Thermoacoustic engines are one of promising devices for utilization of unused thermal energy. The object of this paper is to study effects of structure of regenerator in a thermoacoustic engine. Experiments were performed in a loop-tube-type traveling-wave thermoacoustic engine with branch resonator. The multi-mesh regenerator was constructed by combining of the stacked mesh having small flow channel to achieve lower onset temperature to require to induce self-excited gas oscillation and the stacked mesh having wide flow channel to induce larger pressure amplitude. The performance of the multi-mesh regenerator was clarified in relation to the length ratio of two types of the stacks.

This paper proposes a thermal energy harvester of MHD system using a temperature sensitive magnetic fluid (TSMF) which is magnetized by the temperature changes. Heat transport systems using TSMF have already been proposed by several studies, but both heat transport system and thermal energy harvester of MHD system have not been yet developed. The device is a 244 mm length rectangular closed channel of 4 × 5 mm. The operation of this device is carried out by two permanent magnets between the cooling and heating sections. The maximum voltage was about 0.055 mV in this experiment. It was about 80 % of the voltage obtained theoretically. Furthermore, parameters of the thermal characteristics were calculated.

The purpose of this study is to develop a new process for making silicon plate of less than 100 μm. Silicon plate of less than 100μm will become flexible and be utilized for flexible solar panels. Although experiments with high-temperature molten silicon were difficult to do in our laboratory, we performed model experiments with low melting point metal. In the experiment, we attempted to solidify a metal plate less than 100 μm utilizing surface tension of the molten metal. Moreover, we attempted to apply gas flow, as external force, to the molten part before solidification to make the plate thinner. As a result, metal plate became thinner than previous experiment. However, the plate width became narrower. We need to investigate the cause of becoming narrow of the metal plate width.

In this study, the coating process of TiN film on quartz substrate by thermal chemical vapor deposition has been conducted experimentally. Raw material of TiCl₄ vapor was premixed with excessive nitrogen and hydrogen gases through the glass beads packed bed. The length, inner diameter and porosity of the packed were 2 m, 0.7 mm and 0.609 respectively. There were two regions for the growth rate distribution of TiN film along the axis in the tubular reactor. In the first region, the growth rate increased with temperature at the inner wall. On the other hand, in the second region, the growth rate was found to decrease exponentially with axial position in the reactor and could be controlled by the diffusion rate of TiCl₄. Furthermore, two dimensional numerical simulation of heat and mass transfer during thermal CVD has been also conducted.

This study focuses on the concentration dependency of ethanol diffusion phenomenon. It is assumed that the flavor variation of whiskey related the variation of the molecular movement. In many cases of measuring the mass diffusion phenomena, it is assumed that mass diffusion coefficient is constant. However, in the case of the solution there is a concentration-dependent on diffusion coefficient such as an aqueous alcohol solution, measurement of a low concentration difference has been carried out. There is a need for measurement of a high concentration difference for simulating the movement phenomena of alcohol solution. In this study, transient diffusion field of ethanol aqueous solution system was visualized by an optical interferometer. In the results, it could be observed that the concentration dependence of the diffusion coefficient in the high concentration difference.

Several years ago, it was reported that the magnesium tin oxide nano particles exhibited cell characteristics. This interesting phenomenon was induced by UV irradiation and showed photochromic behavior. Recently we synthesized zinc silicon nanoparticles, which also showed photochromism like previously mentioned nano particles. In this study, we focused on structure of zinc silicon nano particles and proposed its photochromic principles. Furthermore, we examined zinc silicon particles also exhibited cell characteristics or not.

In this study, a rational study on the energy consumption of pre-drying process of the polymer pellets was carried out. Polyamide with pellet shape was used as the test material, and the weight change at different drying temperature was measured by a moisture analyzer. The diffusion coefficient of moisture considering the effect of temperature and moisture fraction within a pellet was derived from the obtained results, and a model for the simulation of drying process was built. Electric energy consumption for the drying process that was predicted by this model showed that there was an appropriate drying temperature that minimizes the energy consumption to achieve a prescribed drying condition.

