In the subcooled flow boiling, bubble size is important in calculating the vaporization rate accurately. On the surface, a number of bubbles that are different size are generated. If the bubble size is assumed to be uniform, a serious error may be caused in the numerical simulation. In this study, considering bubble size distribution, the bubble size are predicted by the gamma distribution. It was demonstrated that the gamma distribution satisfactorily describes the bubble distribution data. Furthermore, correlations were developed for the dimensionless bubble size and shape parameter to enable accurate prediction of them in the subcooled flow boiling.

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This paper gives prediction to the transient heat transfer at Departure of Nucleate Boiling (DNB) point for subcooled flow boiling. The prediction is carried out by solving the heat conduction equations in cylindrical coordinates with convective boundary condition, which changes with the change of the heat transfer mode on the heated surface. DNB is assumed to happen at the complete dryout of liquid sublayer trapped between the heated wall and an elongated vapor clot, during the passing time of the vapor clot. Important parameters including initial thickness of the liquid sublayer, vapor clot length, vapor clot velocity and void fraction etc., are calculated from the Liu-Nariai model. The initial heater surface temperature is derived from the Jens- Lottes correlation. The transient changes of liquid sublayer thickness, surface temperature at DNB are reported. No obvious temperature jumping is observed at DNB. To predict temperate excursion at Critical Heat Flux (CHF), more simulations to the transient boiling and film boiling processes are needed.

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The present paper aimed to clarify the boiling heat transfer, especially the mechanism of the critical heat flux. Pool boiling experiments were conducted the copper thin film on the silicon wafer by the sputtering. Test liquid was distilled water. The system pressure was 0.01 and 0.10 MPa, respectively. Boiling heat transfer mechanism was examined through two-dimensional temperature field and high speed observations of the boiling bubble. Temperature of the test heater was measured by using a infrared thermometer from a back side of it. The temperature fluctuation on the test heater was considered with bubble behavior.

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The behavior of rewetting on a high superheated and dry surface, focusing on rewetting temperature just as collapse of saturated and subcooled film boiling was investigated experimentally. Saturated and subcooled impingement jet experiments were conducted by using a silver plate with 40.0× 40.0 mm (length × width) and pure water at atmospheric condition. The liquid subcooling was 0, 10, 20, 30, 40, 50 and 75K, respectivelity. Temperature of the test heater was measured by using a commercial separated-type infrared thermometer from a back side of it. The sputtering temperature, i.e., rewetting initiation temperature, was close to the value given by Nishio's correlation, 200℃, in spite of liquid velocity and liquid subcooling.

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In this study, effects of the droplet flow density and mean droplet diameter on film boiling heat transfer and collapse temperature of film boiling (MHF point temperature) of spray nozzle cooling were examined experimentally. A test heater was Nichrome foil with 0.2 mm thickness, 5 mm width and 100 mm length. The droplet flow density was 50, 100 and 200 l/min m^2, respectively. The mean diameter of droplet was 130, 198, 301, 352, 415 and 472μm, respectively. The test heater was heated by DC current through DC power supply. The temperature of test heater was measured by using a K-type thermocouple. The present experimental results showed that film boiling heat transfer increased with increasing mean droplet diameter. The effect of the mean droplet diameter on MHF point temperature was weak. On the other hand, film boiling heat transfer and MHF point temperature increased with increasing droplet flow density. The correlations were obtained for film-boiling heat transfer and MHF-temperature. Large temperature fluctuations near the MHF temperature condition was confirmed.

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Unsteady boiling heat transfer characteristics while water spray cooling were experimentally measured, focusing on effects of surface oxide film on steel plate, in order to obtain fundamental information for improving TMCP in steel production process. Oxide film thickness and its characteristics were measured before and after spray cooling, by laser microscope. Oxide file thickness ranged between 0 to 50 μm. It was found that heat transfer characteristics in film boiling region and MHF conditions were affected by oxide film thickness, liquid subcooling and liquid flow rate density.

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Dropwise condensation(DWC) has high heat transfer coefficient. However, DWC may no maintain long period. In order to maintain DWC long enough, it is important to understand the effect of the surface condition. In the present paper, wettability of metal-sputtered surfaces was controlled by MEMS technology. The effect of several metal-sputtered surfaces, i.e., Cupper(Cu), Titanium(Ti), Silver(Ag) and Chromium(Cr) respectively, and the on the pattern of the condensation, i.e., DWC or FWC, was examined qualitatively. The surface condensation with sputtered thin Silver(Ag) and Chromium(Cr) films were DWC. On the other hand, the surface condensation with sputtered thin Cupper(Cu) and Titanium(Ti) films were FWC. When equivalence contact angle was over 72 degree, DWC was found. The other hand, when the angle was under 62 degree, FWC was observed.

