The double diffusive natural convection arises owing to the rate difference between thermal and solutal diffusions in a fluid containing temperature and concentration gradients. The double diffusive convection of ascending hot smoke was numerically studied at the Prandtl number Pr=0.71, the Rayleigh number Ra=10^9 or 10^<10>, the Lewis number Le=5 to 50, the area ratio of hot part against unit area S_i=0.032 or 0.77%, the buoyancy ratio N=0 to 1. The ascending thermal plume occurred due to the fast diffusion of heat from the heat source even at N=1, and then the dilute pollutant gas was included in the thermal plume. The thermal buoyancy became weak owing to the diffusion of heat with the rising of smoke, and then the smoke fluctuated owing to the balance between thermal and solutal buoyancies. When the Lewis number is large, the plume strongly fluctuated.

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Heat and fluid flow characteristics of film flow along vertical grooved channels are investigated as a simple model of plate-type absorber. The film flow is affected by establishing a grooved part on the flat plate. Namely, it is expected that a film thickness becomes thinner at the edge of the groove as the flow deflects into the groove, and consequently fluid mixing is enhanced. In this research, in order to clarify the characteristics between the film flow pattern, heat transfer and groove depth, we have performed numerical simulations by using Volume of Fluid (VOF) method. In addition, we have also performed experiments with flow visualizations and compared the result with one of numerical simulations.

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Heat and fluid flow characteristics of flow in a channel with periodically grooved parts are investigated as a simple model of plate-type heat exchanger. It is known that the flow in the grooved channel oscillates when the Reynolds number increases, and heat transfer is enhanced for the oscillatory flow. In this research, in order to clarify the characteristics between the oscillatory flow pattern and heat transfer in a three-dimensional flow regime, we have performed three-dimensional numerical simulations by using spectral element -Fourier spectral technique. In addition, we have also performed experiments of temperature measurement and compared the result with one of numerical simulations.

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Fluid flow and heat transfer of opposing mixed convective flows induced around upward-facing, inclined heated plates were investigated experimentally. The experiments were carried out for air and with the test plates of inclination angles 15 to 60°. The flow fields over inclined plates were visualized with smoke and the local heat transfer coefficients of the plate were measured with thermocouples. The visual results showed that a separation of the boundary layer flow occurs first at the trailing edge of the plate, and then, the point of separation shifts toward the leading edge with increasing the buoyancy. It is also found that the above flow separation affects seriously on the local heat transfer coefficients of the plate. Moreover, the separation points and also overall heat transfer coefficients of the plate can be predicted by the non-dimensional parameter (Gr_Lsinθ/Re_L^<2.5>).

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Pyrolysis of woody biomass attracts attention as one of the methods of using biomass energy effectively. The phenomenon governing the pyrolysis are both heat transfer and chemical reactions. Although about 30% of moisture other than organic ingredients, such as cellulose and lignin, is included in the woody biomass, change of heat and mass transfer by moisture evaporation is hardly considered. In order to investigate about the influence moisture content of the biomass affects pyrolysis process, experiments (temperature and gas flow rate measurement, gas analysis) were conducted by dry and wet biomass.

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Miniaturization of reformer for a micro fuel cell system requires low flow loss and high reactive density of hydrogen generation and the carbon monoxide removal. We propose the designing method of reformer by optimizing its porous reaction layer and multiple branching flow channels. The method is based on the constructal theory proposed by A.Bejan. The optimization of the full cell reformer for a lightweight type Laptop PC shows that flow loss of 645.8 [Pa] and outlet CO concentration of 10 [ppm] were achieved for the total area of the reformer 4.6135×10^<-3> [m^2]. In addition, we have compared several reforming reaction system assuming chemical equilibrium theory.

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Steam gasification of cellulose powder has been studied, using a sponge-like porous Ni catalyst. The reactor with the catalyst was heated through an electric heater. The powder was quickly put on the catalyst surface kept at 800℃. The influence of the Ni catalyst poisoned by steam and the steam/carbon ratio (S/C) on product gas yield was analyzed. The most striking result is that carbon yield of the product gasses was almost constant for more than S/C ratio of 2.5 while hydrogen and oxygen yields increase with S/C.