Measurements of the thermal conductivity and specific heat of nanofluid of carbon black were performed at room temperature. The transient hot-wire method using parylene-coated Pt wires was employed for measurement of thermal conductivity. The thermal insulation method was employed for measurement of specific heat. The present paper shows these properties of base fluid (aqueous solution of 2.5 w% polyvinylpyrrolidone) and carbon black nanofluid (nanoparticle concentration of 5.0 w%). As a result of experiment, thermal conductivity of the nanofluid is higher than that of the base fluid because it is expected that thermal conductivity of carbon black is higher than that of water. However specific heat of the carbon black nanofluid is lower because it is expected that specific heat of carbon black is lower than that of water.

The dependence of volatile content of pulverized coal on its pyrolytic conversion has been investigated to understand heat and mass transfer. For coal with having about 40 % (coal A) volatile the char yield decreased dramatically with temperature until 823 K and approached slowly to the constant value. On the other hand, the decrement of char yield with temperature for coal with having about 30 % volatile (coal B) was smaller than that for coal A. The temperature increased slowly with time during gas generating and was equal or higher than 373 K for coal A. So, generated gas could include not only moisture but also part of released volatile. On the other hand, the generated gas volume for coal B was smaller than that for coal A. The coal A was more thermal decomposable material than coal B. The time course of generated gas volume and temperature during pyrolysis at T_R = 1023 K was different from that at T_R = 623 K because the coal B could decompose to the lighter tar than that for the coal A.

This paper describes a research on the effect of chevron nozzles on turbo jet engine performance and jet noise. Although chevron nozzles reduce the jet noise by an effect of the mixing between high velocity jet and external flow, they tend to provide a thrust loss at the same time. In this research, the experiment has been conducted for several kinds of chevron nozzles installed on a small turbo jet engine, in order to evaluate both aspects of noise reduction and thrust loss. Four kinds of chevron shapes and two kinds of nozzle exit geometries have been used in the experiment and the obtained results have been compared with that of the reference nozzle.

The response characteristics of a stretched cylindrical diffusion flame to oscillation of air flow was investigated experimentally. The cylindrical flame used in this study has a convex curvature with respect to air stream. The fuel used was methane, diluted with nitrogen, and the oxidizer is air. Oscillation frequency f was varied from 5 Hz to 250 Hz. Velocity at the outlet of air supplying nozzle was changed sinusoidally with four speakers. To evaluate a velocity gradient in oxidizer side from the flame front, the air velocity was measured using PIV. Flame radius, flame thickness and flame luminosity were obtained by high speed video camera. Results are summarized as follows: Fluctuation amplitude of the flame radius changes quasi-steadily in a low frequency range (5 Hz~25 Hz). The fluctuation amplitude decreases with increasing f when f is larger than 25 Hz. However, the response of flame luminosity is not quasi-steady at the low frequency range. Fluctuation amplitude of the flame luminosity has maximum value with respect to f, the maximum value is larger than that of a steady flame. The behavior of flame luminosity is different from that of flame radius.

Highly efficient cooling of combustor liner-wall is essential for high thermal efficiency as it requires high turbine inlet temperature, and film cooling is adopted there. In some cases, liner-wall has wavy shape to simultaneously attain high strength and light weight. In this study, film cooling effectiveness and heat transfer coefficient were measured from one run of experiment using two different thermal-conductivity materials as liner-wall by steady-state infrared thermography method. Two series of wavy liner-wall optimization were performed by using an orthogonal table in the design of experiments. The present results showed the wall-shape optimized for more geometric parameters with shorter wave length had higher film cooling performance in most of the cooling flow-rate range.

The characteristics of heating particles by methane clustered microflames and the structure of those microflames were experimentally investigated for the application of flame synthesis. The burner consisted of six fuel nozzles arranged in a hexagonal configuration at a distance of 2.5 mm from an additional center nozzle through which air and TaN particles were supplied. It was found that the fuel and air flowrates changed the state of flame merger, which was categorized into 4 states. An air jet from the center nozzle was found to be preheated by surrounding microflames and to establish preheated air diffusion flame inside the clustered microflames, which results in heating particles up to ultra high temperature.