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We study Marangoni dropwise condensation of a binary vapor mixture in the framework of a long-wave model. The average mass and heat fluxes increase with respect to those in the flat-film state. We reveal that the increase of the average mass flux mainly arises from nonlinear coupling of the disturbances of the film thickness and the mass flux. Furthermore, we propose a simple expression for the average mass flux. This model suggests that the rate of the average mass flux to that in the flat-film state becomes larger at smaller ambient vapor concentrations of the lower-boiling-point component, which is consistent with experimental results.

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In summer, prefabricated buildings, warehouses, factories, etc., from the attic side of the building using a steel roof, there are much heat intrusion, room temperature rise has become a problem. As a countermeasure to prevent the intrusion into the room from the past of the roof, such as insulation materials or high solar reflectance paint to paint on the roof surface was mainstream. The heat from the attic surface into the room is generally transferred by convection and radiation. The high solar reflectance coating so as to suppress the heat intrusion by reflecting sunlight. The heat insulating material reduce the heat intrusion by lowering the attic surface temperature. In this study, we verified the mechanism of increased inhibitory effect of heat intrusion and room temperature and WBGT in the summer when you have painted a low emissivity paint in the attic surface of the prefabricated unit house.

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This paper describes the effect of using the low-concentration to the multi-junction solar cell module fabricated by the smart stacking technology. In this module, a high-efficiency cell (e.g. III-V MJ cell) is mechanically stacked on a larger-sized low-cost cell (e.g. Si or CIGS cell); the current matching between the stacked cells is managed by the area ratio of the cells and the irradiance distribution controlled by the concentrator. Simulation and experimental result shows that the control of irradiance distribution assists the current matching of the cells and reduces the top cell size without decreasing the module efficiency, resulting in higher efficiency and lower cost.

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For precise thermal control in satellites under varying internal heat dissipation and thermal boundary condition, we propose a high-fill factor MEMS radiator enhanced by near-field effect. In the present design, polymer springs are shared among adjacent diaphragms, and its structural parameters are decided based on analyses of its resonance frequency, driving voltage, and heat flux ratio. We have successfully fabricated our prototype and its fill factor is significantly improved as high as 89 %. The surface temperature on the diaphragm is measured with infrared thermal imager, and is increased from 67.4 ℃ to 77.9 ℃.

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Technologies for drying a material with a flammable solvent at a low temperature are required. It is reasonable to evaporate a flammable solvent using radiation at the absorption band of a flammable solvent and to eject the flammable vapor with a cold air. The meta material with Au/Al2O3/Au was fabricated by using an sputtering equipment, an atomic layer deposition equipment, and an electron beam lithography equipment. The reflectances of the meta material structure were measured by using an FT-IR equipment with an integral sphere. It is clarified that the emissivities of the meta material structure are larger than 0.8 at the absorption band of toluene.

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We have fabricated metal-insulator-metal (MIM) structures, which is so-called plasmonic perfect absorber. For high temperature application, molybdenum which is a refractory metal and aluminum oxide were used as the metal layer and the insulator layer, respectively. The top Mo layer is composed of disk array structure, obtained by means of colloidal lithography and reactive ion etching. The absorption peak of the structure was narrow-band and could be successfully tuned in the mid-infrared range. The emission properties at high temperature were also evaluated. The MIM structures showed good thermal stability at high temperature up to 800℃ and thus can act as a high temperature wavelength-selective thermal emitter.

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We investigated the spectral emittance of a gold-coated micro-particle array. We measured the spectral normal emittance of the samples. The diameter of micro-particles is 5 mm. We changed the number of layers of micro-particles. From the measurement result, enhancement of emittance has been checked at the wavelength of 5 mm. This enhancement of emittance depends on structural period. This characteristic enhancement of emittance was checked at the wavelength of 9 mm in all of the samples with different number of layers. Therefore, we consider this enhancement of emittance is independent of the number of layers.

