Light wall structures with high sound insulation performance are desired to be developed for houses and fuselage of vehicles. In this paper, a new light sound insulation structure is proposed. It is constructed with light inflated membrane bound by hard wire nets. By impedance tube tests, the proposed structures were proved to have not only high but also adjustable sound insulation performance by tuning the inside air pressure, which means stiffening the membranes. This structure can also construct a light sound insulation panel with high sound insulation performance by being inserted between light double walls.

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Local active noise control systems create a zone of quiet around a physical error sensor location. The zone of quiet is generally small, and as such, the physical error sensor is placed at the desired location of sound attenuation, which is usually inconvenient. Virtual sensing algorithms have been developed to aim for creating the zone of quiet at virtual sensor location that is remote from the physical error sensor. However the sound attenuation of the traditional virtual sensing algorithms worsen by change of primary source location that alter the transfer characteristics between a physical sensor and a virtual sensor. This paper presents a method to maintain the sound attenuation at a virtual location in change of sound incident direction of primary source and show positive results of experiments in an anechoic room. The proposed method estimate sound incident direction of primary source to use signals of two microphones and be able to switch between an appropriate filter that is measured in preliminarily identification stage to estimate signal at virtual sensor location.

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In this paper, in order to solve the characteristics of the radiated sound field generated by vibration of a flat elastic plate in a small enclosure with rigid wall we try to apply a numerical simulation technique using the finite difference time domain (FDTD) method to the coupled analysis of the vibroacoustic characteristics. The update equations for the FDTD simulation in the sound field and in the elastic body modeled by the isotropy material are coupled at the boundary of both the mediums. Numerical results show that frequency response changes depend on the opening shape and/or the volume of the enclosure. Since the experimental results using a vinyl chloride plate show the same tendency as the numerical results, the validity of the numerical simulation using the FDTD method in this paper is confirmed.

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Wire net often generates aerodynamic sound under some conditions in uniform flow. We simplified it by two parallel circular cylinders with cross cylinders. Separation of two parallel cylinders are four times the diameter . The effect of cross cylinders placed either at the upwind or downwind sides of two parallel cylinders are examined for various pitches(p_z/d_x=4～32) and angles of attack. With cross cylinders placed upwind, aerodynamics sound becomes intense in any pitch. But placed downwind, aerodynamics sound becomes weaker as the cross cylinder's pitch become narrower. Finally when separation of two parallel cylinders is equal to cross cylinder's pitch like a wire net. it doesn't generate noticeable sound. Measurements of the mean velocity field by LDV show that cross cylinders tend to elongate recirculation region of the upstream cylinder and to make the point of vortex roll up backward, leading to a weaker aerodynamic sound.

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Rolling noise is generated by the vibration of wheels and rails due to the excitation force, caused by roughness on the surfaces of the wheels and rails. Theoretical models, such as TWINS model, have been widely used to gain better understandings of rolling noise. In this paper, the model is applied to Japanese railways and validated in terms of vibration and noise. Through the validation work, it is shown that the predictions show a close correlation to the measurements. For the noise spectra, the contribution of the rail to rolling noise is found to depend on the type of tracks.

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It is necessary to understand the vibratory properties of a track and a wheel in order to evaluate the rolling noise. In this paper, focusing on the vibration of a wheel, we measured the accelerance of the corrugated wheel by the impact test. Then accelerometers were temporarily placed on the tire and web of the wheel of a vehicle which runs on a narrow gauge, we have measured the acceleration of the rolling wheel. In addition, we reported the vibratory properties of a wheel with a wheel flat and passing a turnout.

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This paper attempts to improve the performance of ear-plug type earphones. The transmission characteristics of the ear canal with/without earphones are different. Therefore, the sound quality of the earphone is a little poor compared with audio speaker. In addition, it is well-known that the acoustical characteristics of ear canal vary among individuals. Therefore, we are studying to predict the acoustical characteristics of ear canal with ear-plug type earphones by using transfer matrix method and are studying how to improve the transmission characteristics of the ear canal. In this paper, a method for adjusting the resonance characteristic of the ear canal with earphones to the characteristic of the ear canal of AV speakers without earphones using digital filtering technique is proposed. With this method, the improvement of the sound reproduction performance was verified on the basis of experiments.