Aluminum is expected to be one of candidates to store energies that has generated by renewable source such as solar and wind powers, which yields a sustainable energy cycle between aluminum and alumina. In the present paper, we developed an aluminum powder burner to extract heat and emission by the combustion for power generation. We supplied 3 micron aluminum powder with air to the cylindrical combustor with a backward step and achieved continuous combustion after ignition. We then investigated the flammable map and it was found that the limiting equivalence ratio for blow-off increased with the total air flow rate.

As means for a stable premixed combustion, there is a so-called cyclone combustor, which consists of a cylindrical chamber and fuel nozzles installed tangentially on the side wall. In this combustor an extremely stable flame can be obtained in the swirl flow, formed along the inner wall of the combustor. In general, it is difficult for the clean combustion to occur in biomass combustion. In the present study, experiments on the biomass combustion by the cyclone combustor were carried out, and comparing fuel gas jet flames. Wood charcoal, bamboo charcoal and white-pellet were used for biomass fuels. The effect of the fuel on the NOx formation and flame temperature were examined. It was shown that the temperature profile and NOx formation of the biomass flames are almost the same as those of the gas flames.

The demand to avoid volatile solutes has increased from the environmental point of view. However, most of polymer materials have hydrophobic surfaces, which make it difficult to use hydrophilic paints or glues. Hence, the surface modification with titania particles is expected to be one of convenient methods. In the present study, we developed a turbulent premixed burner, in which tetra-2-ethyl hexoside（TA-30）diluted with isopropyl alcohol （C₃H₈O）was sprayed. We applied the burner to polyethylene plates, painted hydrophilic pigment and investigated the adhesive force in several conditions to find the optimal condition.

The purpose of this study is to improve the spray characteristics of the nozzle, which was developed in the previous study, for direct injection Diesel engins. The nozzle obtained excellent spray characteristics only by changing geometric shapes of the nozzle holes. In this study, the effects of geometric shapes of the nozzle holes on spray characteristics were examined. As a result, they were improved distinctively when the round inret shapes of the nozzle holes were settled, breakup length been short about 20 %, and spray angle been large about 50 %, compared with sharp shapes of the nozzle holes.

Polycyclic aromatic hydrocarbons (PAHs) generated in combustors are itself exhibit carcinogenicity and believed to be precursors of the particulate matter. In this study, measurements of PAHs were carried out for Counter Diffusion flames of iso-Octane and propane fuels by using the Thermal Desorption - Gas Chromatography/Mass Spectrometry system. Experimental results were compared with numerical results calculated by using the KAUST 1 mechanism. As a results, experimental results demonstrated that cyclization rate of PAH is too fast. Numerical results are compared with experimental results and room for improvements has been shown.

Biogas-air coaxial jet flames are actively controlled through manipulation of the vortical structures and the associated mixing with miniature actuators installed on the annular nozzle. CH₄ is diluted by N₂ or CO₂ to mimic biogas, and the emission characteristics and the temperature fields for the controlled flames are examined under different dilution rates. At low dilution rate, it is found that CO emission is significantly reduced due to the homogeneous mixing by the large vortices, which leads to premixed-like combustion. On the other hand, at high dilution rate, stable combustion can be achieved through the stratified mixing by the small vortices.

Fundamental combustion characteristics of lifted flames at high-temperature oxygen combustion conditions were investigated experimentally and numerically. Two types of the flame structures for lifted flames were identified by experimental flame images captured by a still camera with a CH band-pass filter as well as computations. One could be classified to be a tribrachial lifted flame, and the other could be classified to be mild combustion. In 2-D computations, the reaction zone was formed beyond the stoichiometric line at mild combustion conditions.

The stability limits and emission characteristics of ammonia-air diffusion flames stabilized by swirl were investigated using a 50 kW micro gas turbine burner. Two liners were used, a cylindrical glass liner and a tapered gas turbine (GT) model liner. The flames were stabilized at equivalence ratios of 0.7 to 1.4 at inlet gas temperature of 298 K. The GT model liner resulted to a slightly wider stability range and lower unburnt ammonia emission. For both liners, ammonia emission increased while NOx emission decreased with equivalence ratio. The sum of NOx and ammonia emissions were found to be minimal at stoichiometric condition.

