Measurement of surface temperature by an infrared thermometer was discussed for an issue involved in measuring thermal conductivity and thermal diffusivity of biological or soft materials. The effect of degraded spatial resolution in temperature measurement resulted from the cross-talk between photodetectors was examined quantitatively. The temperature that would be measured by using the infrared thermometer was estimated by convolution integral based on the profile of spread output observed at neighboring pixels which was calibrated with a specially designed experiment. The temperature significantly depended on how the cross-talk was taken into account implying the importance of the method of approximation.

View full abstract

The present paper discusses the validity of experimental apparatus for measuring the effective thermal conductivity of metal hydride by the steady heat flow method. We measured the thermal conductivity of Polyacetal whose thermal property is already known to confirm the validity of experimental apparatus. The average value of experimental results is 0.31 W/m-K. The difference between this value and the literature data of 0.23 W/m-K is 10^<-2> order, so that the measuring accuracy of experimental apparatus is sufficiently high. The reproducibility of experimental results is sufficient since the maximum difference among the experimental results is only 0.06 W/m-K under the same condition. The results obtained in our experiments indicated that the experimental apparatus is reliable as the measurement apparatus of effective thermal conductivity of metal hydride.

View full abstract

In the present study, to discern the complex flow structures in a sphere-packed pipe (SPP), digital holographic PTV visualization is carried out by a refractive index-matching method using a sodium iodide (Nal) solution employed as a working fluid. Hologram fringe images of particles behind the spheres can be observed, and the particles' positions can be reconstructed by a digital hologram. Consequently, 3-D velocity-fields around the spheres are obtained by the reconstructed particles' positions. The velocity between pebbles is found to be faster than that in other regions, with the result that the velocity in the other region can contribute to the thermal enhancement in thin thermal layer such as in the case of high Pr number fluid flow.

View full abstract

The demand to measure and understand thermal transport at the nanoscale is increasing recently with needs to control heat conduction by nanostructures. In this study, we have attempted to probe quasi-ballistic thermal transport by time-domain thermoreflectance measurements taking advantage of the plasmon resonance of gold nanoislands. The gold nanoislands are casted onto a sample surface by vacuum evaporation method, and then annealed at 500℃, 700℃, and 900℃ in order to change the contact area between the gold nanoislands and substrate. The contact area was found to shrink by raising the annealing temperature from 700℃ to 900℃. The size-dependent thermal conductivity of GNI/fused quartz and GNI/Sapphire agrees with a solution of the Boltzmann transport equation.

View full abstract

Biochemical calorimeter with MEMS thermopile sensors have been studied for monitoring the detailed process of the biochemical reactions with a minute sample. We have developed a flow-type biochemical calorimeter which can measure the thermal reactions through the whole biochemical processes. The flow-type calorimeter consists of a MEMS differential thermopile sensor, a pair of micro channel reactors in a PDMS layer and a three-fold thermostat chamber. The flow-type calorimeter was tested with the dilution of NaCl aqueous solution to water. And the tests showed that the flow-type calorimeter can detect exo- and endothermic reaction over 250 nW for solution flow rate of 0.05〜1μl/min with the settling time of about 5 minutes. Moreover we also noted the unique method of making dramatic progress of throughput in calorimetry, called "Active calorimetry". It was confirmed that the active calorimetry can enhance the response 10 times higher.

View full abstract

The objective of this study is to investigate heat utilization systems using geothermal and ground source heat. A ground source heat pump (GSHP) uses pipes which are buried in the ground to extract heat from the ground. The conventional GSHP system adopts an indirect heat exchange method using a closed loop and vertical borehole system. On the other hand, the other GSHP system adopts the direct expansion method for exchange of heat with the underground. However, there is few report of a performance data of the GSHP using the direct expansion method so far. This paper described the experimental results of the performance not only of the conventional GSHP system but also of the direct expansion GSHP system.

View full abstract

We evaluated the one-dimensional (radial direction) and two-dimensional (radial and axial direction) thermal analysis models of the ground heat exchanger with the remarkably short foundation piles (Length: 5 m). The thermal performance of the traditional borehole ground heat exchanger is equivalent with one-dimensional and two-dimensional analysis. However, the thermal performance values of remarkably short foundation piles obtained in a continuous run from those calculation results. The results show that it is important to design the thermal performance of the remarkably short foundation piles.