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Raspet et al. derived propagation equation for a wet-walled regenerator. They found that in comparison to a thermoacoustic heat engine with a dry regenerator, the critical temperature at which self-induced oscillation occurs is lower and the acoustic power amplification is higher in a thermoacoustic heat engine using a wet regenerator. However, the acoustic power amplification of a wet regenerator has yet to be experimentally verified. In this study, we measured the acoustic power amplification gain of a wet regenerator and compared it with that of dry regenerator. This result indicates that an acoustic power amplification exceeding the temperature ratio is possible when using a wet regenerator, though gain essentially does not exceed the temperature ratio in a dry case.

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In this study, experimental study on thermoacoustic device which has three different thickness of stacks made by SLS manufacturing has been investigated. The thermoacoustic devices have two different length of its resonance tubes, and temperature difference between stack has been measured by thermocouples. As a result, for each tube, temperature difference was periodically and in reversely observed according to the sound frequency. The maximum temperature difference was observed in the frequency corresponding to the resonance frequency of each tube. The largest temperature difference was observed with stack height of 36mm in these experiments. Large temperature difference was also observed as the applied voltage is large. From the experiments, it was revealed that a large temperature difference is observed at a specific frequency with thick stack and high applied voltage.

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Low-grade Thermal Energy Conversion (LTEC) utilizes the unutilized heat source and a small temperature difference between high- and low-temperature heat sources. Therefore it is necessary to enhance the thermal efficiency of the LTEC system and then a multi-stage cycle is proposed. This paper investigates on the influence of the temperature difference between high- and low-temperature heat sources on the system performance of the double-stage Rankine cycle. Calculation results show that the temperature difference has no influence on the maximum power efficiency and the ratio of the heat source temperature change to the optimal temperature change.

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Low-grade Thermal Energy Conversion (LTEC) is a heat engine to convert the thermal energy into the electricity. LTEC plants use unutilized low-grade thermal energies as heat sources such as seawater gradients, hot spring and exhaust heat from industrial plants. The evaluation parameter is significantly important for the suitable design of the power plant. This paper describes about relationship between exergy of heat source and power output of a cycle. It's reviled that the difference of characteristic between exergy of heat engine and power output of cycle. As a result, the power output efficiency is suitable for the evaluation of the LTEC power plant systems rather than exergy efficiency because the maximum power output efficiency shows maximum power from the systems.

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This paper studies heat transfer on counter-flow heat exchangers. An analytical study was conducted using a simple model. The model consists of two fluids with high temperature gas and low temperature water whose flow directions are opposite. Two fluids are separated with a stainless steel material. Delta wings were used as vortex generators and the gas flow was optimized from the standpoints of configurations and arrangements of the delta wing. As a result, it was found that the longitudinal vortex system generated by delta wings has a key role in achieving high performance of heat transfer.

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An exhaust heat recovery system using exhaust gas discharged from the factory is effective method for the energy problem. However, particles which deposited in the duct of the exhaust heat recovery system decrease heat transfer because these exhaust gas contains many fine particles. The purpose of this research is assessment of dust deposition in the exhaust heat recovery system. As an effective method, the flow field, temperature distribution and particles deposition height in the duct are analyzed by CFD. In this paper, the analytical results which was placed rectangular plate in the duct are shown.

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In the present study, a model to predict adiabatic efficiency and phase change in two-phase adiabatic expansion is proposed. Experiment of reciprocating expander is carried out to obtain basic experimental data such as pressure variation and adiabatic efficiency. Phase change inside an adiabatic cylinder is modeled, and experimental correlation for the Nusselt number based on Prandtl, Reynolds and Bond numbers is proposed. Using the proposed correlation, pressure change and adiabatic efficiency can be calculated. It is confirmed that the model predictions of the pressure change and adiabatic efficiency match well with the experimental results.

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Fuel components with a high octane number and rapid flame speed, which are generated through fuel reforming using exhaust heat, improve the thermal efficiency of spark ignition engines owing to the stabilization of a high EGR (exhaust gas recirculation) combustion. In this study, we estimated the reformed fuel components of gasoline and the energy recovery ratio through an equilibrium calculation using a detailed chemical kinetic model of a gasoline surrogate under exhaust gas conditions when the gasoline engine was operated under an excess air ratio of 1.0 at an EGR rate of 1-27%. We also calculated the flame speed of the premixed gas including the reformed fuel components. We found that the energy recovery ratio exceeded 1.0 over the entire EGR rate and that the increasing ratio of the flame speed increased with an increasing EGR rate under an excess air ratio of 1.0.

