We investigated interaction phenomena between a solidification interface and a nanoparticle conducting the non-equilibrium molecular dynamics simulation for a system which consists of a Si nanoparticle and water molecules. The solidification was caused by controlling the temperature in the system, and we investigated the influences of interaction strength between the nanoparticle and water molecules and cooling temperature on the interaction phenomena. It was observed that the nanoparticle sticks to the solidification interface in the case of a relatively strong nanoparticle-water interaction, on the other hand, the nanoparticle is pushed by the solidification interface in the case of a weak interaction.

Numerical simulation of convection heat transfer from airfoil-shaped tube by using OpenFOAM. OpenFOAM is a C++ toolbox for the development of customized numerical solvers and processing utilities for the solution of heat transfer. Flow and temperature fields are calculated and compared with those of cylindrical heat tube. Reynolds number based on equivalent diameter and approaching velocity is set to be 10, 100, 200. So the field is assumed to be two- dimensional flow. It is found that the ratio of Stanton number and drag coefficient St/C_D of airfoil-shaped tube is larger than that of cylindrical tube.

Transparent materials have been gaining more and more attention in a wide range of applications, such as ICT equipment and energy conversion devices, with continuously increasing demand in the future. Such applications require micromachining of the materials that conventional mechanical machining cannot achieve. Although the pulsed laser machining is most promising, further understandings of the basic phenomena is needed. In this study, we conduct the experiment and the calculation of nanosecond pulse laser machining of fused silica. In addition, we conduct high speed visualization of plasma during processing because plasma shielding is a problem for laser machining.

In surface temperature measurement by thermocouple, measurement error was quantitatively investigated when the temperature measuring junction was adhered to the surface and a part of the lead wire was placed on the isothermal surface. In this paper, heat paths of a thermocouple were modeled by thermal-resistance-network. Unknown parameters related to the contact between the thermocouple and the surface were estimated based on the measured data. The error ratio calculated by the thermalresistance-network model agreed well to the experimental data both quantitatively and qualitatively, which indicates the validity of this model.

Heat transfer between the high temperature fluid and the cylindrical ceramic capsule and the melting process of the PCM inside the capsule were experimented and simulated. Realizable k-ε turbulence model is used in this simulation. Numerically solved results showed trends consistent with the experiment. In the down flow, it was confirmed that the melting front is like a conical shape because the near-wall-fluid temperature on the upstream side was high. It is found that the heat transfer coefficient between the hot air and the ceramic capsule depends on capsule height.

Improving heat storage system is needed to effective operation for concentrate solar power.

In order to consist and evaluate packed-bed latent heat storage system, melting experiment of phase change material (PCM) inside a ceramic container in forced convection is operated. An axisymmetric model of heat transfer and fluid flow during melting process on forced convection based on the experiment is analyzed.

PEFC(Polymer Electrochemical Fuel Cell) has been introduced in household and automotive applications. One of the problem of PEFC to be solved is its cell performance improvement. In this research, we focused on the improvement of oxygen and proton transport properties in catalyst layer. From mass transport point of view, the ideal cathode catalyst layer should have different structure for the membrane-side and Gas Diffusion Layer, GDL-side. In this report, Oxygen and proton transport properties in cathode catalyst layer was analyzed and the effect of mass transport properties on cell performance was investigated by evaluating oxygen and proton transport resistance that is obtained from measurements and by optimizing ionomer density of multilayered catalyst layer(I/C ratio).

Clinical analytes, which are used for early detection of disease, are rapidly deteriorated. Thus, the preserving the quality of such analytes is highly required. Preservation of clinical analytes with the room-temperature desiccation is an ideal preservation method, although controlling the moisture in a specimen with a glass forming bio protective substance, e.g. trehalose, is essential for the drying process to be successful. In this study, the temporal change of the water concentration distribution in the high concentration aqueous solution of protective agents during the drying process was measured by microscopic infrared spectroscopy using infrared absorption band specific to water. Based on the temporal change of the water concentration distribution, the water self-diffusion coefficient in the high concentration trehalose and ε-poly-L-lysine(PLL) aqueous solution was estimated.