View full abstract

Effects of natural convection on coaxial tube ground heat exchanger was investigated by experiment and numerical simulation. Heating a fluid in upward flow through the annular channel (or cooling in down ward flow) resulted in an increased velocity gradient near the ground side wall, thereby increasing the heat transfer rate and heat transfer coefficient. Heating a fluid in downward flow (or cooling in upward flow) has the reverse flow near the ground side wall, and flow temperature is closer to ground temperature. Hence the heat transfer rate and heat transfer coefficient decreased in these case.

View full abstract

Thermodynamic property model explicit in the Helmholtz energy is presented for the R-32/1234yf mixture. The Helmholtz energy of the mixture is expressed as the sum of the ideal mixture contribution and the contribution from mixing. The most accurate pure-fluid equations of state are incorporated to calculate the ideal mixture contribution. The contribution from mixing is determined by fitting to available experimental data. The estimated uncertainties in calculated properties from the model are 1% for the bubble point pressure and 0.2% for liquid density. The critical parameters of the mixture are reasonably represented with the model.

View full abstract

Molecular dynamics simulations were conducted for a thin liquid film on a nanometer-scale slit pore using the 12-6 Lennard-Jones potential, and the mechanical balance including the pressure and the force distribution acting on the liquid film was investigated so as to elucidate the mechanism of the liquid wetting phenomena of a nanometer-scale slit pore from a molecular point of view. The results show that the z component of the force acting on the liquid molecules in the vicinity of the entrance of the slit becomes weak with the increase of the liquid-solid interaction intensity, although the pressure in the system is constant regardless of the variation of the liquid-solid interaction intensity.

View full abstract

The present study investigated a drying behavior and film formation of a particle suspension droplet on a patterned substrate with a single line-shaped hydrophilic region. The effect of particle concentration in a droplet on the film formation and contact line behavior during drying was examined. The droplet on the patterned droplet showed a slight spread along the line-shaped hydrophilic region. Although a pure water droplet showed a rapid spread on the hydrophilic region near the termination of drying, a particle suspension droplet showed the contact line pinning on the hydrophilic region throughout the drying. This may be because that the particles deposited on the hydrophilic region inhibited the contact line spreading.

View full abstract

Surfactant flooding is one of the enhanced oil recovery processes to recover residual oil from oil reservoirs. It is considered that reduction of interfacial tension by surfactants improves mobility of trapped oil in porous media. However, its fundamental mechanism is not clarified. A measurement technique to visualize the two-phase flow of oil and aqueous surfactant solution in porous media was developed by using refractive index matching method. Therefore, the micro-scale dynamics of oil recovery via surfactant flooding was investigated. Mobilization and coalescence of residual oil droplets were observed through surfactant injection.

View full abstract

Boiling is applied to many industrial machines due to its high heat transfer coefficient. However, a very complex mechanism of boiling, especially bubble nucleation, is still not sufficiently understood. On the other hand, numerous experiments have revealed the existence of soft domains that called nanobubbles at the solid-liquid interface. In this study, to investigate the influence of the solid-liquid interface nanobubbles on the bubble nucleation of boiling, an atomic force microscope is used to characterize the morphology of nanobubbles. The temperature dependence of the nanobubbles and temporal changes are also observed.

View full abstract

The relationship between the OH^- concentration of mixing solution and the electrostatic potential at the liquid-liquid interface was investigated. Two kinds of fluorescent dye whose concentration changes depending on the electrostatic potential were introduced in the aqueous solution. An evanescent wave excited the fluorescent dye in the vicinity of the interface, and nano color imaging, which is based on nanoscale laser-induced fluorescence, was used to acquire the fluorescent intensity distribution. The OH^- concentration of the mixed solutions was formed to vary spatially, gradually reducing from the side of the higher pH solution to the lower pH solution. The result indicates that the electrostatic potential changes depending on the spatial OH^- concentration.

View full abstract

For the investigation of ion motion in mixed electrolyte solutions, a non-intrusive sensing technique was developed using coherent anti-Stokes Raman scattering (CARS) generated by a femtosecond pulsed laser. This technique, CARS microscopy, provides rapid quantitative information from molecular vibrations with high spatial and temporal resolution. Two experiments were conducted, with pure electrolyte solutions of sodium sulfate and ammonium chloride used for the first experiment and mixed solutions with both substances used for the second experiment. In each experiment, the relationship between the ion concentration and the CARS intensity was investigated. A reference value was obtained and the CARS intensity ratio was calculated to eliminate the influence of fluctuations in the CARS intensity.