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Heterogeneous nucleation of liquid droplets on a solid surface with and without the nanostructures is directly simulated by the classical molecular dynamics simulations and the effects of morphology of the nanostructures, on the nucleation rate, are investigated. The potential energy between the fluid molecule and solid atom is assumed to be the 12-6 Lennard-Jones form, and the energy scale parameter is changed to reproduce various degrees of wettability. The results showed that in the case of a solid surface without nanostructures, as the wettability of a solid surface becomes better, the nucleation rate becomes higher. On the other hand, when there are nanostructures on a solid surface, the influences of morphology of the nanostructures, on the nucleation rate, depends on the wettability of a solid surface and the nanostructures.

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It is known that the thermal resistance at a solid-liquid interface is changeable when nanoparticles adhere to a heat transfer surface. This is partially because the liquid density around nanoparticles is changed by the nanoparticle-liquid interaction. In the present study, we conducted nonequilibrium molecular dynamics simulations and investigated the effects of the intensity of nanoparticle-liquid interaction and liquid pressure condition on the liquid density profile and the thermal resistance at the solid-liquid interface. The result shows that the thermal resistance at the solid-liquid interface does not so strongly depend on the pressure condition when the change in the pressure does not influence the liquid density in the nanoparticle layer.

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Molecular dynamics simulations are conducted to investigate an influence of nanometer scale slit structures on molecular adsorption to a solid surface. Also, we investigate an effect of the molecular adsorption on the accommodation coefficient at a solid-vapor interface by changing interaction potential parameters between solid and fluid, clearance and height of the structures. Our simulation results show that, both an adsorption amount and the momentum accommodation coefficient (MAC) vary depending on the slit structure geometry and an intensity of the interaction potential parameter between the solid and the fluid. Moreover, it is found that there is a positive correlation between the adsorption amount and the MAC.

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The molecular level mechanism of thermal energy transfer is important in thermal engineering or understanding the factors that determine macroscopic thermal conductivity, which enables design of thermal medium having desired thermophysical properties. This is a report of non-equilibrium molecular dynamics (MD)simulation of heat conduction in ionic liquids, which attract attentions in various engineering fieldsrecently. MD simulations were performed for 1-butyl-3-metyhlimidazolium ionic liquids at 323 K and 1×10^5 Pa by using the united atom model in three systems which have different size of anions (F^-, Cl^- and Br^-). Thecontributions of molecular migration and intra/intermolecular interactions to heat flux has been analyzed.

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The stability of the clathrate hydrates are closely linked with the guest-host interactions in the cages. The equilibrium condition of the clathrate hydrates enclosing fluoromethane molecules are depending on the number of fluorine atoms in the molecules. However the mechanism of the changes of the phase equilibrium condition is still unclear. In this study ab initio molecular dynamics simulation were performed on the fluoromethane clathrate hydrates and analyzed the distributions of the guest molecules in the cages. The effects of the differences of the molecular motions on the stability of the hydrate cages are indicated.

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In this study, we carried out a dissipative particle dynamics simulation about two kind of the length liquid crystal molecules. In this simulation, we observed phases as a volume fraction of liquid crystal molecules as a parameter with temperature change. As a result, we found that a transition temperature from isotropic phase to nematic phase depends on the volume fraction.

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A polymer droplet is droplet constructed by polymer chains. The polymer droplet has the great possibility of the application in the industry. However, detailed structure of the polymer droplet have not been yet elucidated under various conditions. In this paper, to investigate behaviors of polymer droplet, we adopted the Many-body Dissipative Particle Dynamics (MDPD) simulation. We measured the radius of droplet and the contact angle, and examined the size effect of polymer droplet system. !

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A Janus nanoparticle is a unique anisotropic nanoparticle which typically has two or more distinct surfaces, each with different properties. In the present study, we performed molecular simulations to investigate the morphologies and phase diagrams of self-assembled diblock and triblock Janus nanoparticles confined in nanotubes. We derived qualitative phase diagrams of the the axial pressure versus the ratio of the nanoparticle diameter to that of the nanotube. Two distinct types of nanotube wall, namely hydrophobic and hydrophilic, were considered. Moreover, we applied a shear flow to hydrophobic/hydrophilic these structure and observed change of structure.