The distribution of carbon deposition on fuel electrode and degradation of power generation performance in the internal reforming solid oxide fuel cell (SOFC) supplying methane and steam to the fuel electrode were observed. The result show that the degradation in the case of thin fuel electrode is larger than that in thick and the peak of carbon deposition is detected in the range of 10 μm from the fuel electrode surface. In the case of thick fuel electrode, the area where is under about 20 μm from electrolyte can’t observe the obvious carbon deposition.

In order to measure fluid temperature fluctuation accurately in turbulent flows by a fine-wire temperature sensor (cold-wire), we usually need to compensate for the sensor response appropriately based on its dynamic response characteristics. In the present study, we use a very fine temperature sensor of 0.25 μm in diameter to measure a turbulent thermal wake flow behind a circular cylinder. Thanks to its extremely high response speed, the outputs of the ultimately fine-wire sensor do not need the response compensation. It is demonstrated that the power spectra, r.m.s. values and instantaneous signal traces of the temperature fluctuations can be measured accurately by comparing the results with those obtained by the response compensated cold-wire sensor of 3.1 μm in diameter.

In recent years, various types of Immersed Boundary Method (IBM) have been studied quite extensively. The IBM has many advantages. However, there are few examples which investigated a heat transfer model using the IBM. It is useful if we can compute the flow and heat transfer around any shape of object accurately. We carried out computations of Blasius flow with heat transfer using an IBM we proposed. We perform qualitative evaluations. We confirmed difference in precision by a plate angle. We have to introduce a method which improved not to depend on a plate angle.

Performance of autonomous power unit with coupling catalytic maicrocombustor was investigated with varying the fuel flow rate and the driving voltage of the micro-blower, which controled to air flow rate. According to the result of element experiments, the maximum net output of the power unit was expected about 180mW at fuel flow was 7.5sccm and driving voltage was 11V. Under these conditions, the power unit actually generated the net output electricity 249mW. The final conversion efficiency of the total system reached 1.92%.

The evolution of viscous fingering in a porous medium was visualized three-dimensionally. Nonlinear interaction between fingers such as tip splitting, shielding, and coalescence was observed. As the viscosity ratio increases, the finger structures become very fine. However, the tip position of the finger does not change. When the injection rate is high, the dispersion effect becomes remarkable due to the unsteady motion of the fingers, and the number density in the fingers decreases.

This paper provides a new methodology for measuring heat flux with “net” heat flux sensor utilizing the Peltier device to enable heat feedback control. The advantages of this sensor are that the removal heat on the cooling surface of the Peltier element shall be controlled electrically, and the surface temperature of the sensor can be controlled arbitrarily. The static performance of the sensor was examined by comparing the measurement with the incident heat flux by a cone heater under various conditions. The result shows fairly good agreement. Therefore, verification are well-confirmed.

A pulse injection method was demonstrated to control ionomer distribution in catalyst layers of polymer electrolyte fuel cells (PEFCs). Ionomer dispersion was intermittently sprayed onto the catalyst layers and then was dried in a controlled atmosphere in order to fabricate structurally-controlled catalyst layers. Through-plane ionomer distributions of the catalyst layers analyzed by energy dispersive X-ray spectroscopy revealed that formation of an ionomer layer on the catalyst layer was controlled by adjusting an injection time. It was also shown that spayed ionomer could diffuse into the catalyst layer primarily filled with n-propyl alcohol, resulting in a graded ionomer distribution in the catalyst layer.

Fabrication of porous carbon electrodes for the purpose of redox flow battery application are presented. Melt spinning process using centrifugal force was applied in order to produce fibrous electrode for reducing fiber diameter and increasing porosity of the electrodes. Coal pitches were tested as thermoplastic carbon fiber precursor. Melt spinning conditions were investigated. It was shown that mixing coal pitch with creosote, leading to reducing viscosity of melt pitch, worked better for fabricating fibers. Oxidation stabilization and carbonization conditions were also examined and demonstrated fabrication of carbon porous material having electrical conductance as a potential candidate for redox flow battery electrode.

