Carbonization technology can adapt to widely and timely request regardless of age. Carbonized biomass has a lot of characteristics and functionality, porosity, water absorption, water retention, adsorption and chemical properties, electromagnetic characteristics, energy characteristic, etc. The energy crisis due to domestic circumstances and international situation is an urgent issue, and it is necessary to develop advanced technologies such as biomass utilization, carbon dioxide reduction by conversion to petroleum substitute fuels, carbon fixation. This article presents new carbonization technology and macro-micro carbonization process visualization technology due to the development of new biomass utilization. Especially, this paper will introduce the on-site observation of the microscopic carbonization process of biomass using environmental scanning electron microscopy (ESEM) ahead to new possibilities.
This study proposes an in-situ method to extract the outer surface shape of deforming thermoplastic materials during combustion. The proposed method consists of backlight photography of the burning sample which enables extraction of its shadowgraph and following filtered back-projection. Ultraviolet LED is chosen as backlight source based on a preliminary test, which shows the intensity is relatively larger than that of chemiluminescence from flame. An optical system was developed, in which the object was rotatable while the backlight and the camera were fixed. First, a draft test without burning was conducted to confirm the validity of the proposed method. A test with a burning sample was then conducted to check the applicability to extraction of the outer surface shape of the deforming object during combustion. The accuracy of the current system was evaluated for both non-burning and burning tests. The cross-sectional area obtained from the reconstructed image was compared with that obtained from design dimension of sample and that measured by a laser displacement sensor. Several points to be improved are discussed based on the results.
Temperature and loading pressure are significant factors in producing a Biocoke. However, the effects of temperature and loading pressure on the production are inconsistent with increasing sizes of Biocoke. The quality, therefore, inside a large-sized Biocoke of 100mm in diameter is heterogeneous and the mechanisms regarding this heterogeneity and the methods to improve homogeneity are not clear. In this study, the mechanisms of heterogeneity were examined through evaluation of the quality inside large and small?sized Biocokes using X-ray CT imaging and image analysis. Results have clarified that the quality distribution inside the Biocoke can be estimated by most frequent value in a CT value distribution within 5mm width each in a radial cross-sectional direction. Also, the pressure and density distribution inside the large specimens could be estimated by the CT value and density of small specimens produced at different pressures. Consequently, based on the estimated pressure distribution resulting from the homogenization inside a Biocoke, different shapes of loading plates were developed. However, these loading plates were not effective enough to produce a homogenous large-sized Biocoke.
In this study, the structures and the NO formation processes of the “oxy-fuel” flames were investigated with a fully optically accessible tubular flame burner made by fused quartz. Using the optically accessible burner and non-intrusive laser measurement technique such as LIF and Raman spectroscopy, spatial as well as spectral distributions of the radical and stable species in the oxy-fuel flames were successfully obtained. As a result of NH-LIF measurement, it was found that the NH radical peak value is hardly affected by the unburned gas temperature. This NH behavior may attribute to the fact that preheating the unburned gas mixture has small effects on the NO emission of oxy-fuel flames. And furthermore, CO concentration profiles were qualitatively obtained which is hardly reported on the oxy-fuel flames. The obtained results in this study will play critical role in the research field of the oxy-fuel combustion to clarify its structure and construct the chemical reaction models.
From the engineering point of view, an image diagnose of burner-tip temperature is highly demanded to avoid thermal damage during operation. This study proposes an estimation method of burner-tip temperature based on shape evaluation of non-premixed microflame. An energy balance model involving the heat transfer through side and top of the burner is considered to derive a simple formula to estimate the burner-tip temperature from the flame shape. The methane microflame is experimentally observed under various conditions of ambient air temperature and fuel velocity. Obtained images are quantified by image analysis and three kinds of parameters which characterize the flame shape are successfully determined; the effective radius, the flame height and the quenching distance. The burner-tip temperature is then estimated by the proposed formula under each experimental condition. The estimated burner-tip temperatures show fairly good agreement the measured temperatures by thermocouple. This result suggests that the proposed method based on observation of the microflame allows reasonable estimation of the burner-tip temperature.