We have developed a heat flux sensing method with MEMS technology on an inner wall of an engine to measure the heat loss. In the case of measuring heat fluxes in the engine, sensors are required the durability, the shape which does not disturb combustion fields, the property similar to the material of the engine wall. Therefore we produced heat flux sensors with an aluminum alloy (AC8A) which is used to the engine material. Then we conducted a heat flux measurement test in a laminar flow combustion field and the RCEM with this sensor. As a result, the sensor could measure 15 MW/m² level heat flux in engine environment.

The heat transfer mechanism on a combustion chamber wall of an engine has been investigated by measuring wall heat fluxes with an original MEMS heat flux sensor. The heat flux measurement test in a rapid compression and expansion machine was conducted under non-combustion conditions, and the sensor could capture the heat flux reflecting the effect of piston movement and a working gas flow. The measured heat flux was compared with that derived from a heat conduction model including a gas strain effect. As a result, there was a difference in the peak positions, but the peak values were approximately equivalent.

Hydrogen atom concentration in CH4/air premixed flame in a narrow channel is measured using a newly-developed two-photon absorption LIF (H-TALIF) setup with improved THG efficiency at 205nm. Laser fluence smaller than 0.09 J/cm² is used for H-TALIF measurement free of the interference from photodissociation. Numerical simulations considering only the adsorption of hydrogen atom on the wall are also conducted. The initial sticking coefficient of the H atom is estimated as 0.1 for SUS321 and 0.01 for quartz by fitting simulated H atom distribution to the H-TALIF measurement result.

Three-dimensional direct numerical simulation of a hydrogen-air turbulent premixed flame with decaying homogenous isotropic turbulence is conducted to investigate turbulence-flame interactions in a constant volume vessel. The detailed kinetic mechanism including 12 reacting species and 27 elementary reactions is used for the hydrogen-air reaction. Turbulence-flame interactions modeling is studied using a conventional flamelet model for reaction rate closure. The result shows that turbulence-flame interaction mechanism does not change significantly under pressure rising conditions, suggesting that this model could be also used in a pressure-evolving combustion system without further modifications.

To investigate the characteristics of flame dynamics due to combustion oscillation, high-speed OH planar laser induced fluorescence (PLIF) measurements of methane-air turbulent premixed flame have been performed in a laboratory scale swirl combustor. The measurements are conducted under conditions where the total flow rate is 250 L/min, and the equivalence ratios are 0.70, 0.81, 0.90. Pressure fluctuation and CH chemiluminescence are simultaneously measured during the OH-PLIF. The dynamic mode decomposition (DMD) is applied to the series of OH-PLIF images. The mode corresponding to the dominant frequency of the pressure fluctuation is found to be stripe shaped in the upstream, while it shows a relatively large structure.

Direct numerical simulations (DNS) of ignition of an ultra-lean n-heptane/air mixture with high EGR at high pressure have been performed using a reduced kinetic mechanism to investigate the effect of the strain rate of turbulence on ignition criterion and its mechanism. An initial high-temperature region is set for ignition at the center of the computational domain. From one-dimensional DNS results, it is suggested that ignition is supported by the cool flame. Two-dimensional DNS results show that the ignition delay time becomes longer in proportion to the square of strain rate averaged in the high temperature region in the induction period.

This study is performed to examine experimentally the effect of H₂ addition on the burning velocity of lean-propane premixed meso-scale spherical laminar flames in the range of flame radius rf approximately from 1 to 5mm. The mixtures having the same laminar burning velocity (S_L0=25cm/s) with different equivalence ratios (ϕ=0.5 and 0.8) and hydrogen additional rates (δ_H=0.0~1.0) are prepared. The rf and the burning velocity S_Ll of meso-scale flames are obtained by using sequential schlieren images recorded under appropriate ignition conditions. It was found that S_Ll at the same rf tends to increase with δH, where the Lewis number of the mixtures decrease as H₂ is added to mixtures.