Gas transport properties in polymer electrolyte fuel cell catalyst layers consisted of different carbon materials were evaluated by using a microfluidic device. The microfluidic device consists of catalyst coated membrane and Si chip having parallel microchannels. Air and nitrogen were supplied to the two parallel channels in the device, respectively. Gas transport properties were evaluated by measuring outlet partial pressure of oxygen which was diffused through the catalyst layer. Adding multi-walled carbon nanotube in the catalyst layer instead of carbon black resulted in an increase of effective gas diffusivity, while geometrical porosity was decreased.

To investigate the flame propagation characteristics under a high efficiency spark ignition engine condition, a direct numerical simulation (DNS) of forced ignition of premixed mixtures in a constant volume vessel with a tumble flow has been performed for a lean Toluene Reference Fuel (TRF)-air mixture at a high exhaust gas recirculation (EGR) rate at high pressure. Main flame just after the ignition point shows flamelet-like structure, whereas flames that was split by turbulent motion seem to be in extinction process.

Electromagnetic field around metal-semiconductor-metal (MSM) multilayered thermophotovoltaic (TPV) cell was numerically simulated using three dimensional finite difference time domain method to obtain absorptance of MSM multilayer. In the current study, gold and gallium antimony are assumed to be materials of metal and semiconductor layer, respectively. Even if there is no top metal layer, a peak of absorptance was observed because of optical interference inside gallium antimony thin film. Here, the peak wavelength shifted to shorter wavelength region by placing squared cavity array layer called fishnet layer on the gallium antimony layer. Moreover, the wavelength of first peak of optical interference became shorter with decreasing the width of cavity, so that the absorbing spectral intensity of multilayer became suitable for practical power generation.

The distribution of ionomer which is one of the materials in a catalyst layer affects the performance of polymer electrolyte fuel cells. However, the distribution of ionomer in the catalyst layer is still unclear. Therefore, in this study, we performed the analysis of ionomer distribution in the catalyst layers with the different ionomer-carbon ratio (I/C) by two-stage ion-beam processing. Two-stage ion-beam processing consists of the fabrication of a smooth cross-section of the catalyst layer by a broad ion beam and the selective removal of ionomer by a focused ion beam. Scanning ion microscopic images after each process were obtained and image processing was carried out. The analysis showed that I/C affects the ionomer thickness and agglomerate particle size.

Boiling heat transfer using immiscible mixtures is an innovative cooling method for the cooling of small and large semiconductors operated at high heat flux density. Immiscible liquid mixtures discussed here are composed of more-volatile liquid with higher density and less-volatile liquid with lower density such as combinations of FC-72/Water or Novec7100/Water. To clear the condition of boiling refrigerant transition in pool boiling by immiscible mixtures, the experiments under the conditions of various height of liquid layers are carried out. And a new threshold derived by Helmholtz instability is proposed for the occurrence of boiling refrigerant transition. Experimental results, including data from previous studies, agreed well with newly proposed thresholds.

This paper describes a research on a jet noise reduction device, a chevron nozzle. Chevron nozzles reduce the jet noise by an effect of promoting the mixing of high velocity jet and external flow. However, they tend to cause a thrust loss at the same time. In this research, experiments have been conducted using a small turbojet engine to evaluate the effect of chevron nozzles on the engine performance from both aspects of jet noise and thrust. In this paper, the experimental results of the Nozzle III, newly manufactured based on the results of previous research, have been reported. The comparison of the results of previous research and experimental results of Nozzle III has been made and the effectiveness of Nozzle III has been reported.

It is well known that the bleeding of compressed air is an effective method to avoid an unstable state such as surging in a compressor. A bleed hole has been provided at the compressor exit of a turbojet engine and experiments have been carried out to investigate engine performance changes as a result of bleeding. Also, using the performance analysis tool of gas turbine (GTPAT), a prediction of engine performance has been made based on the component matching theory. The comparison of analytical results with experiment data has been conducted. This paper also presents analytical results regarding how operating points and operating lines move away from the surge line on the compressor performance characteristic diagram due to the compressed air bleeding.