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This research discusses the fundamental liquid flow characteristics in carbon nanotubes (CNTs). The liquid argon flows through CNTs of (6,6)-(160,160) at T=121[K] and ρ_b=1344.3[kg/m^3] are simulated by themolecular dynamics (MD) method. To fit the velocity plot points obtained by the MD, the momentum equation is considered and solved by the finite difference method using the simulated density distributions. The theoretically reasonable velocity fitting lines are given. Using these velocity profiles, it is found that the slip length and the flow rate enhancement have obvious three transitional ranges, between (6,6)-(8,8), (9,9)-(10,10) and (14,14)-(17,17) before flow characteristics converge to the bulk flow ones.

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In this study, we have evaluated the force around the contact line by Molecular Dynamics Simulation. Using nine different-sized nano channel, we evaluated the channel size dependence of the friction force around the contact line region by one component of the stress tensor. Compared with the force evaluated by dynamic contact angles, we can say that in the case that the channel size is smaller than 10 nm, the friction forces evaluated by the shear stress do not agree with the force by the dynamic contact angles.

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Growth rate of titanium nitride (TiN) film by thermal chemical vapor deposition (CVD) in horizontal tubular reactor was investigated experimentally for various setting temperature, total gas flow rate and diameter size of the tubular reactor. There were two regions for the growth rate distribution along the axis in the tubular reactor. In the first region, the growth rate could be controlled by the gas phase reaction of TiCl_4. On the other hand, in the second region, the growth rate was found to decrease exponentially with axial position in the reactor and could be controlled by the diffusion rate of TiCl_4.

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Electrodialysis using ion-exchange membranes is a means of producing dilute and condensate under the influence of an applied electric potential difference of saltwater. In this study, we have investigated the transport process of ions in the electrodialysis stack under the influence of an applied electric field. Under a limiting current density, the ion concentration totally vanishes at the exit of the diluate channel so that the electric resistance goes infinity toward the diluate side of the cation exchange membrane, which is referred to as concentration polarization. The effect of the flow field on this limiting current density, which is one of the most important design parameters in the electrodialysis stacks, have been investigated by measurement of the electric resistance and concentration.

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The objective of this research is to investigate the possibility of producing phenol directly from a mixture of toluene and water by in-liquid plasma and to understand the process of converting toluene into phenol. Radio frequency (RF) in-liquid plasma was used to synthesize phenol from toluene. In addition, GAUSSIAN was used to predict the process of conversion and other products. In the proposed method of phenol production, OH radicals produced from water molecules by in-liquid plasma play a major role during the process of direct chemical reaction with toluene. The experimental results showed that phenol can be directly produced from toluene, and benzyl alcohol and formaldehyde were synthesized in the process.

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Horizontal temperature distribution on a heated disc set in cylindrical flow channel has been measured to understand heat transfer in a reactor of chemical vapor deposition (CVD). The amplitude of the temperature at middle region of the heated disc was largest because the stagnant point of some vortexes by natural convection could become unstable due to mixing with the forced convection of air supply. The difference of the heat flux between at the center of the disc and at the edge of the disc for the domination by natural convection was much higher than that for the domination by forced convection.

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Flame propagation of coal dust in a combustion tube was carried out through the numerical simulation of two-dimensional unsteady Navier-Stokes equations. In order to deal with the dust-flow interaction, particle in cell method was employed. The chemical reaction of volatile gas was assumed to be reversible 5-step reactions. The chemical species are CH_4, O_2, N_2, CO_2, H_2O, CO and H_2. The simulation reproduces the flame propagation behavior, and the results are agreed with experimental results. Numerical results showed that the flame propagated slowly during the initial stage after ignition. Subsequently, flame propagated more quickly, as the volatile matter burned immediately. It is also verified that coal devolatilization and the combustion of volatile gas significantly affected the flame propagation behavior.

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Vapor explosion is one of the explosion phenomena, which may occur in many industrial fields. In many previous studies, a single metal and water were used as the high-temperature liquid and low-temperature liquid, respectively. However, there are few reports related to the experiments using high-temperature liquid with chloride. Thus, our present focus is on the vapor explosion using high-temperature liquid with chloride. The vapor explosion behavior and pressure were obtained simultaneously. The experimental results were evaluated on the temperature map, the so-called Thermal-Interaction Zone (TIZ). From the evaluation, it is confirmed that the vapor explosion was prone to occur when using the metal with chloride, while the explosion did not occur when using only the metal in the same temperature condition.