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Numerical analysis of a porous type membrane reactor system for gasoline steam reforming has been done. It was clarified that restraint of steam permeation was important for high reformer efficiency in addition to promoting permeation of product gases. For more improvement of the reformer efficiency, two effective controls were proposed. First one was the pressure control in the purge lines to control the permeation rates at each load. Second one was the recirculation control of non permeated gases in the feed lines to enhance the reaction rate. Using these controls, the reformer efficiency was estimated at 75%. Moreover both performance of catalyst and membrane should be improved for 80% reformer efficiency.

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Velocity field around droplet was discussed during single droplet combustion in DC electric field. Tracer particles were inserted into combustion and electric field and velocities of them were measured using PTV method. Toluene droplets were burned between plate electrodes and DC voltages are applied between them. Experimental results show the velocity of tracer particle is uniform without flame, on the other hand, it is not uniform with flame. This indicates the tracer particles are considered to be charged in this case. This result also indicates that flame deforms the electric field because it contains many ions. This information is important because the deformation will induce ionic wind around droplet.

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A uniform-spray-stream burner for microgravity experiments was newly developed. Partially-prevaporized sprays were continuously generated by the condensation method. Mean droplet diameter of spray streams was controlled by the degree of superheat of fuel vapor-air mixtures leaded into a cooling section. Diameter measurements of droplets in a spray stream have been done for various spray generation conditions. The mean droplet diameter was constant during a test and the droplet diameter distribution could be controlled to be narrow. Droplets were uniformly dispersed in a laminar spray stream.

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The effect of ambient balance gas on the flame-spread rate over a PMMA sheet was investigated experimentally under microgravity and normal-gravity conditions. N2, CO2, He and Ar were used as the balance gas in order to change the gas properties such as heat conductivity, heat capacity and absorption coefficient. The result shows that the impact of the difference of the ambient gas on the spread rate is different between normal gravity and microgravity conditions. In normal gravity, thermal conductivity and the heat capacity are the dominant factors, and the spread rates are He>N2=Ar>CO2 with high O2 level. On the other hand, in microgravity, the absorption coefficient and thermal diffusivity play great roles, and the spread rates with CO2 balance are much enhanced in a quiescent condition whereas that with He balance is suppressed.

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Flame spread over solid fuels in a microgravity environment is an important area of research due to its fire safety implications in spacecrafts. Of all different configurations, flame spread over thin fuels in an opposed-flow environment is the simplest and, therefore, received most attention during the past decade of research. However, the concurrent-flow configuration in which the flame is known to accelerate is more hazardous. In this paper we study the transition between the two regimes experimentally and computationally. Experimental data on flame spread rate for different oxidizer velocity, positive and negative, are obtained from experiments conducted in drop tower as well as airplane flying parabolic trajectories. An existing computational code for opposed-flow flame spread is modified to model concurrent-flow spread as a pseudo-steady phenomenon. Good agreement is obtained between the experimental and computational results.

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The microwave was irradiated at the combustion field and the influence on the flame height was considered. Stick PMMA was used as a solid fuel. The intensity of microwave was constant. The outer diameter of PMMA was changed. The flame height and the combustion mass were measured. The inverter-controlled magnetron microwave generator was used. PMMA was used as a dielectric substance of the coaxial line. As the results, the flame height and the combustion mass were increased when microwave was irradiated during PMMA combustion. It is effective in combustion promotion to irradiate microwave during PMMA combustion.

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The combustion of a liquid fuel is a phenomenon with a phase transition from the liquid to the gas. We are proposing to the phase transition is promoted by applying the microwave and assist combustion. The coaxial heating device that can irradiate the microwave directly to the liquid is made, and the temperature distribution when the microwave was irradiated to the liquid was examined. This time, the rise in heat at position at 2mm from center of fuel chamber by using six thermo couples is measured and the difference of the measurement result is examined.

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Microfluidic devices have been applied to many kinds of chemical and biochemical applications including mixin, sorting, enrichment, extraction, heating, and cell cultures. Miniaturization and integration of chemical operations have many specific advantages such as increased speed, efficiency, portability, and reduced consumption through the merits of scale, short diffusion distances and high interface surface-to-volume ratios. The interface does play dominant role on the micro-flow. The non-linear effects of the interfaces cause the non-linear fluid flows. In this paper, several non-linear flow characteristics of the micro-flow will be described, based on the author's experiments. The transient flow analysis is also important to understand the non-linear flow field. The trends of the micro- nano- flow field analysis will be discussed. There will be lots of research topics on non-linear micro- nano- flow.