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It is necessary to examine what kind of vibration and swinging is comfortable, in order to develop the comfortable human-machine interface using vibration or swinging. This study is focusing on the fluctuation in the period on the rhythm produced by the human; especially the stroke interval of the air stick is examined. The air stick is a simple version of the devil stick which is a kind of street performance. First, the portable measuring system of the stroke interval is developed by sticking two strain gauges on each hand stick and putting a wired battery driven strain amplifier and a portable data recorder in a knapsack which the performer wears. Then, the fluctuation is measured and the power spectrum is examined. As the result, it is clarified that the power spectrum shows the downward-sloping tendency in the low frequency range, and it shows the relation of about 1/f averagely.

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Experimental Statistical Energy Analysis (ESEA) is applied to analyze the vibration energy flow on violin body. The violin body is subdivided into six SEA subsystems. The analysis can identify the power flow through the subsystems and the power input into each subsystem under the impact excitation at the bridge which connects the strings and the body. The analysis results for two kinds of violin are compared. It is shown that three pieces of knowledge regarding better violin are obtained as the followings, 1) damping of the body structure is small, 2) the frequency distribution of power input into the body is in inverse proportion to square root of frequency and 3) the vibration energy on the back plate is propagating only from the top plate through the sound post. The fundamental discussions on the knowledge 2) and 3) are also carried out.

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Vibration and noise need to be calculated with a high degree of accuracy to estimate the radiated noise and vibration induced by the electromagnetic force from a motor. In the case of inverter motors, changes in rotation speed and load lead to changes in exciting frequencies and amplitudes of electromagnetic force harmonics. We developed a way to analyze frequency responses of electromagnetically induced vibration using the electromagnetic force in a representative revolution speed in the above conditions. We measured and calculated a sample motor's vibration induced by electromagnetic force of time order harmonics, which has a dominant effect on the overall vibration, and we compared levels of vibration velocity. We calculated both rotation speeds and vibration velocity levels, which had three observable peaks with a high degree of accuracy.

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The isobaric heat capacities of liquid ethanol are measured. Our group constructed a flow-calorimeter in 1996 for measuring specific heat-capacity at constant pressure of liquid refrigerants. The improvement of apparatus is continuously conducted. In 2008, Suzuki reconstructed the apparatus of a flow calorimetry and a stable mass flow rate became possible by introducing plastic accumulators. And isobaric heat capacities of ethanol are measured. The measurements were obtained at 8 points in the temperature range from 280 to 320 K and along a pressure of 500 kPa. The expanded uncertainty(coverage factor of k = 2) for heat capacity is estimated to be from 0.57 % to 0.91 % . We confirmed that the apparatus is able to measure without influence of heat loss and to get the repeatability within the uncertainty. For more careful consideration, we measured for two different samples of ethanol supplied from different manufacturers under the same conditions. Measured values for the different samples agree within the uncertainty each other. The measurements don't perfectly agree with existing measurements reported by other researchers or derived specific-heat-capacity values from existing equation of state developed by Dillon and Penoncello within the uncertainty. Very careful assessment is requested for the isobaric heat capacity values of liquid ethanol.

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A near-IR laser based spectrometer for continuous measurement of stable carbon isotopes in CO₂ has been developed. ¹²CO₂ and ¹³CO₂ are detected with wavelength modulation spectroscopy and a Herriott-type multi-pass cell with a optical path length of 29.9 m using a distributed feedback laser diode in the 2-μm wavelength region. To measure the isotope ratio precisely, the influence of pressure and temperature variation in δ¹³C was evaluated. The limit of detection for ¹²CO₂ in our system was 16 ± 1 ppbv. The precision in the determination of δ¹³C was 0.1‰ for 120 seconds signal integration time at ambient concentration levels. We demonstrate that our system enables automated continuous measurements of δ¹³C of CO₂ in ambient air without any complex operation by users.

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JFE Engineering Corp. has provided ten facilities of high temperature gasifying and direct melting plant in Japan. These plants are able to treat various kinds of waste, such as municipal solid waste(MSW), industrial waste, ash, refuse derived fuel(RDF), asbestos, etc. Recently, a social demand of reducing the coke consumption is becoming larger. In this situation, JFE Engineering Corp. has studied various methods of reducing the coke consumption. In this paper, we show test results of application of Bio-coke as an alternative energy resource. However Bio-coke contains more than 70wt% of volatile matter, coke can be substituted by Bio-coke having some calorific value. In this study, the cut-down ratio exceeded 50%. This shows possibility of remarkable decrease in CO₂ emission.

