter of which is expressed in the form of a power law of Reynolds number. The results obtained suggest suitable positions of plasma actuator (PA) to be installed on the model for flow control.
Biomass is well known as one of the carbon neutral and renewable energy resources. Bio-coke, hereinafter called BIC, is one of the solid biomass fuel which can be made from various woody or herbaceous biomass by heating and compressing process. BIC is expected to be an alternative of coal coke because of its high hardness and high density characters. In the present study, the carbonization characteristics of the BIC were investigated experimentally. Three settings of carbonization procedures were examined and weight yield, volumetric shrinkage, specific weight, ratio of components and compressive strength were measured. As a result, it was found that BIC does not collapse during the carbonization process unlike common pellets and briquettes when heating rate is properly controlled and the carbon yield is higher than that of the carbonization of wood. In addition, the physical strength of the carbonized BIC decreased with carbonization temperature increased when the carbonization temperature was less than 873 K while it improved with carbonization temperature when the carbonization temperature was more than 873 K.
One of the problems that hinder the spread of woody biomass is the melting of combustion ash. This is a big issue in home stoves. Unlike other woody biomass solid fuels, it is suggested that the combustion ash of Bio-coke is difficult to melt. Therefore, it is necessary to produce small-diameter Bio-coke of a size that can be applied to wood pellet fired home stoves, and to elucidate the melting mechanism of combustion ash and research for effective utilization of combustion ash. In this research, in order to improve the production ability of small-diameter Bio-coke, it worked on the improvement of the batch-type production process using a six-holed molder. (1) It was found that the size per piece can be increased by 78% by optimizing the initial moisture content. (2) It was found that the production ability per unit time could be improved by about 50-90% by shifting the production process using two molding units. (3) From the above results, it was found that the production efficiency can be improved 2.6-3.3 times that of the initially designed production system.
To utilize chip fuel such as wood chips and hog fuel widely in the industrial sector, the dimension property has to be reformed. In this study, pyrolysis treatment is conducted prior to crushing. The aim of this study is to investigate the effect of pyrolysis treatment and crushing methods on the dimension property of chip fuel. The biomass samples used in experiments are stemwood without bark and bark of Japanese cedar. The range of pyrolysis temperature is 200-500 deg. C, and two crushing devices are used, hammer mill and cutter mill. After crushing, the height h, the long side l and the short side s of chip fuel are measured, and three aspect ratios, l/s, l/h and s/h are evaluated. The ratio l/h is the largest among the three aspect ratios for each experiment. The ratio l/h for hammer mill is larger than that for cutter mill. As the pyrolysis temperature increases, the ratio l/h decreases rapidly in the temperature range between 200 and 300 deg. C. From the experimental results, it is found that the optimum pyrolysis temperature to produce chip fuel with low aspect ratio below five or six is around 250 and 350 deg. C for stemwood without bark and bark, respectively.
Homogenization of water temperature is important for quality control of a towing tank. Measurements of the vertical distribution of water temperature in a towing tank and its evaluation of homogenization by water circulation are carried out. The circulation affects the measurement of the towing tank using ship model, thus the velocity of water is commonly measured. From the measurements and discussions, it is found that 1) recognition of the characteristics of the towing tank and the equipment are important and 2) circulation of water is important because water temperature near the surface is strongly affected by room temperature.
In fracture evaluation in regions other than head in forensic engineering, dummy skin that reproduces load of propagating human soft tissue has been used. However, conventional dummy skins often have narrow velocity range that can be applied in incident or accident, and are not used very often. Therefore, there is the need for dummy skin that can be used in wider velocity range. In this paper, we focused on super soft urethane resin (SSUR) which can be expected to be used as dummy skin in wider velocity range. Furthermore, regarding the load when external force was transmitted to bone, the effectiveness of SSUR was examined by comparing with soft tissue and conventional dummy skin. As a result, it was confirmed that SSUR can be used in wider velocity range than conventional dummy skin. In addition, since propagation load for impact velocity in SSUR was similar to that in soft tissue, it became clear that this could be used as dummy skin in various velocities. Furthermore, since the effect of thickness on propagating load in SSUR was similar to that in soft tissue, it became clear that it could be used as dummy skin for fracture evaluation in individuals and regions.
Active control of motion of microbubbles by using electric or magnetic fields is experimentally investigated. Cationic surface active agent was dissolved to water to add positive electric charge to the surface of the microbubbles. These electrified microbubbles are successfully moved by artificially applied electric field to direction of the negative electrode. Magnetic particles were further adhered to the surface of the electrified microbubbles to add magnetism to the microbubbles. These magnetized microbubbles are successfully moved towards electro magnet. Control of microbubbles that flow with water stream in bifurcating channel are attempted next. By placing positive and negative electrodes at both side of the bifurcating channel, the electrified microbubbles are successfully guided through one side of the channel. The magnetized microbubbles are also able to be guided through the one side of the channel by electro magnet that is placed at the bifurcation of the channel. From the above, it is confirmed that the motion of microbubbles can be actively controlled by electric and magnetic fields.