Two phase flow distribution for split flow in Y junction after horizontal to vertical 90° elbow tube are evaluated through experimental and analytical approaches. In the experiment, the dependency of distribution on structural parameters such as orientation angle of elbow tube as well as operating conditions such as inlet flow rate and quality. The distribution in Y junction was found to depend strongly on both orientation angle and split ratio as evaluated in both experimental and prediction model.

Recently, ammonia (NH₃) is attracting attention as a promising hydrogen energy carrier and as a carbonfree fuel in NH₃ direct combustion. It is important to know combustion characteristics of NH₃ and to develop accurate NH₃ reaction mechanism. In the present study, flame characteristics of NH₃/air and NH₃/N₂O mixtures and ignition characteristics of a NH₃/N₂O/Ar mixture were investigated. N₂O was considered here because of an important intermediate in NH₃ combustion. The ignition characteristics of a NH₃/N₂O/Ar mixture were investigated using a micro flow reactor with a controlled temperature profile and a quadrupole mass spectrometer. Numerical predictions computed with the NH₃ chemical reaction mechanism were compared with the experimental data obtained from the present experiments and literature.

This paper discusses diffusive-thermal modeling of premixed-flame propagation with a particular focus on the accuracy of the Kuramoto-Sivashinsky (KS) equation. Numerical solutions of a two-dimensional diffusive-thermal system are compared with those of the corresponding KS equation at various values of a reduced Lewis number, α = β(1 - Le)/2, where β is the Zel'dovich number, and Le the Lewis number. It is found that discrepancy between the two models increases with increasing α. This is an expected result because the KS equation is formally obtained by taking the limit of α → 1.

Ammonia is expected not only as hydrogen energy carrier but also as carbon-free fuel. Fundamental flame characteristics of ammonia/air turbulent premixed flames in a swirl burner need to be clarified in order to realize ammonia-fueled gas turbine combustor with high efficiency, and lower emission level than the emission standards. In this study, flame front of ammonia/air flame in swirling flows were experimentally observed by using OH-PLIF under various pressure, and the flame front characteristics, i.e., local flame surface density and local curvature, were evaluated. It was clarified that the scale of wrinkles on flame front decreases with an increase in pressure.

The main purpose of this study is how water injection on a micro gas turbine engine contributes to the recovery of power output. Especially in summer, the density of air tends to decline, compared with one in winter. This phenomenon causes the decline of power output. Water injection is known for an effective tool of recovery of power output. The experiments have been performed to investigate the behaver of power output of a micro gas turbine due to the change of injection ratio. The injection ratio has been varied within the range of 1.03% to 4.49%. The evaporation rate of water droplets is calculated based upon mass transfer between water droplet and surrounding air flow.

The prediction method has been reviewed by comparing the predicted performance with the measured data.

Based on visual observations of refrigerant gas-liquid flows in a multi-pass channel that simulated a parallel-flow type evaporator, we examined qualitatively the effect of the multi-hole distributing pipe inserted in the dividing header on the uniformity of liquid distributions to branch tubes. The test channel had vertical headers and 22 horizontal branch tubes, and the distributing pipe had 21 outlet holes bored at the same pitch as branch tubes. We found that the refrigerant spouted from all holes of the pipe except under the lowest mass flow rate, and the uniformity of liquid distributions to branch tubes was much improved in comparison with the channel without the distributing pipe.

We demonstrate the power enhancement of silicon thermoelectric generator by using phononic crystal nanostructures. In the recent ICT society, thermoelectric devices attract large interest in energy harvester application. We fabricated membrane-based thermoelectric generator on SOI wafer with electron beam lithography and common MEMS process. We measured thermoelectric voltage and output power from temperature difference while heating sample substrate. Phononic crystal nanostructure improves thermoelectric figure of merit twice for poly-Si membrane, and enhances output power 4 times larger in thermoelectric device.