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JFE Engineering has developed the advanced stoker-type incineration system “JFE Hyper 21 Stoker System”. It is equipped with some new technologies to meet requirement to a municipal solid waste incineration system. Main technology of this system is High-temperature Air Combustion Technology (HiCOT), which realizes low excess air combustion. This paper describes the numerical simulation of combustion behavior in JFE Hyper 21 Stoker System. Firstly, a few kinds of kinetic mechanisms of combustion reaction were examined to select suitable one for a large-scaled numerical simulation of HiCOT. After we selected Yetter mechanism, two kinds of three-dimensional models, HiCOT zone model and entire incinerator model, were made and numerical simulation was performed by using these models. In this paper, we show the effectivity of these models that clarify the combustion behavior in JFE Hyper 21 Stoker System using HiCOT.

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This report shows the results of LCA (Life Cycle Assessment) of the advanced stoker-type incineration system and sewage gas generation system. Both of them show the reduction of ELP (Environmental Load Point) and CO₂ emissions calculated by LCA. The case study is done to realize the effect of the establishment of the incineration plant attached to the sewage plant. By exchanging heat and fuel the attached system shows the good effect of CO₂ reduction compared with the non-attached case. Then the effectiveness of the cooperation of the some plants for constructing high-quality waste management system is shown.

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Recently, highly effective power generation in waste incineration is required from needs of the CO₂ emission control. On the other hand, severe self-imposed restraint values of their exhaust gas are adopted in various municipalities for regional environmental preservation. So, in many cases, the catalyst de-nitration tower with which the steam heating is needed on the downstream of the exhaust gas dust collector is set up. This study has aimed to satisfy both of the CO2 exhaust control needs and regional environmental preservation with meeting the self-imposed restraint value only by the S.N.C.R (Selective non-catalytic reduction for NOx emission control) omitting the catalyst de-nitration tower. We report on the S.N.C.R test in the numerical simulation related to the de nitration reaction and in the real furnace.

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The effect of a plasma feedstock gas on the composition of combustion products in plasma-assisted combustion was investigated by a spectroscopic measurement of an ethylene (C₂H₄) flame ignited and held by a plasma jet (PJ). Spectra of CH, CN and C₂ were detected in emissions from the flame ignited by N₂ PJ. On the other hand, only CH spectrum was detected in emission of the flame ignited by O₂ PJ. A decrease in the CN emission downstream was much faster than those in CH and C₂ emissions. In the case of N₂ PJ, an increase in the electric power to the PJ torch decreased the flame length.

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The authors realize a new prototype of plasma-assisted environmental protection aftertreatment system using atmospheric-pressure nonthermal plasma combine processes for super clean diesel engines. This system does not use any rare or precious metal catalysts and harmful ammonia or urea solution. A NOx aftertreatment system, using nonthermal plasma (NTP) reduction and exhaust gas components recirculation, is investigated. A pilot-scale system is applied to a stationary diesel engine using A type of heavy oil fuel. In this system, NOx is first removed by adsorption, and subsequently, the adsorbent is regenerated by thermal desorption. The desorbed high-concentration NOx is reduced by using nitrogen NTP with low flow rate. Moreover, NOx re-circulated into the engine intake reduces NOx emission. In the present experiments, a very high system energy efficiency of 385 g (NO₂)/kWh is achieved in the NOx reduction test. The developed system demonstrates excellent energy efficiencies to meet the most recent international regulation of marine diesel engine exhaust gas.

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Fundamental characteristics of N₂O decomposition by atmospheric non-equilibrium plasma were investigated to reduce greenhouse effects. N₂O/O₂/Ar system and N₂O/O₂/N₂ system were prepared to understand quantitatively the effects of plasma conditions (applied voltages and its repetition rates), O₂ concentrations, and gas flow rate on N₂O decomposition. In N₂O/O₂/Ar system, an N₂O concentration of 40 ppm was completely decomposed by the plasma at O₂ = 0%, however N₂O decomposition was decreased with an increase in O₂ concentrations. Unfortunately, N₂O/O₂/N₂ system, N₂O was formed by excess N₂ and O₂. Formation and decomposition mechanisms of N₂O were experimentally discussed. It is likely that N₂ + O → N₂O is a dominant reaction under N₂O/O₂/N₂ system.

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A unique SNCR system using dissociated ammonia generated by an atmospheric plasma has been developed to remove NOx from combustors. However, the NOx removal mechanisms are not clear. In this paper, chemical compositions of dissociated ammonia at the plasma reactor exit were investigated. NH₃ decomposition, hydrogen conversion, and nitrogen conversion were measured at various applied voltages and flow rates of ammonia gas. In the NOx removal technique, a temperature window enlargement of 150 °C was attained at the lower boundary of the temperature window. It found that dominant species causing the temperature window enlargement was molecular hydrogen formed by disassociation reaction of ammonia in the plasma.