View full abstract

We have proposed a method for measuring thermal conductivity of gases and liquids using a micro-beam MEMS sensor which is 〜10μm long and 〜0.5μm wide. Concerning the effect of rarefied gas due to the small size of the sensor, we conducted experiments with several types of gases at lower pressures. The results suggested that the measurement of HFC-32, Ar and N_2 at the atmospheric pressure is feasible, while that of He would give much lower thermal conductivity than the literature value. The effect of rarefied gas on the heat conduction from the sensor to gases was also examined as a function of the Knudsen number.

View full abstract

This paper proposes a non-intrusive measurement imaging technique of solution composition at liquid-solid interfaces using spontaneous Raman scattering excited by evanescent wave. The evanescent wave was generated at a glass-solution interface by total internal reflection using an optical system employing two prisms. Total internal reflection Raman spectra of a mixed solution of H_2O and D_2O could be obtained that confirmed the relation between the solution composition and the integrated Raman intensities within the Raman bands of O-H and O-D stretching modes. Future experiments will be performed for non-intrusive measurement of the composition of mixed solutions at liquid-solid interfaces using Raman scattering images.

View full abstract

The present study describes the development of a molecule concentration measurement technique in gas flows by using Coherent anti-Stokes Raman scattering (CARS). The wavelength difference of the excitation beams were adjusted to coincide with the vibrational energy level of the sample molecules under measurement to obtain CARS signal. CARS was generated from a mixture of N_2-CO_2 injected into a chamber. The CARS intensity was measured for several mixture ratios, and its relationship to these ratios was obtained. The results indicate the viability of concentration measurements in reaction zones formed in microscale gas flows.

View full abstract

Mass transport in the vicinity of solid-liquid interfaces exhibits complicated characteristics and an essential understanding of their mechanism is of critical importance. The interfaces between SiO_2 and water or IPA (iso-propyl alcohol) are typical system in the semiconductor industry. In the present study, we investigated molecular-scale structures of the adsorption layers of liquid molecules and molecular transport characteristics by using molecular dynamics (MD) simulations in order to clarify the mass transport in the vicinity of the interfaces between SiO_2 and liquids. As typical terminations of SiO_2 surfaces, H- and OH- terminated ones were used and self-diffusion coefficients in the direction parallel to the interface were measured and the mass transfer properties were discussed.

View full abstract

In this study, two-dimensional hexagonal mesoporous silica thin films of SBA-15 were synthesized via dip-coating using an evaporation-induced self-assembly process. The effect of the withdrawal speed on the thickness of the films, one-dimensional pore alignments and two-dimensional hexagonal pore arrays was elucidated. The film thickness increases with increasing withdrawal speed and also increases upon decreasing the withdrawal speed to ultraslow region where capillary rise of the solution occurs. Detailed analyses of FE-SEM and TEM images and XRD patterns of the synthesized thin films clarified that the pore sizes and interplanar spacing also depend on the withdrawal speed; this suggests that the film thickness and hexagonal pore-array dimensions can be controlled without changing the physicochemical properties of the silica precursor solutions or the sizes of the template molecules.

View full abstract

Phase change of erythritol confined in highly ordered mesoporous silica SBA-15 was studied by differential scanning calorimetry (DSC). Mesoporous silica SBA-15 particles with three different pore radii (3.76, 4.15 and 4.61 nm) were synthesized by changing the aging temperature. The DSC curves of erythritol and the mixtures of erythritol and SBA-15 particles were measured. The measured DSC curves showed that the endothermic peak of erythritol confined in SBA-15 appears at lower temperature than that of pure erythritol and the peak shifts to lower temperature with decreasing the pore radius. Furthermore, the influence of thermal history on the melting and freezing points of erythritol confined in SBA-15 was clarified.

View full abstract

Atomic molecular dynamics of bulk liquid crystal state of 4-pentil-4'-cyanobiphenyl (5CB) system were performed. For the coulombic interaction treatment under the periodic boundary conditions, Particle Mesh Ewald (PME) method and Isotropic Periodic Sum (IPS) method were applied. In both cases, the system was ordered from 280K to 290K. However the ordering processes were different between the two cases. When the temperature was fixed to 280K, the result from PME showed layer structure, whereas IPS did not. The mean square displacement of PME drastically changed between 280K and 290K.