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A simultaneous measurement technique for velocity and pH distributions was developed by using fluorescence and a confocal scanner. The present study examines the ability to combine micro-PIV using fluorescent particles and laser induced fluorescence (LIF) with Fluorescein sodium dye whose intensity is strongly dependent on pH. A prism inside a 3CCD camera separates particles' fluorescence from that of dye. Two buffer solutions with different pH values were introduced through a T-shaped microchannel. Velocity-vector maps were obtained by ensemble-averaging velocities of instantaneous images with the spatial resolution of 15μm×15μm. A two-dimensional distribution for the flow field with a pH gradient was detected from fluorescent intensities with the spatial resolution of 5μm×5μm.

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Rapid mixing is essential on the micromixer in microfluidic systems. Mixing in microchannel relies mainly on molecular diffusion due to the laminar flow at low Reynolds number. In this study, the sequential switching of electroosmosis flow is applied to the mixing in microchannel. By switching of the electroosmosis flow sequentially to the T-junction microchannel, the mixing stream is segregated by the two inlet streams on and off, then the mixing process can be accelerated and controlled by increasing the contact surface of two liquids. In this report, the velocity and concentration fields were measured simultaneously by Rhodamine B and tracer particles of 1.0μm diameter suspended in the water.

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A simple measurement technique of colloidal particles' zeta-potential by using micro-PIV was proposed. This technique is based on a measurement technique using a closed cell filled with colloidal solution. In order to calculate the zeta-potential, the obtained velocity by micro-PIV is transformed to particles' electrophoresis velocity with a modified Mori-Okamoto equation, which considered an influence of a wall in parallel to the micro-PIV measurement plane. This technique enables to measure the particles' zeta-potential when the measurement plane was placed at 50μm away from the wall. The obtained zeta-potential is compared with that by other techniques for its validation.

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In micro-channel flow with backward step, the effects of the flow and heat transfer with the mixture of multi-size particles are investigated experimentally for the control of the flow and heat transfer field. In the area of micro-size, it is not easy to control the heat transfer with increasing and decreasing locally by devices and external forces but it is possible to perform using non-direct phenomena with the mixture of multi-size fluorescent particles in the flow. Because of the velocity distribution, the tracking line of multi-size particles may be different from the drag effects of the each body size. Then, the velocity distribution would be changed more emphasized by big-sized particles and passing by mid-sized particles. It would be needed three kind of particle size at least to perform and detect the phenomena. From the results, several qualitative interesting effects were given with the continuous pictures and immature image analysis, and the quantitative results would be got and reported after the building and confirming the newer image processing methods.

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The performance of the groove-embedded rectangular duct is investigated in this paper in the meaning of enhancing the fluid mixing under very low Reynolds number conditions. Both numerical and experimental studies have been carried out to discuss the groove shape effect on the mixing characteristics and to evaluate the numerical scheme and experimental procedures. The results obtained by each approach agreed fairly well with each other in a qualitative manner. By applying the groove, a higher mixing rate was obtained in a shorter length compared to a rectangular duct even in the channels with high aspect ratio. A better mixing was achieved with the case of asymmetric pattern than the symmetric case. The difference of the groove width also changed the flow and mixing characteristics, however, the total performance eventually did not differ much.

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In three phase contact line region with gas dissolution, phenomena which is marangoni flow due to non-uniform distribution of ingredient concentration is now an important technical issue in cleansing and drying process technology of semiconductor manufacturing industries. In this report, we look to micro liquid film flow in meniscus of three phase contact line direction, clarified the velocity change with time. Then absolute value of the velocity is different from wettability of solid surface. And we show that marangoni flow is useful for elimination of 50nm particles which is adherent silicon wafer. In particular, the elimination effect is noticeable trend to hydrop hilic surface.

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The effect of ionic diffusion on electric double layer (EDL) in the vicinity of the wall was investigated in a T-shaped microchannel. A large-area evanescent wave illumination technique and fluorescence imaging were applied to the measurement of two-dimensional distribution of EDL at the silica glass-electrolyte interface using a negative ion fluorescent dye, Alexa fluor 546. Moreover, the bulk velocity distribution and the diffusion distribution of K^+ were investigated by a micro-PIV technique and numerical simulation. It was concluded from these results that the spatial and temporal structure of EDL is affected by the convection and diffusion of K^+.