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This paper describes the development of ballast water treatment systems using interaction of bubbles, shock waves and discharges. In this development, we have cavitation flows during nozzle and diffuser part (reactor) and discharge in this cavitation area. The aim of this investigation is to satisfy the IMO standard for ballast water treatment by using our special cavitation discharge water treatment system, and to modify the geometry of reactor part in the circuit by using simple measurement method of the bubble density and diameter. In this paper, it is concluded that (1) the disintegration rate of plankton (more than 50 μm) by using cavitation discharge is satisfied in IMO standard (D-2), (2) by simple measurement method, the result of bubble density distribution in the reactor almost agrees with the position of electro node for discharge optimized with efficiency in the previous experiment.

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A process to recover base oil from waste lubricating oil is proposed in this study, which is based on solvent extraction with membrane. In this process, organic solvent is circulated in a closed loop, leading to a resource saving. Residue consists of only impurities in waste lubricating oil, such as suspended particles, aqueous droplets, soot and tar, leading to a waste reducing. This process includes a fractional distillation, too, but it is for separating out organic solvent from oils. Then, temperature for fractional distillation is lower than 100 °C, leading to an energy saving. Rubber film is utilized as membrane, whose polymer network structure works as filter to separate impurities from oil dissolved in solvent. In order to verify the feasibility of this process, effect of extraction period, solvent volume and extraction temperature on both yield and quality of the extracted oil was experimentally estimated.

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We researched concerning the new energy technology of producing the hydrogen gases with the organic refuse by using sunlight and phototropic bacteria. Electricity can be generated by supplying the produced hydrogen gases to the fuel cell. Hydrogen production efficiency enough to put it to practical use has not been obtained in the past though a full-scale experiment for the hydrogen production that uses algae and the microorganism that does the photosynthesis has been conducted. That is, the cost performance for practical use is not obtained. We did an experimental research that used the wavelength conversion material of sunlight and the optical reflection material of the aluminum foil as a method for the efficiency gain of the hydrogen production. As a result, the design parameter of the system to produce hydrogen with the waste fluid by using the purple non-sulfur bacteria that carried out photosynthesis was able to be decided. Substrate (The sugar manufacture waste fluid: [Molasses]) dosage in which the highest incidence of hydrogen was obtained was 0.4mg/100kcells^*day for the pure culture system. Moreover, the improvement of the hydrogen production efficiency of about 15% was obtained in the maximum with a light wave length conversion net. A design parameter of the biomass hydrogen energy production system and basic data concerning the efficiency gain of the system were able to be obtained from the above-mentioned results.

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An efficient configuration method of a biogas-fuelled cogeneration system (CGS) in a sewage treatment center was investigated. The efficient configuration was clarified by classifying a relationship between exhaust heat recovery efficiency (η_ehr) of a micro gas turbine CGS, and the ratio of average heat demand to biogas production of the facility (Q_h.d/Q_b.p). It was found that on the point of view of biogas energy recovery, reduction of unutilized biogas and electrical power demand efficiencies, the most efficient CGS was obtained under Q_h.d/Q_b.p = η_ehr condition. If a CGS with lower η_ehr such as a fuel cell is used under Q_h.d/Q_b.p < η_ehr condition, or a CGS with higher η_ehr such as a steam turbine is used under Q_h.d/Q_b.p > η_ehr condition, more efficient system can be obtained. On the other hand, suggestion for more efficient system when η_ehr cannot be conformed to the Q_h.d/Q_b.p value was also presented.

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The energy saving characteristic is investigated for a gas engine cogeneration system combined with a photovoltaic array and a gas engine heat pump with power generation or a gas-fired absorption chiller heater with input of exhaust heat, when it is installed into a hospital as an example of commercial buildings. The on-off status and load of each piece of equipment are determined to minimize the primary energy consumption of electricity and natural gas purchased from utility companies. This optimization problem is formulated as a mixed-integer linear programming one and is solved using a commercially available solver. A numerical study shows that the gas engine cogeneration system is superior to a conventional system in the energy saving characteristic: the energy saving rate of the system with the gas engine heat pump with power generation is about 11 %, and that of the system with the gas-fired absorption chiller heater with input of exhaust heat is about 8 %.