A subgrid scale combustion model for large eddy simulation (LES) of turbulent premixed combustion is developed. The model describes the flame surface area based on fractal characteristics of flame surfaces, and the inner cutoff is predicted by a correlating function with the Kolmogorov length scale. An expression is introduced to accurately estimate the Kolmogorov length scale. A priori and a posteriori tests with direct numerical simulation data of a turbulent jet premixed flame reveal that the present model accurately predicts the Kolmogorov length scale and the flame surface area and the LES using the model adequately predicts mean temperature distributions.

This experimental study was performed to investigate directly the local flame properties of turbulent propagating flames at the same weak turbulence condition for hydrogen added ultra-lean propane mixtures. A two-dimensional sequential laser tomography technique was applied to obtain the relationship between the flame shape and the flame displacement in a constant-volume vessel. The local flame displacement velocity S_F, curvature and stretch of turbulent flames was quantitatively measured as key parameters of local burning characteristics. It was found that the trends of the mean values of measured S_F ,S_F,m , with respect to hydrogen additional rates correspond well its turbulent burning velocity. The local burning velocity at the part of turbulent flames with positive stretch and curvature due to the Ma, S_Lt, attempted to be estimated quantitatively. As a result, a quantitative relationship between the estimated S_Lt and the S_F,mu at positive stretch and curvature of turbulent flames could be observed only for mixtures with Le>1.

To estimate the performance of ground heat exchangers in the case of shallow depth, we are developing a 2D numerical calculation program of the heat conduction. We have developed a 1D calculation program which is previous step of 2D calculation. The IDO scheme is employed in this program and this program can calculate with ununiformity mesh. The accuracy of the program with uniformity meshes are measured to be 4.5th-order. Furthermore, the accuracy of the program surpasses 4.5th-order in the case that ununiformity meshes are distributed with appropriate settings. We confirmed that temperature distributions have satisfactory accuracy, about calculations of estimating the performance of ground heat exchangers in the situation that a resolution of calculation is 0.1 [m].

This paper describes a common view platform of the Reference-Map for designing GSHP System with pile heat exchangers. This platform planning to be designed for GSHP designers, is able to be used when the boring data near the GSHP system installation area. Heat performance of a double-cylindrical ground heat exchanger at cooling and heating, is shown in the platform, according to parameters set by designers. 2-dimensional unsteady-state heat transfer in the under-ground is estimated due to numerical simulations, and calculated results are set to have the designing margin.

Ground Source Heat Pump (GSHP) is the temperature of the ground is stable throughout the year, COP is higher in cold climates compared to the air heat source heat pump that are affected by the temperature. However, GSHP takes a huge initial costs associated with the installation a number of boring work and heat exchanger. Heat cluster as a new method is able to pump heat from both the soil and groundwater to insert a well pile into the ground. In this method it is possible to greatly reduce the boring work and costs. Heat cluster system will perform heat exchange by actively pumping groundwater into the well pile by the purge pump. Its heat transfer mechanism is not clear. In this study, we tried the development of the underground heat transfer simulation model that contains soil and the flow of groundwater.

This paper describes thermal system dynamic analysis of a GSHP with pile heat exchangers. Ground source heat pump system is un-steady state system, so that heat demands in residences and heat transfer in the ground are depend on operation time and annual season. It is important to predict the system behavior with high performance, so the development of system dynamic analysis tool is needed. Numerical modeling of fan-coil units, heat-pumps, brine flow and ground heat exchangers is done.

The GSHP system can be cooling, heating and hot-water supply with the ground source heat energy, but it was expensive in general residence. A GSHP with pile heat exchangers (PHEs) is expected to reduce the initial cost compared with the conventional GSHP systems. However, the thermal performance of GSHP with PHEs and influence of ground temperature with GSHP with PHEs are unknown. This paper described what results and subjects of thermal evaluation of the GSHP (Ground Source Heat Pump) system with pile heat exchangers for the residence.