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When cavitation bubbles collapse violently, local high-temperature high-pressure spots are generated, which can be used for various chemical reactions, i.e., sonochemistry. It is necessary to control a sound field in order to generate these spots efficiently. We report two experimental studies: Observation of multi bubbles dynamics in ultrasonic field using a stroboscope, light scattaring and light attenuation technique.

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A particle separation technique without complex mechanical structure has been developed in a sub-mili channel. This is of importance to various operations in microfluidic devices. Size separation was demonstrated by utilizing acoustic radiation and electrostatic forces which acted simultaneously on the particles perpendicular to the flow direction in the sub-mili channel. By acoustic radiation forces an inhomogeneous distribution of particles was formed. By applying electrostatic forces the particles were moved parallel to electrodes without disrupting their size distribution. Therefore the local concentration of the particles can be controlled by the present technique.

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The local NMR sensor consisting of the planar surface coil of 0.8mm and 2.0mm outside diameter and a permanent magnet was developed to measure local self-diffusion coefficient of water molecular in a polymer electrolyte membrane (PEM) for fuel cell. Using the pulse-field-gradient spin echo method as a pulse sequence in the NMR system, the relationship between self-diffusion coefficient of water molecular in the PEM at 55, 65 and 75℃ and vapor concentration in the N_2 carrier gas was obtained. The accuracy of self-diffusion coefficient of water molecular in the PEM with three different water contents measured by the planar surface coils was evaluated by the comparison with that measured by the conventional solenoid coil.

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Storage of CO_2 to geological formations such as aquifers is considered as one of the possible options for the abatement of CO_2 emission to the atmosphere. Understandings of microscopic two-phase flows in porous media are very important to assess the long-term fate and trapping mechanism of stored CO_2. We had developed a numerical code, which simulates two-phase flow of supercritical CO_2 and water in porous media including the effect of interfacial tension, wettability, density, and viscosity by means of the lattice Boltzmann method. We investigated effect of CO_2 saturation on flow patterns of two-phase flow in a microscopic model of porous media which have highly water-wet surfaces. A present study shows that the interfacial tension affects the relative permeability of CO_2 and its bubble is trapped in porous media as non-wetting phase by capillary forces. Because the non-wetting phase selectively passes through the large pores, inhomogeneous porous structure affects the flow pattern of CO_2.

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Total performance prediction was carried out for a micro thermoelectric power generator employing rectangular-fin elements and regenerative combustion, which utilizes the combustion gas to preheat the working gas. In the analysis, an array of rectangular-fin elements and hot- and cold-side gases were modeled as a fluid-saturated porous medium bounded by a solid wall. After the validation of the porous medium model, quasi three-dimensional simulations considering the heat and electric current flow in the flow direction were carried out. As a result, for element thickness t=0.5mm, it was found that the overall conversion efficiency from total heat input into electrical energy exceeds 3% as a target, at the electrical power to pumping power ratio more than three and volumetric power density more than 30mW/cm^3.

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Selective mass transport technique is a key issue of microminiaturizing the analytical equipment. A particle transport control was developed by using laser radiation pressure generated in a microchannel, by which particles on the order of micron meter are trapped at the laser focused area. In a flow field one or two elliptical shaped laser focused area was generated near a micro nozzle in order to control particles behavior. Ratio of the number of particles that left from single-focused laser radiation pressure was calculated from observed images captured by a CCD camera. In the present experiment, an optical nozzle was made to control the particle concentration using dual-focused laser radiation pressure.

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The effect of the non-condensing vapor bypass flow and the amount of the working liquid was experimentally investigated on the operating limit of the originally proposed method for heat transportation by utilizing the intermittent discharge of the accumulated high-pressure vapor. The analytical result for finding the condition at the occurrence of the operating limit was shown by taking a proposed physical model into account. The condition could be estimated quantitatively by using a proposed new non-dimensional parameter.

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A numerical simulation was carried out to investigate the overall thermal conductance of a forced oscillating flow heat transport tube, which was cooled at the outer surface of the tube. In addition, the influence of oscillating frequency, inner diameter, length of the tube, and the heat transfer coefficient on the overall thermal conductance has been studied. The results indicated the thermal conductance of the heat transport tube was higher than that of a copper rod. Furthermore, it was revealed that the heat transport rate of the forced oscillating flow heat transport tube especially enhanced, in case of the length of the tube was 600mm.