In this study, we tried to measure spectral hemispherical transmittance of piling quartz glass plates with or without double-layer anti-reflection coatings. Overall, the measured spectral transmittance under the conditions of both single plate and 8 plates was consistent with numerical simulation result based on one-dimensional model. However, there was unexpected periodic fluctuation in the wavelength range from 1.5 to 2.0μm. It was shown that the fluctuation proceeded from spectral characteristics of blazed grating for polarized radiation. In addition, the difference between measured and theoretical result in the wavelength region was due to experimental conditions such like use of wave-guide constructed Au mirrors and the quartz glass plates with finite size. As a result, in consideration for the restrictions, it could be regarded that selective transmission of this optical filter for diffuse irradiation was verified in experimental way.

In recent years, with the influence of global warming, high-performance of Double Tube Heat Exchanger constituting car air conditioner is required. As a way to do that, a technique of laying dimples on the inner pipe wall surface of the heat exchanger attracts attention. In this study, numerical analysis was carried out by in-house code for the case where one dimple was laid on the bottom of the rectangular tube to clarify the characteristics of one dimple. As a result, from the viewpoint of the vortex structure in the dimple, teardrop shaped dimple had the best heat transfer characteristics compared to other shapes.

The detailed local flame structure in turbulent combustion has yet to be elucidated. Local flow velocity is necessary to evaluate tangential strain rate relevant to the flame structure. However, because its evaluation method is different in numerical and experimental analysis, it is difficult to compare the results obtained from both analyses and to evaluate their quantitative relationships. In this study, in order to elucidate the detailed flame structure of the turbulent premixed flame, numerical PIV is performed on the DNS data of turbulent premixed flames, and it aims to examine the influence of subpixel interpolation on accuracy of numerical PIV to compare DNS results.

Measurement of electrical resistance, liquid level displacement, and surface observation was applied on ionomer and silica nanoparticle dispersion to clarify the effect of the materials on the proton conductivity. The electrical resistance of the catalyst ink used for fabrication of catalyst layers of polymer electrolyte fuel cells is determined by both electron and proton transport properties. They are affected by the state of the catalyst ink. Therefore, the fundamental understanding of the proton conductivity variation during the drying process of the slurry is important to use the electrical resistance measurement for the sensing tool of the catalyst ink. The measurement showed that silica nanoparticles affect proton transport properties in the slurry when the particle concentration was increased.

A Floating-Zone method is one of the promising method for producing a silicon single crystal. However, this production method has a problem that it is difficult to increase the size of the crystal. The reason is that it is difficult to maintain the crystal shape under the gravity environment. In addition, defect fringes are generated due to the influence of surface tension (Marangoni) convection, which is an obstacle to high purification of the crystal. Therefore, elucidation of Marangoni convection is very important. In this analysis, in order to introduce the analysis method of gas-liquid two-phase flow on Marangoni convection, we conducted research using a more fundamental model.

To characterize the water transport properties in a proton exchange membrane fuel cell electrode, a simple capillary rise experiment is designed to measure the water uptake and to estimate the (external) contact angle to water of carbon-ionomer films. The impact of ionomer content is investigated using carbon-ionomer films with various I/C ratios ranging from 0.8 to 1.4, and the results are compared with the sessile drop measurements. The contact angles measured using the sessile drop method show a slight decrease of the contact angle with the I/C ratio. Because of large uncertainty, however, the contact angle estimated from the capillary rise experiments are unable to capture such a small variation of contact angle for the I/C ratios considered in this work.

In the present study, the combustion flames of pulverized woody biomass in a high-temperature air stream were investigated on the physical properties such as pulverized size and air flow rate, comparing those of fuel gas jet flames. Wood -pellet and pulp and were used for pulverized biomass fuels, and propane was used for gas fuel. The effects of the fuel on the ignition temperature and ignition delay time were examined. It was shown that the decrease of the diameter of pulverized woody biomass reduces the ignition delay time. The results suggest that the ignition characteristics of the pulverized biomass flames are almost the same as those of the gas flames.