View full abstract

Clathrate hydrates are crystalline compounds enclosing guest substances in cages that are formed by hydrogen bonded water molecules. They are expected as various types of industrial applications. Methane is one of the most important guest substance of clathrate hydrates and the understanding of the mechanisms of nucleation and crystal growth from methane and liquid water is significant for the hydrate applications. Molecular dynamics calculation is a suitable method for the observation of nucleation and crystal growth in molecular level. We focused on crystal growth after nucleation and carried out the molecular dynamics simulation of the crystal growth of methane hydrate on the water/methane surface and analyzed in molecular level. In this work, we achieved the growth rate along the water/methane interface is larger than that in the bulk water.

View full abstract

We prepared porous films using micro-phase separation of block copolymer and selective etching process. We measured the cross-plane thermal conductivities of various processed thin films by using a differential 3ω method. Thermal conductivity of micro-phase separated BCP1 film was 0.25W/(m・K), the value was 19% higher than that of as casted BCP1 film. The thermal conductivity of the thin film was increased for molecular orientation of polymer chain. Thermal conductivities of porous films were the lower than those of both casted films and micro-phase separated films. We controlled thermal conductivities of block copolymer films by using the molecular orientation and the porosity.

View full abstract

In the present study the quantum molecular dynamics method was applied to an energy transfer problem to an electron during a particle surface collision process in order to elucidate how the energy of the particle collision transfers to the emitted electrons and to develop the applicable simulation method for such small energy transfer phenomena. The effects of the collision energy on the energy transfer to an electron were investigated by the non-adiabatic quantum molecular dynamics method when a xenon molecule was collided with the surface so as to elucidate the predominant factor of the energy transfer to the emitted electron.

View full abstract

Effective thermal conductivity with radiation is analyzed by the homogenization method. This method can precisely represent the microstructure of a packed bed. In this study, the effects of parameters such as the radiation emissivity, temperature and particle size of the packed bed on the conductivity have been estimated to clarify the mechanism of complex packed structure. For example, heat transfer by radiation does not dominate if the material has voids of less than 1mm in size. Moreover, by comparing a conventional model and the homogenization method, applicability of their models were shown for estimating the effective thermal conductivity.

View full abstract

Electric Vehicle (EV) motors have the problem on heat removal. Arranging thermal-hydraulic characteristics in the motor is required. However, heat transfer characteristics in an EV motor is not clarified. The aim of the present study is to develop a means of predicting the temperature in the coaxial cylinders. In the present study, thermal network is introduced. With experimental apparatus simulating an EV motor, temperature at every part is measured. We build the thermal network in the experimental apparatus. We estimate the thermal resistance between every part., and evaluate applicability of the thermal network for coaxial cylinders.

View full abstract

This paper investigates transient temperature behavior at microprocessor silicon die hot spot. The thermal local resistance is defined as a part of one-dimensional thermal network and is utilized to express microprocessor silicon die hot spot temperature. Transient thermal local resistance is modeled and is evaluated based on and compared to three-dimensional heat conduction simulation result.

View full abstract

Single-phase heat transfer characteristics of nanometer-sized diamond (nano-diamond) dispersed nanofluids have been investigated experimentally. The effective thermal conductivies of both water and ethyleneglycol base nano-diamond dispersed nanofluids obtained by the transient thin hot wire method were increased around 2-6% comparing with base fluids. The obtained values were in good agreement with the estimated values of the Hamilton-Crosser equation. Heat transfer enhancement could be achieved by using the nano-diamond nanofluid as single-phase heat transfer cooling fluid.

View full abstract

3D devices which contain two or more chips stacked vertically and connected by through silicon via (TSV) will be required for high performance computer (HPC) systems. However heat dissipation is a critical issue because 3D devices are difficult to cool lower layer chips. In this paper, cooling behavior of 3D devices mounted on a printed circuit board (PCB) with thermal vias and thick Cu layer is studied. It is confirmed that thermal vias and thick Cu layer are effective to cool lower layer chips in 3D devices.

View full abstract

A thermal design for lithium-ion battery packs with the world's highest volumetric energy density for use in power storage systems is described. The 130L battery pack's maximum load conditions during charging and discharging were obtained by a histogram analysis of our wind turbine system. We fabricated long, thin battery modules for natural convection cooling by laminated battery cells. As a result of our designed clearance ratio between modules and the setting of slanted airflow guides between modules, we achieved target temperature rises of less than 15K.