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Wind energy has potential and usefulness as natural energy, and can be harvested from wide range of windy area. We have developed a flexible piezoelectric device (FPED) composed of polyvinylidene fluoride (PVDF) and functional resin. The characteristics of the FPED are thin layer, light and flexible. Therefore, both a force caused by breeze and flow energy with various frequency spectrums can be harvested effectively using the FPED. In this study, we made clear electrical characteristics of the FPED and availability of an attached bluff body in uniform flow. Moreover, we validated electrical efficiency of the FPED which is laminated with a stretching resin and has a roughness surface such as woolen and small hemisphere.

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To decrease the power consumption of air-conditioning in the data centers, a packaged air-conditioner that contained the pump cycle was developed. The new air-conditioner has improved COP when outdoor temperature is especially low. In this report, the performance at the pump cycle was evaluated with a real machine of the test site. As a result of the verification, the stability of driving at the pump cycle was confirmed. In addition, it was shown the relation between outdoor temperature and total COP, and high driving efficiency at the low outdoor temperature.

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The aim of our study is to propose manufacturers and users should be building a sustainable society through quantification of the design for environment, DfE. For a background problem of global warming and depletion of natural resources, it is required to reduce the environmental loads of the products and services life cycle. In recent years, the way of using products and services have been changed according to the development of ICT. For example, we can buy products on the internet without going to the store. Since a smaller personal computer is carried around all the time, the environmental load assessment for not only “a product” but also “a product with others” and ”a product system” are needed. On this study, the environmental loads of “paper meeting” and “paperless meeting” using ICT as an example of product system are compared.

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The perforation of a thin liquid sheet by thermocapillary effect has been investigated. In a radial liquid sheet, which is produced by release of a liquid film spreading on a disk into the air, a laminar-turbulent transition occurs just outside the disk edge. The coherent turbulent structure after the transition forms the extremely thin liquid sheet locally and perforates it. In addition, the perforation is promoted by the impingement of a hot air flow on the thin liquid sheet. This perforation promotion requires specific condition of liquid flow velocity and airflow temperature. This study proposed the theoretical model of thermocapillary induced perforation of the thin liquid sheet and predicted the specific condition for the thermal perforation promotion in the radial liquid sheet. This model representing time diminishing sheet thickness is derived from a momentum balance between inertial force, Marangoni force and Laplace pressure. A simplified model gives the simple algebraic equation expressing the time required to the perforation. The validity of the theory is verified by comparing the theoretical perforation time with that calculated from a numerical simulation based on CIP method. The specific condition for the perforation promotion, which is estimated from the theoretical perforation time, agrees well with experimentally observed one. This agreement demonstrated that the perforation promotion is caused by thermocapillary effect.

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Formulations to predict mechanical losses of cylindrical flywheel rotor in small-scale flywheel energy storage system (FESS) were derived through computational analysis and experiment. Mechanical loss was defined as summation of windage loss and bearing loss. Approximation formulas of windage loss were obtained by parametric study via computational fluid dynamics (CFD) analysis. In addition, to validate the approximation formula, a fundamental experiment was conducted using a prototype FESS with the rotor radius of 0.225 m and rotation speed within 838rad/s(8000min^-1)under several internal pressure conditions. It was found that the mechanical loss predicted by the proposed formulas well agreed with that measured in the experiment.

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For understanding of film cooling flow fields on a gas turbine blade, this paper reports on a series of large-eddy simulations of an inclined round jet issuing into a crossflow. Simulations were performed at four blowing ratio conditions, BR=0.1, 0.5, 0.7 and 1.0 and Reynolds number, Re=15,300, based on crossflow velocity and film cooling hole diameter. Results showed that cooling jet flow structure drastically changed with blowing ratio. A pair of rear vortex and hairpin vortex were observed for BR=0.1. A periodic ejection of horseshoe vortex, a pair of hanging vortex, a pair of rear vortex and hairpin vortex were observed for BR=0.5. Similar vortical structures to BR=0.5 were observed for BR=0.7 although horseshoe vortex remained at a leading edge of the hole exit. For BR=1.0, in addition to the former mentioned vortices, spanwise rollers and vertical streaks were observed on an upstream edge of the jet. It was, consequently understood that the ubiquitous counter-rotating vortex pair which can be defined in the time-averaged flow field was actually originated in the different vortical structures with varying BR conditions.