Condensation phase change and more specifically dropwise condensation have received important attention in the past decades. Aiming to decrease the contact angle hysteresis between the solid surface and the condensate and hence to increase the droplet shedding performance, slippery lubricant infused porous surfaces (SLIPSs) are being proposed. On SLIPSs, a low surface tension oil impregnates the micro- and/or nano-structured features of a superhydrophobic surface (SHS) reducing the direct interactions between the condensate and the solid surface, which effectively decreases the contact angle hysteresis. As a consequence, SLIPSs can achieve better droplet shedding performance with rolling off angles as low as 5 degrees and 2 times greater heat transfer performance than SHSs . In this work, we investigate the presence and absence of micro-structures underneath the condensing droplets on SLIPSs. Here we report the enhanced shedding performance of hierarchical micro-/nano-structured SLIPSs when compared to one tier nano-rough ones, which will have a strong impact on the heat transfer performance.

In this study, natural convection of a paramagnetic liquid along a vertical heated plate is experimentally investigated in the presence of magnetic fields. Permanent magnet(s) is/are installed behind the heated wall and the local heat transfer along the heated wall is estimated with/without magnetic field. In case of a single magnet, the heat transfer is suppressed near the bottom edge of the magnet and enhanced around magnet top edge under the influence of the buoyancy. This effect also depends on the magnet elevation. By employing multiple magnets, the component of the magnetic force becomes remarkable and the effect is pronounced depending on the number of magnets and the elevations.

To generate electric power from unused heat, realization of heat engines that can work under small temperature difference during the heat exchange processes are required. Trilateral cycle can maximize the exergy recovery from waste heat. The working fluid is maintained in a liquid phase during the heating process and it expands in the expander in gas-liquid two phase. In the present study, a novel reciprocating positive displacement expander for two phase expansion which can achieve large expansion ratio, high airtightness and low vibration is proposed. And issues for practical application is discussed.

The boiling-cooling technology has been gaining attention in the fields of hardening of metals, nuclear reactors or superconducting coils. The boiling phenomena have high heat conductance because they involve latent heat transport due to gas-liquid phase transition. The purpose of this on going study is to elucidate the effects of frost layer covered surface on the boiling cooling transfer. The kind of coating material, the thickness and the surface inclination are important factors in these experiments.

We are currently investigating the boiling heat transfer characteristic in the copper ball of diameter 25mm.

Critical Heat Flux (CHF) under downward flow condition have not been fully understood owing to the complex flow structure caused by the counter force between the buoyancy and inertia force. In this study, the influence of tube diameter and heating length on CHF mechanisms in downward flow have been evaluated. As a result, the effect of tube diameter can be explained by using the dominant force regime map coordinated with Bo, We and Fr numbers. In addition, the comparison results of heating length suggested that CHF mechanisms can be determined by the quality condition at the tube exit under stagnation and co-current region.

Recently, the effect of wettability on boiling heat transfer has attracted a great amount of attention. Due to the difficulties in controlling the wettability of low-surface-tension fluids, there are few studies devoted to liquids other than water. In this research, effective wettability control of ethanol has been achieved by coating the copper boiling surface with a spot pattern of P(FA-C8-coDOPAm) modified halloysite nanotubes which leads to ethanol repellency. Saturated boiling on such a mixed wettability shows over 400% heat transfer enhancement over the uncoated surface. In addition, the maximum heat transfer gains have been to occur around the pitch-to-spot diameter ratio of 2.75.

We focus on the enhancement of boiling performance. Effects of heat transfer surface structures on boiling heat transfer performance are investigated experimentally. We have used five types of heat transfer surfaces (smooth surface and four types of dimple surfaces with different arrangement, pitch and diameter). On the projected area basis, dimple φ1mm (inline; pitch 1.0mm) surface is the best among them, and heat flux of the surface increases about 4.2 times compared with that of smooth surface. Whereas, on the actual surface area basis, φ1mm (inline; pitch 1.5mm) surface is the best, and heat flux of the surface increases about 3.5 times compared with that of smooth surface.