This paper describes thermal and installation evaluations of the double cylindrical pile heat exchangers that are used for ground source heat pump systems. Installation method of this ground heat exchanger is rotation pipe burying method, and it is possible to realize 0.6m/min and more high burying speed under soft ground condition with N value < 20. This heat exchanger has a structure of a double cylindrical heat exchanger, so it is easy to predict inner heat transfer. Due to numerical simulations, these heat exchangers is expected to be a same thermal performance as an ordinary boahole-type ground heat exchanger with same vertical length.

Heat demand in the general housing, so is shown next generation energy conservation standards, it is predicted maximum heat demand from the relationship between outside air temperature and the set room temperature. In heat output 5kW about and think from this point of view, air-conditioning correspondence is possible heat pump is considered appropriate. For 5kW class of heating and cooling for the brine heat pump, to report the results of testing the brine return assumed thermal performance when the temperature is mounted on the high shallow geothermal heat from the ground. The test results, energy consumption efficiency is 2.7 to 4.4 in the heating test, became the 2.4 to 5.7 in the cooling test.

Thermal performance evaluation of a pile heat exchanger utilizing shallow depth ground source heat was investigated numerically. The whole pile heat exchanger system including water natural convection was evaluated using CFD. The singularity of the water density around 4 degrees C is included as a phenomenon. Therefore the utilization of CFD is effective for development of a low-cost pile heat exchanger. Each phenomenon in the heat exchanger system was explained numerically.

Ground source heat has recently attracted considerable attention as renewable energy. The temperature of the underground at less than 100m depth is constant by geothermal energy throughout a year. Ground Source Heat Pump (GSHP) absorbs energy from the earth by applying this constant temperature. The coefficient of performance (COP) approached to 12.3 in cooling mode and 4.3 in heating mode. Totally, COP of GSHP with direct expansion method is higher than that in air-source type heat exchanger or indirect heat exchange method.

Thermal load tests of the ground-coupled heat pump (GCHP) system for heating and cooling are made for evaluating the system performance and the operation characteristics. The GCHP of the experimental apparatus has direct expansion ground heat exchangers. The refrigerant in the GCHP exchanges heat directly with the ground by evaporating/condensing in the ground heat exchangers. In the heating mode, the coefficient of performance is about 3.8 and the operation behaviors are usually stable. In the cooling mode, the outputs sometimes fluctuate up and down. The phase of the refrigerant changes in the ground heat exchangers. The behavior of the refrigerant needs to be analyzed for repressing the instability in the cooling mode operations.

A ground source heat pump that use direct expansion method uses an underground heat exchanger which is put a copper pipe directly in a borehole of 20-30 m. We have carried out an experiment using the underground heat exchanger which inserted the copper pipe in the steel pipe pile. In the present paper, we have described the thermal performance of the ground source heat pump when 15 steel pipe piles were used. The prospect that coefficient of performance of this method was higher than that of the indirect method of ground source heat pump was obtained.

Effective heat utilization systems such as ground water and sewage heat using the heat pump have been studied. During system operation, the following problem occurs, biological fouling, logarithmic growth and blockage of the heat exchanger. Therefore, we developed a shell and tube heat exchangers added with scraping type desludging equipment. In this paper, we confirmed blockage and deslugging effect of heat exchanger in use of sewage.

To investigate the influences of briquette size and density on flaming combustion of highly densified biomass briquette, combustion experiments were carried out with the cylindrical briquette made of cypress sawdust. In the flaming combustion duration, it is observed that the average mass loss rate ((dM/dt)_mean) of briquette per specific surface area (S/V, V: volume) is proportional to the surface area (S) of the briquette and is independent of the briquette density(ρ). In the range of this study, it is demonstrated by introducing Fourier number that the flaming combustion duration (t_f) is proportional to the product of the briquette density and the square of an inverse number of the specific surface area (t_f∝ρ(V/S)²).

This study is aiming to develop an effective and safe direct combustion method for woody wastes containing seawater by applying the two-stage combustion method for woody biomass. Combustion experiments are performed in a small combustor using simulated wastes with moisture contents of 13, 22, and 38 %, which are prepared by saturating woody chips with artificial seawater. No-salt-containing woody chips with moisture content of 17 % are also used for comparison. The experiments revealed that under the two-stage combustion method, the diffusion of salt could be suppressed in the low-temperature range of below 1030 K.