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The performance of oblique-wave heat exchangers is assessed through a series of numerical simulation for the development of high-performance compact heat exchangers. The effects of flow passage aspect ratio, wave amplitude and the Reynolds number upon the pressure loss and heat transfer characteristics are systematically investigated. It is found that the j/f factor is significantly enhanced even in the case of rectangular passages with wider aspect ratios, and that the choice of wave amplitude under a prescribed flow velocity condition is critically important to improve the performance of this type of heat exchangers.

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The cooling method for PC, HD and etc is more important recently as the PC and HD work faster and higher density in the package. As the limitation of the heat transfer with a natural convection is low values, it is need for the cooling to develop new technology for enhancing heat release with the passive method. In this study, the heat and energy transfer mechanism on surface with fine powder coating by a peculiar pyroelectricity material is investigated experimentally with the unsteady temperature measurement at multi-points. In addition, a new heat flux category is 334w/m^2, 548w/m^2 and unsteady experiment. From the results, the effects of energy conversion coefficient are made clear with several embrocated conditions, which the values are 10%-20% in this study.

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In order to improve thermal efficiency of a gas water heater, an additional heat exchanger is required for latent heat recovery from the exhaust gas. In this study, two types of smooth-tube bank heat exchanger with a staggered and inline tube arrangement were installed to a commercial hot water heater with the output of 34.8kW, and the performance was evaluated under a normal using condition. The experimental results were compared with numerical results by a model based on the analogy between heat and mass transfer. The tested heat exchanger satisfied the required performance, which is a thermal efficiency of 89% based on HHV. Experimental results of heat transfer rate showed higher values than the numerical results, though those of condensing rate showed lower values.

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This study focuses on fundamental characteristics of DME combustion, aiming at the development of low-NOx multi-ports burner. Multi-ports burner consists of a fuel-port and surrounding multi-air-ports. The strong re-circulation flow is formed by the small air jets, thus the short flames form a cluster on every burner unit so that the thermal NOx generation is significantly suppressed to a very low level. The NOx emission of the DME the newly advanced multi-ports burner was reduced to 40ppm at 0% O_2. With the help of the low-NOx combustion system, referred to as the tube-nested combustion, NOx emission of DME was further reduced to 20ppm at 0% O_2.

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An experimental study has been carried out on the synthesis of carbon nanomaterials using rice hulls and Fe catalyst in methane/air laminar, fuel-rich premixed flames under atmospheric pressure. By placing a pair of porous media on the upstream and downstream sides of the combustion space, excess enthalpy burning was applied to the methane/air mixture. Rice hulls were uniformly scattered on a Ni porous medium with Fe catalyst that was placed in the combustion space. We have investigated the effects of Fe catalyst and the reaction temperature on nanomaterials growth. As a result, it has been found that carbon nanotubes are synthesized in non-luminous region.

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Carbon-pipe electrical furnace was developed in order to generate carbon aggregate by thermal decomposition of vaporized benzene. It was confirmed that this electrical furnace enables to heat gaseous media including no oxygen continuously up to 1800℃. Carbon aggregate was sampled at four steps of reaction temperature between 1000℃ to 1800℃. According to experiments, enhancement of reaction temperature resulted in smaller size of carbon-aggregate with decrease of primary-particle constructing carbon-aggregate structure.

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Based on the first and second report, the residual ammonia circulation system is constructed with the system of the separator and the distiller. The ammonia gas can be dissociated to hydrogen, nitrogen and residual ammonia through the catalyst in the dissociator. The residual ammonia by 13ppm or more causes decrease of the output of fuel cells. In order to separate residual ammonia, it is sent to the separator that uses the fact that ammonia well in water. Water with high concentration of ammonia is divided to ammonia gas and water in the ammonia distiller. Thereby, the circulation system for the residual ammonia can be constructed.

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The effects of heat and mass transfer on the electrochemical reaction in a flat-tube-type solid oxide fuel cell (SOFC) are investigated numerically to achieve higher cell performance. The result of the simulation shows that fuel is not sufficiently diffused in the porous media, and this fact causes shortage of the fuel near the three-phase-boundary, and also increased activation and concentration overpotentials. When the cell length is shorter, the heat loss at the cell inlet makes the cell temperature level lower, and this results in the increases in both activation overpotential and electrolyte ohmic loss. Improved thermal insulation at the cell inlet keeps the cell temperature homogeneous and higher, and leads to a drastic increase in the cell output voltage.