View full abstract

A microgroove evaporator is expected to realize a high heat transfer coefficient despite its simple structure. However, the thermal transport properties cannot be predicted from the groove structure, so far. In this research, we propose the revised numerical simulation model for predicting these properties by assuming a one-dimensional flow along the axial direction of grooves. Moreover the calculated meniscus profiles at the cross section of groove are validated by comparing the calculated profiles and the microphotos of meniscus profiles. The calculated meniscus profiles have shown good agreement with the experimental microscopic observation. The effects of the groove width on the calculated capillary length and rate of transported heat have also been discussed.

View full abstract

In highly subcooled boiling of water, micromubble emission boiling, MEB, occurs and the heat flux increases higher than the ordinary critical heat flux. Subcooled boiling is performed for a mixture of water and Ethylene-glycol for practical condition of EV cooling system. MEB is generated stably and the maximum heat flux is 3.0〜3.4MW/m^2 (300〜340W/cm^2) at 198〜208K of wall temperature for 50vol% of Ethylene-glycol and 40K of liquid subcooling under the atmospheric condition. Small hysteresis is observed in boiling curves with microbubble emission. The experimental results show that MEB is effective for a high heat flux cooling technology in power electronics.

View full abstract

For energy saving of the servers, we applied the loop-type thermosyphon to CPU cooling. It is necessary to choose the high-performance boiling surfaces to enhance the performance of thermosyphon. Therefore, we have compared the pin-fin and TE-E as high-performance boiling surfaces in condition that they have , been put in real thermosyphon. As a result, the performances of both are equal in the condition that liquid level enough. In addition, they can cool the CPUs in degree of superheat less than half of the flat plate. However, the pin-fin has not worked enough performance in a condition with a little quantity of water.

View full abstract

The new cooling structure using thermo siphon is developed for network devices. By using our proposed new cooling structure, air flow direction can be optimized corresponding to servers layout. This results in reduction of number of cooling fans as well as energy consumption. In practice, we need to consider to cool multiple control circuit boards. In this study, we utilized four heaters responding control circuit boards. From our experimental results, we observed placing heaters close to the radiator located at the downstream position provides the best cooling performance.

View full abstract

Recently, the heat flux of electronic devices increases with rapid development of the semiconductor technology. So, a high performance cooling unit for electronic devices is required. Therefore, we have experimentally investigated the cooling performance of the loop type thermosyphon. In this paper, effects of working fluids on heat exchange performance of this loop type thermosyphon were evaluated in the heat flax ranges from 15W/cm^2 to 135W/cm^2. Two HFO refrigerants and one HFC refrigerant were tested for working fluid. The boiling thermal resistances of two refrigerants are nearly the same and less than that of the other refrigerant.

View full abstract

We have been developing an improved in-plain thermal conductivity measuring method of flat plate specimen such as printed wiring board (PWB) named as "quasi-steady state straight fin temperature fitting method" in which transient temperature data are used to obtain temperature dependency of the thermal conductivity of the specimen by only one time heating. We demonstrated the accuracy of the measurement method by experiment and numerical simulation. Three kinds of metals such as pure copper, pure aluminum and stainless steel were used as specimens in which fin efficiency were ranged from 0.09 to 0.75. The following conclusions were obtained from the experiment and the numerical simulation. (1) As specimen temperature rises, the temperature profile changed analogously after a certain time after start of heating. (2) The temperature profile reached steady state condition at 3600s after heating but thermal conductivity obtained by this method showed constant value after 400s. (3) The effective thermal conductivity obtained by this method agreed with the literature data within ±10% dispersion in the fin efficiency ranges of 0.2〜0.8.

View full abstract

We have developed an identification method of thermal quantities for high accurate thermal simulation of a power semiconductor module. Thermal quantities are extracted by the inverse analysis from transient thermal resistance, which includes all information of a thermal path from junction to ambient and is an only quantity we can measure with a high degree of accuracy. In order to execute the inverse analysis efficiently and stably, we have adopted a genetic algorithm which is one of optimization techniques. It has been verified that the developed method works well with the test model.

View full abstract

As smart phones become more complex, higher in performance and smaller in size, heat concentration at localized areas is becoming a problem. Therefore, the aim of this paper is to examine the effect of high thermal conductive materials for heat dissipation in order to solve this problem. The thermal conductivity of the outer case of the smart phone was changed using finite element method (FEM) to simulate high thermal conductive materials or composite materials with anisotropy. The maximum temperature gradually decreased and the minimum temperature gradually increased with increasing the thermal conductivity of the outer case. Moreover, the thermal conductivity in the longer direction of the smart phone was important for lowering the maximum temperature. In this paper, it is found that applying high thermal conductive materials to the outer case is effective for uniforming the heat dispersing.