In filtration combustion, an exothermic reaction wave propagates in a porous medium through which there is gas filtration. Filtration combustion of carbon, for example, is used in various industrial processes such as underground coal gasification, in situ combustion for residual oil recovery, roasting and sintering of ores, blast furnace, and direct reduction of iron from beneficiated iron ores. A previous stability analysis found that there is a cellular solution to the Saffman-Taylor formulation, where mass diffusion is destabilizing. Insights into stability conditions are important for designing industrial processes, and numerical simulations are often conducted. The numerical models generally rely on certain assumptions, and their validity must be tested before using them. However, the 3-D nature of filtration combustion makes comparison between experimental data and numerical predictions difficult; detailed experimental observation requires sensing inside a porous medium, while 3-D numerical simulations are computationally expensive. This paper considers smoldering combustion of a thin paper in a narrow channel, which has been studied in the context of fire safety, and the governing equations are similar to filtration combustion. Since the phenomenon is essentially 2-D, comparison between experimental observations and numerical predictions is straightforward, enabling a simple check of the model assumptions.
Acoustoelasticity is a non-destructive method not only to detect flaw in material but also to estimate quantitatively the change of microstructure. The method has been often applied to the field of metallic materials, but it has been less done in the field of ceramic materials. So, firstly, the third order elastic constants of various ceramic materials, which could express nonlinearity in elastic deformation, were determined by measuring their ultrasonic velocities under uniaxially applied stress. Next, the relationship between those elastic constants and microstructure in each material was discussed. Thirdly, both the dependency of crack length and phase transformation on the third order elastic constants were examined using glass ceramics with indented crack and partially stabilized zirconia with anneal treatment, respectively. As a result, there was a significant correlation between the material nonlinearity and the complication of microstructure, and the estimation of ceramics microstructure using acoustoelasticity seems to be quite possible.
In the research, measuring method of impact load and impact load-deflection curve of a target specimen when a small impactor collided was proposed by using multiple coils on the basis of Faraday’s law of electromagnetic induction. The electromotive forces generated in the multiple coils with gradual increasing turns at different positions near the specimen when the impactor with an embedded magnet passed through the coils were summed to increase intensity of the electromotive force and extend measureable distance. The relation between the impactor velocity and the summed electromotive force was used as reference data to calculate the displacement, velocity and acceleration of the impactor. Furthermore, the impact load was also calculated from the acceleration and mass of the impactor. The penetration tests of a rubber plate were conducted by using the impactors with different tip shapes and three coils. Penetration or rebound of the impactor were identified from history of the impactor velocity. Measuring impact loads and impact load-deflection curves of the rubber plate were available through the use of the method even though the impactors were small.
The present paper deals with an experimental study of reflection and transmission of longitudinal elastic stress pulses at a discontinuity of two dissimilar cylindrical bars. Longitudinal wave propagation experiments in bars made of two dissimilar materials and different diameters were conducted using a split Hopkinson pressure bar set-up. The effects of cross section and impedance ratios on both stress and energy reflection and transmission coefficients were examined over a limited range of both ratios. The experimental results for the stress and energy reflection and transmission coefficients were in excellent agreement with the theoretical ones from one-dimensional elastic wave theory. The limitations of the one-dimensional elastic wave theory were discussed in terms of wave dispersion.
It is known that DBD (Dielectric Barrier Discharge) plasma actuator is a promising technology on active control of the flow separation. Installing the actuator in transportation equipment aids energy saving running. The purpose of this study is revealed that the shape of plasma actuator and the installation site for optimizing aerodynamic characteristics by using a CFD (Computational Fluid Dynamics) analysis and a wind tunnel experiment.
Double exposure holography and Fizeau-type interferometry are simultaneously applied to measure the stress field in the vicinity of fast propagating cracks in PMMA plate specimens whose thickness is slightly non-uniform. The sensitivity of double exposure holography is about a quarter as high as that of Fizeau-type interferometry, however, it can measure only the change in specimen thickness caused by the stress concentration near the crack tip without distortion of interference fringes by the non-uniformity of specimen thickness. Measurement results say that the derivatives of fringe order with respect to the distance from the crack tip are proportional to the -3/2th power of the distance from the crack tip, which is in agreement with the theory of singular stress field of plane stress. The stress intensity factors are also obtained from the interference fringes. It is shown that double exposure holography can obtain true value of stress intensity factor even in the condition that Fizeau-type interferometry cannot give the true value being affected by the non-uniformity of specimen thickness.