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Lateral distribution of water content in a polymer electrolyte membrane in an operating fuel cell was measured by using three-dimensional magnetic resonance imaging (3D-MRI), which clearly visualized not also lateral water distribution in the membrane but also condensed water in flow channels in the cell. A parallel flow and a serpentine flow were investigated. It was revealed that the membrane near the gas inlet shows lower water content compared to those near the gas outlet in both cases. It was also shown that flow pattern considerably affect water content distribution in the membrane presumably due to plugging the gas channel by condensed water droplet under fuel cell operation.

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Water vapor distribution in a cathode channel of polymer electrolyte fuel cell (PEFC) composed of gas supply channel and porous gas diffusion layer (GDL) is calculated by lattice Boltzmann method (LBM) in order to clarify effect of porous structure of GDL in PEFC on water distribution and dew point of supplied gas. It is shown that porosity of GDL affects maximum water concentration emerged in the GDL, resulting in increase of dew point with decrease of porosity. On the other hand, pore scale in the GDL is less influential on water concentration distribution and its resultant dew point of the supplied gas in the cathode of PEFC.

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This study investigates drying condition for the case when a small fan is added to a free-breathing proton electrolyte membrane fuel cell (PEMFC) operating with dry H_2 and air. Polarization tests were conducted on PEMFCs at cell temperatures between 30 and 50℃. The result shows that the cell performance strongly depends on the cell temperature and the stoichiometric flow-rates of cathode gas. The cell performance increases as cell temperature decreases from 50 to 30℃. In the condition where the air flow-rate is quite large, internal resistance increases due to the progress of drying, but it is compensated by the decreased concentration over-potential. The maximum performance was obtained at a small air flow-rate in a narrow pass between dry-out and flooding. This indicates that the flow rate of the fan should be designed relatively small, if a cell design of avoiding flooding is possible.

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Solid oxide fuel cells (SOFC) are expected to become highly efficient power generation equipments in distributed energy systems. The fuel flexibility of SOFC is attractive for the small-scale power generation driven with the fuel derived from biomass. In general, biomass fuel is composed of some different chemical species. In this paper, the effects of fuel composition on a micro gas turbine ((μGT)solid oxide fuel cell (SOFC) combined power generation system is investigated by using thermodynamic cycle simulation. The power generation characteristics of methane-fueled hybrid system are estimated as the reference case. At the SOFC operating temperature of 800℃ and the pressure ratio of 3.0, the efficiency values of the methane-fueled system is 59% (LHV). The four different fuel compositions, i.e., H_2O/CH_4, H_2/CH_4, CO/CH_4 and CO_2/CH_4, are taken up, and methane content values are changed in the range from 100% to 20% (volume ratio) in the cycle analyses. Throughout the simulation, it is found that the decrease of methane content leads to the performance degradation. In particular, in the cases of CO/CH_4 and CO_2/CH_4, the power generation efficiency values greatly decrease together with the decrease of methane content. Because, increasing carbon monoxide or carbon dioxide content has the decline of hydrogen molar ratio at the anode inlet gas, and then the cell voltage decreases. In contrast to this, steam and hydrogen have less influence on the performance degradation, for steam and hydrogen contribute increasing the mole fraction of hydrogen in the reformed gas. However, higher concentration of steam and hydrogen causes the remarkable efficiency decrease.

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In this paper, we investigate the effects of fuel supply conditions on the power generation characteristics of a small tubular solid oxide fuel cell (SOFC), In the experiments, the furnace inside temperature is fixed at 800℃, and the hydrogen/nitrogen mixture (10%/90%) is fed into the single cell as the fuel with the different flow rate conditions. The results show that the flow rate affects the current-voltage characteristics, that is, the net voltage becomes higher with increasing the fuel flow rate. The data of the fuel utilization and the power generation efficiency at the operating points, which give the maximum power output individually, are estimated. Under the operation with 10% hydrogen, the power generation efficiency reaches to 9.0% with the fuel flow rate of 20mL/min. But lower fuel flow rate condition, the fuel utilization and efficiency greatly decrease simultaneously. In addition, by using current interruption method, the detail of the voltage drop is estimated. It is found that the fuel flow rate does not quite affect the ohmic loss.