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Extinction and flame structure of lean premixed and diffusion combined flames formed in a counter flow are investigated experimentally and numerically. The extinction limits can be divided into two regions. One is a diffusion flame dominant extinction region (DF-DE) in which equivalence ratio of LPF side (φ_L) at extinction limit is decreasing linearly with increasing fuel concentration of DF side (χ_U). The other is a lean premixed flame dominant extinction region (LPF-DE) in which effect of χ_U on extinction φ_L is increasing with increasing χ_U. In these two regions, the flame structures and its φ_L dependence are different greatly. In the DF-DE, the temperature has symmetrical profile regardless of φ_L and the temperature peak is located near DF. Since DF has higher temperature than LPF, LPF is thermally supported than DF. Temperature gradients between two reaction zones are decreasing with increasing φ_L, while laminar burning velocity (S_L) and burnt gas width (W_B) are constant regardless of φ_L. On the other hand, in the LPF-DE, the temperature has asymmetrical profile and the temperature peak leans to the LPF side. That is, the temperature gradient of LPF side is very steep compared with the DF side. Since LPF has higher temperature than DF, DF is thermally supported than LPF. Temperature gradients between two reaction zones are constant regardless of φ_L, while S_L and W_B are increasing with increasing φ_L.

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Objectives of this study are to suggest a new method to predict the stability limit of high temperature air combustion. For the first stage of this study, we investigated the effects of dilution by the burned gas on the ignition delay time. Dilution ratio is introduced to quantify the magnitude of dilution in high temperature air combustion with a parallel jet burner. The effects of dilution on the ignition delay time are evaluated by a chemical characteristic time with the dilution ratio. Flamelet equations are solved numerically to investigate the effects of dilution on the ignition delay time. Ignition time is defined as the time at which a temporal increase in maximum temperature becomes its maximum. The ignition delay time based on the maximum temperature includes durations of radical pool growth and of most reactive region movement. The ignition delay time based on the maximum value of Damköhler number corresponds to the duration of radical pool growth. With an increase in the dilution ratio, the ignition delay time based on the Damköhler number decreases, and then increases. This trend is attributed to the increase in temperature of mixture and the decrease in reactant concentration with the dilution ratio. The introduction of chemical characteristic time has generalized the ignition delay time.

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In this study, we measured PM concentration in diesel exhaust gas by laser-induced incandescence (LII). To evaluate the diesel particulate filter (DPF), the measurement was conducted at the point right after DPF exit. Four filters of different porosity and wall thickness were tested. In addition, EEPS system was used to examine the particle number concentration and calibrate LII signals. Based on the time-variation of PM concentration, an initial PM filtration efficiency and soot cake formation in DPF were discussed. The LII technique can be potentially applied to find the location of PM leakage through the filter and evaluate the after-treatment system.

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A polymer electrolyte membrane fuel cell (PEFC) with a porous-flow-field separator has been proposed as an alternative to cells with gas flow channels. In this study, basic characteristics of a PEFC with porous flow field were identified using a cell allowing local current density measurement and direct observation of the condensed water at the surface of porous material. It was shown that a stable operation can be maintained under conditions at high current density and low stoichiometric ratio of cathode air, but an operation with low relative humidity of reaction gases is difficult with the porous type separator. To clarify the detailed causes of these characteristics, the internal phenomena were investigated using a cell specially made for the cross-sectional observation of the separator or the temperature distribution measurement. The direct observations of the condensed water at the cross-section of porous flow field showed that the porous type cell is superior in drainage performance of the condensed water from the surface of gas diffusion layer (GDL), and the hydrophilic property of the porous material is important for better cell performance under high current density conditions. The measurements of temperature distribution on the anode GDL surface indicated that the increase in temperature near the reaction area tends to be larger in the porous type cell than in channel type due to the lower thermal conductivity of the porous media, and this resulted in the unstable operation with low relative humidity conditions.

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Effect of distribution of fuel gas velocity on performance of SOFC was investigated by experiments and numerical simulations. The fuel gas was supplied to anode-supported cells by two different methods: jet flow and parallel flow, and cell performance was measured at 1000°C as changing H₂ flow rate in each method. In the case of the jet flow, the fuel gas jetted out a blow port and impinged on the fuel electrode surface. On the other hand, in the case of the parallel flow, the fuel gas flowed parallel to the fuel electrode surface. As a result, it was found that the cell-voltage in the case of the parallel flow was greater than that of the jet flow in the higher current density region. And the cell-voltage increased with H₂ flow rate in each case. These differences between the cell-performances were caused by overpotentials related to phenomena in the lower frequency region. Furthermore, the results of the numerical simulation indicated that these differences between the cellperformances had a significant correlation with the electromotive force.

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