Heat and mass transfer during pyrolysis of measure components have been investigated experimentally and numerically. For Cellulose powder, when the convective heat transfer was taken into consideration, the calculation temperature had the second plateau at about 550 K due to the thermal decomposition and agreed qualitatively with the experimental ones. However, there was the remarkable difference between the experimental temperature and calculation one because of heat of reaction. The calculation result for gas flow rate agreed qualitatively with the experimental one until 3min except for evaporation of water. For Lignin and Xylan powders, the calculation maximum gas flow rate was lower than that of experimental one because the calculation temperature was lower than that of experimental temperature.

The heat and mass transfer characteristics during torrefaction of packed bed of bamboo powder have been investigated. In previous study, heating process was carried without carrier gas, resulting temperature distribution the temperature rise and final temperature varied depends on the locations inside the packed bed. Thus, it is difficult to evaluate the relationship between the chemical reaction and the temperature. By improving the reactor, allowing the heating process with carrier gas, the temperature rise became identical, resulting thermal decomposition in every locations occurred simultaneously, making the thermal reaction behavior became more obvious. The almost constant gas generation section after the peak was considered as the result of thermal decomposition of hemicellulose, which occurred in stages at temperature range 400 K < T < 600 K, as shown in the thermogravimetric result.

An experimental study was performed to investigate pyrolysis and gasification characteristics of large wood cylinders (ramin and Japanese cypress). First, wood samples were pyrolyzed under Ar atmosphere to produce chars using thermobalance. Then, the gasification rates were measured using an isothermal method at 1173 K under O₂/Ar atmosphere. X-ray computed tomography (CT) was used to observe intra-particle structure of wood samples at the macroscales. X-ray CT well visualized relatively large pores aligned along axial direction and found a difference in pore structures between ramin and Japanese cypress chars.

In order to utilize the unused biomass spread in broad area, a high efficient and compact biomass power plant is demanded. In this study, the design and control methods of the biomass downdraft gasifier for solid oxide fuel cells (SOFCs) were investigated. Using the calculation model of biomass gasifier, the experimental data and calculated data were compared. The validity of the model was confirmed, it was possible to predict the composition of the gasified gases with the parameters (Temperature, Supply of biomass, Air, Steam and Compositions of biomass). Furthermore, from the I-V characteristics of the SOFC fed by the gasified gases, it was confirmed that the power output by the gasified gas was about 0.85 times as large as that by pure hydrogen.

In the supercritical water gasification (SCWG) of shochu residue, equipment blockage by tar generated from feedstock is a technical problem. In order to confirm the validity of the tar formation inhibitory effect by addition of radical scavenger, SCWG experiments of shochu residue using the pilot plant were conducted. As a result, the validity of the tar formation inhibitory effect by addition of radical scavenger was confirmed from the pressure loss of equipment, carbon gas efficiency and overall heat transfer coefficient of the heat exchanger.

This paper describes the effect of feedstock heating rate on supercritical water gasification of glucose and guaiacol mixture. Glucose is a model compound for cellulose, and guaiacol is a model compound for lignin. A laboratory scale continuous reactor was used in this study. Mixture of glucose and guaiacol was fed to the reactor at 600 ^oC, 25 MPa through a pre-heater where the feedstock heating rate could be controlled. The concentrations of glucose and guaiacol were 0.36 and 0.14 wt%, respectively. Feedstock feeding rates were 1 and 2 g/min. Three lengths of preheaters, 0.45, 0.9, and 1.8 m, were employed. The longer the preheater is, the slower the heating rate for the same feedstock flow rate. Thus, effect of feedstock heating rate on gasification efficiency was studied. High heating rate was effective to improve the carbon gasification efficiency even for glucose-guaiacol mixture, but when heating rate gets close to 25 K/s, decrease in carbon gasification efficiency was observed. This may be due to the interaction between glucose and guaiacol similar to that observed for cellulose and lignin.