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A fuel supply system with a short response time is proposed. The time lag occurs when the fuel passes some processes to generate hydrogen. The system of hydrogen generation and the supply system were designed by investigating the time lag in order to obtain the necessary amount of hydrogen corresponding to the gas pedal. When the gas pedal is pressed, the motor rotates with the electric power of the fuel cell and the battery. Then, the voltage of the battery lowers, and the signal to generate more hydrogen is sent to the flow controller. So the vaporizer and the reformer are heated based on the signal. Furthermore, the signal is fed back to thermo controllers, if the supplied fuel has not reached the proper temperature.

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In the paper the small decentralized system is proposed as a hybrid power generating system with a fuel cell and a solar panel. The solar panel is set up on the roof of the system. In the daytime electricity is generated by the sunlight, and water is separated into hydrogen and oxygen by the remained electricity. In the nighttime electricity is generated by the fuel cell with the hydrogen and the oxygen. The hybrid system is proposed to be applied to traffic signals. The signal system is advantageous at the time of the power failure due to emergency such as the earthquake and so on.

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The authors investigated the effect of the shape of solid sample on the specific heat measurement using differential scanning calorimeter. Samples were two synthetic sapphire disks 3.5mm in diameter, alumina particles 75μm in particle size and the composite material made mostly from plastic waste and fly ash. The granular sample of the composite, which was grated, had a maximum grain size of about 0.5mm. The surface of sheet sample of the composite was polished with the sandpaper. The reproducibility of the data for the disk and sheet samples was better than those for the granular sample. The measurement accuracy was affected by the heat transfer inside the sample and at the boundary between the sample and capsule surfaces.

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To examine influence of microstructure made on an emitter surface, spectrally selective property of the emitter was investigated through numerical simulation and experiment. In the simulation, thermal radiation from solid surface is dealt as hemispherical emission from point sources and Maxwell's equations are solved using CIP method. It was demonstrated that around the wavelength corresponding to the normal mode of cavity resonance, emissivity of the emitter could be amplified, while at wavelengths corresponding to the higher modes, emissivity didn't increase. The results indicated possibility of spectral control by making use of the microstructure on the emitter surface. Furthermore, to verify the validity of simulation results obtained, rectangular microcavities (0.5×0.5×0.5μm^3) were made periodically on nickel emitter surface (2.0×2.0mm^2) through photolithography and fast atom beam etching techniques. Heating of sample was conducted in a vacuum chamber to avoid oxidation and spectral emissivity was measured in the near infrared region. The measured spectral property showed cutoff effect at 1.0μm and amplification of emissive power below that.

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The high efficient co-generation system called DREAMS (Distributed Residential Energy with Advanced Management System) is proposed to a multiple dwelling house. The key technology of this system is to connect home and home with one loop of heat transfer line of one inch diameter, and to level the heat demand by a heat storage unit in each house. This system require compact and high response heat storage unit. To increase heat storage density, a use of phase change material, paraffin wax, is examined. In this case, suitable melting point should be selected in each user, because the temperature of hot water to each user may be different. In this study, solidifying characteristics of three kinds of paraffin wax were visualized by using a transparent small vessel, and a numerical simulation based on thermal conductivity model, in which the latent heat of the phase change material was considered as overall specific heat by DSC measures, and the results were compared with the experimental results.

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We have developed a new measurement technique for liquid viscosity using the use of the pulse carbon dioxide laser (wavelength 10.6μm, pulse width 50ns, power 65mJ) as a heating source. In the present method, interfering laser beams heat a liquid surface and generate a laser-induced capillary wave (LiCW) caused by a spatially sinusoidal temperature distribution. The temporal behavior of LiCW is detected by monitoring the intensity of diffracted probing beam (He-Ne laser, 15mW) at the heating spot. The dynamics of LiCW provides information regarding thermophysical properties such as viscosity and surface tension. In the present study, in order to examine the validity of this method, we have measured the viscosity for several pure samples ranging from 0.1mPa's to 10000mPa's.

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In the present study, a water-piston engine driven by the low temperature waste heat is developed and numerical simulations and experiments are conducted to establish the steady operating condition. Both numerical and experimental results show that present experimental apparatus is not capable to attain the steady oscillation state. However, these results show the importance of the appropriate balance between the amount of supplied steam and condensed water in water-piston engine. Additioionally, numerical results and experimental results demonstrate the availability of intermittent steam supply equipment and upper vertical tube cooling devices, respectively. Hence, the experimental apparatus will be improved based on present results in the future.

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