View full abstract

Heat transfer from electronic equipment with high packaging density or electric equipment with highly heated portions, not only heat conduction, convection, and thermal radiation but also thermal contact conduction is also involved, and those modes are coupled intricately. In order to make reasonable thermal countermeasure and design of such equipment, it is important to predict the thermal contact resistance accurately. In this study, the thermal contact resistance of solids with wavy rough surfaces has been investigated theoretically and experimentally under the low mean contact pressure of 0.1MPa to 1.0MPa.

View full abstract

This paper describes a study on natural convective cooling in electronic casing with outlet. In recent years, heat generation density in electronic devices has been becoming significant due to miniaturization and high performance. High density packaging does not allow to include cooling fan because of insufficient space, and natural convective cooling becomes important for development of electronics. In this paper, fundamental natural convective cooling ability in electronic casing with outlet is discussed by using CFD analysis. As a result, higher cooling ability can be obtained with increase in the distance between heat source and outlet.

View full abstract

In order to meet the recent demand for downsizing of the electronic equipment, the miniaturization and the improvement in heat transfer performance of heat sink in natural air-cooling are required strongly than ever. From previous studies using large sized heat sink, it has been revealed that the heat sink performance depends on the pin size and the population density of pin. However, there seems almost no report focusing on pin parameters alone. In this study, the effects of pin size and the population density of pin on the heat transfer characteristics of small sized heat sink, especially with the pin height and pitch from several hundred micro meters to a few millimeters, have been investigated experimentally.

View full abstract

Reduction of thermal resistance of naturally-cooled cooling system has been investigated. Pin-fin type heat sink was utilized as to clarify the effect of pin arrangement on the thermal performance of heat sink. The pitch of fins was set 1, 2, 3, 4, 5mm where the surface area of all heat sink was set as the same. The results show that the thermal resistance of heat sink decreases with increasing pitch of fin arrangement from 1 to 4mm, whereas the thermal resistance gets increase when the pitch was set 5mm. The results also show that even the slight decrease in fin efficiency causes the increase in the thermal resistance.

View full abstract

The porous microstructure of SOFC electrodes significantly affects the SOFC performance. It is necessary to understand the diffusion process through the complex microstructure in order to improve the performance of SOFC. 3D-printed enlarged models based on practical microstructure of SOFC anode obtained by FIB-SEM observation were prepared for possible application to diffusion experiments. The 3D models were evaluated in the point of gas tightness and strength. Furthermore, reproducibility of the complex microstructure by a 3D printer was tested by examining the difference between the original FIB-SEM data and the 3D-printed microstructure. The result shows both the possibilities and limitations of this method.

View full abstract

An anode-supported honeycomb SOFC can achieve high power density and improve thermo-mechanical durability at high temperatures. We have fabricated the honeycomb cell with an electrolyte layer of 8YSZ on an anode honeycomb substrate of Ni/8YSZ. The cathode layer is LSM-YSZ composite. Current-voltage and current-power density characteristics of the cells having different anode and cathode flow channel configurations are measured under different hydrogen flow rates and partial pressures. We also evaluate the hydrogen mole fraction distributions in the honeycomb cell using finite element method, and discuss appropriate anode and cathode flow channel configurations.

View full abstract

Fuel starvation in the downstream part of the flow channel in a solid oxide fuel cell decays the cell performance giving rise to current distribution. In particular, this behavior is complicated in the case of the hydrocarbon fuel. Elucidation of the current distribution is therefore required to optimize the gas flow condition under operation, and to develop new cell design and diagnosis method for the distribution. We have thus measured the current distribution in an anode-supported microtubular cell having segmented cathodes under different fuel flow rates at around 800℃.

View full abstract

The burner to establish 2x2 array of microflames of DME with air coflow around each microflame has been developed and applied to a direct flame fuel cell. This power generation system has been tested and showed that the max power density is attained at corresponding equivalence ratio of 1.45 and at fuel flowrate of 60 sccm. The obtained optimum max power density is 0.49W/cm^2, which is better than previous studies. However, the conversion efficiency is only 0.46%, which means that it needs to become at least 4.3 times larger to have larger energy density than that of lithium polymer buttery.

View full abstract