The ice adhesion force to a metal surface has always been measured in a macro-scale, but the measured ice adhesion force is always an apparent value including a force to break the ice. To measure the correct ice adhesion force, one of the authors developed the measurement method in a nano-scale using scanning probe microscope (SPM). And it was clarified the correct ice adhesion force to the copper could be reduced by addition of non-ionic surfactant. In this study, similarly to copper, the surfactant was used, and a glass was used as a test plate. Adsorption characteristics of surfactant molecules to the glass may be quite different from that to the copper. So, ice adhesion forces and the adsorbed amounts of the surfactant were measured by the SPM and QCM, respectively, varying surfactant concentrations. And, validity of the measured ice adhesion forces was clarified based on the adsorbed amounts of the surfactant.

Light-weight and high-performance thermal insulator made of fibrous porous media has been developed. But, when its density is too low, natural convection occurs in it and its performance decreases. In order to reduce weight moreover and suppresses natural convection, inserting high-density layer in a thermal insulator at the middle seems to be promising. However, it is not clear what high-density layer is effective. Therefore, in this study, fluid flow and temperature distribution in a horizontal porous layer with high-density or impermeable layer at the middle were investigated numerically. The porous layer was heated from below and the optimum combination of densities was examined from the viewpoint of weight. The arithmetic expression by the fiber model of Cho et.al. was applied to estimate the permeability of porous layer.

In this study, the flow structure of Marangoni convection generated around a micro-bubble attached to the channel wall by locally heating the wall near the bubble is investigated using numerical method. An axisymmetric vortex flow was generated when the heating area was located at the center of the bubble. On the other hand, when the heating area deviated from the center, a pair of vortices was formed in adjacent to the bubble which matched with the experimental results qualitatively. Further, the effects of the distance between the heating area and the bubble, and the size of the area on the flow structure were evaluated. The results showed that as the heating area size decreases and its position is located closer to the bubble, stronger vortices can be generated.

On the practical micro combustors, fuel cartridge that consists of propane, n-butane and i-butane considered useful as mobile energy source due to its availability and cost. In this study, the effect of fuels species on the micro vortex combustor, which has the world highest output power has been experimentally investigated. Output power and exhaust CO concentration have been investigated, and furthermore, flame observation has been made using visualized combustor made of quartz. Results showed that the output power of miniature vortex combustion system is almost the same for propane, n-butane and i-butane. For all mixtures, large amount of CO tends to emitted when the equivalence ratio was decreased less than 0.85. Flame appearance observed with quartz combustor has revealed that the flame base is weakened for fuel lean condition, which is attributed to the Lewis number effects.

This paper describes feasibility of switchable heat storage device, that can switch the thermophysical properties, using solid-solid phase-change thermal storage materials (PCMs). Solid-solid PCMs have some merits compared to solid-liquid PCMs: high thermal conductivity and unnecessary of container. Therefore, the solid-solid PCMs are suitable for micro scale thermal control device. Vanadium dioxide (VO₂) is one of the solid-solid PCMs. In this study, the electrical resistance of the VO₂ powder was measured under compressive pressure to estimate the phase transition temperature (PTT). As the result, onset PTT and end PTT decreased 2.1°C and 3.5°C under compressive pressure, respectively.

The effects of molding pressure on thermal diffusivity and thermal conductivity of sand mold have been studied. In this work, resin bonded sand molds were formed with three kinds of sand (Espearl, Flattery silica sand, Silica sand) under conditions of molding pressure 0.2～0.4 MPa. Thermal diffusivity and thermal conductivity of these sand molds were estimated by using an inverse solution for one-dimensional unsteady heat conduction. As a result, thermal diffusivity and thermal conductivity of sand mold formed with Espearl were increasing with increasing of molding pressure. Thermal diffusivity and thermal conductivity of sand mold formed under condition of 0.4 MPa were 28 % and 14 % higher than that of 0.2 MPa respectively. On the other hand, thermal properties of sand molds formed with natural sand were decreasing with increasing of molding pressure.