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When an accidental gas explosion occurs in an open space, a spherical flame outwardly propagates from the ignition point. The damage caused by the explosion depends strongly on the speed of the spherically expanding flame. In previous studies, empirical (or semi-empirical) models were proposed to estimate the flame speed. The goal of this study is to establish a theory that can predict flame speed without requiring empirical parameters. By reviewing previous theoretical studies, the critical flame radius at which flame acceleration initiates is identified as the key parameter, and it should be theoretically predicted to achieve the goal. In this paper, the linear stability theory developed by Zel'dovich et al. is compared with experimental data. The model prediction that the critical Peclet number is proportional to the Markstein number agrees qualitatively with previous experimental data. However, the theoretically predicted critical radius at which the perturbation amplitude increases more rapidly than the flame speed is smaller than the experimentally observed critical radius at which flame acceleration initiates, requiring further study.

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This paper visualizes explosions in a subsurface magazine model constructed underground to mitigate the effects of blast waves. Numerical simulations discuss the effect of water that is put inside the magazine model. The simulation data shows that the peak overpressures on the ground agree with those in the previous experiment. The increases of kinetic and internal energies of water are then estimated, and that the heat transfer at the interface of water and air is a dominant factor to mitigate the blast wave on the ground.

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This paper deals with a self-ignition mechanism of high-pressure hydrogen jet in a tube filled with air. Although the self-ignition phenomenon is expected to clarify for industrial safety, the ignition mechanism in a tube still has not been known well. In this study, the direct photographs of flame behaver initiated by the self-ignition are captured by a high speed camera. The flame propagation histories are obtained from the pressure and light sensors. Additionally, a numerical simulation is performed to understand the ignition process induced by hydrogen jet in detail. As the results, a self-ignition occurs at the region where the contact surface interacts with the local high-temperature region which is built by the shock wave reflects from the sidewall of tube.

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We have experimentally investigated thermal fields in the near-field of a medium-size ethanol pool fire under confined ventilation conditions, which was generated in a compartment poorly ventilated by a mechanical system with a merger negative pressure. Special attention was paid to the impacts of the changes in organized motions (from puffing to meandering motions) with transition to ventilation controlled fire, which has been revealed with our previous studies. The temperature fluctuations measured with fine thermo-couples shows that the meandering motions yield the increase in temperature fluctuations in low frequency region which is smaller than that with puffing motion just above the center of pool.

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In the simulation of fire whirl, the effect of the turbulent viscosity model in LES of FDS (Fire Dynamics Simulator) is investigated. The latest FDS version 6 employs five kinds of the turbulence viscosity model; (a) Constant coefficient Smagorinsky model, (b) Dynamic Smagorinsky model, (c) Deardorff model, (d) Vreman's eddy viscosity model, (e) Renormalization group eddy viscosity model. All of these models are tested, and then clear influence of the model does not appear in fire whirls at this calculation conditions. However, the influence in a flow field at the downstream of the L-shaped fire source is observed. This has been suggested that there is a need for caution in predicting the spread of fire.

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In order to clarify the characteristics and mechanism of rubber balloon extinguishment, the extinguishing experiments have been performed. The extinguishing target was a methane-air diffusion flame formed over a porous burner. Physically-acting inert gases were used. In this study, extinguishing probabilities have been measured by varying the volume of the inert gas filling into the rubber balloon and the methane flow rate which changes the heat release rate of the flame. From the experimented result, we have revealed the extinguishing limit, which means the minimum inert gas volume required for achieving flame extinguishment.

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Extinguishment experiments of a methane-air diffusion flame have been performed by using water vapor, which was produced due to impacting of a water droplet onto a heated wall. The water droplet diameter was 3.0 mm. The temperature of the heated plate was varied from 100℃ to 430℃ and the extinguishing probability were measured. The behavior of the water vapor produced on the heated wall was visualized with metal halide ramp and recorded with digital camera. From the experimental results, we have discussed about the relationship between the extinguishing probability and amount of the generated water vapor.

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Tests with flames spreading over wires in microgravity were performed at external opposed flow and concurrent flow conditions to examine the influence of flow direction on the extinction limit. In the experiments, low density polyethylene insulated Nickel-chrome and Copper wire samples were used. The experiments were conducted both in normal gravity and microgravity. Limiting Oxygen concentration (LOC) of microgravity is lower than that of normal gravity because of inhibited natural convection. LOC of Nickel-chrome is lower than that of Copper because of difference of heat conduction loss. The minimum LOC of concurrent flow is smaller than that of opposed flow in the range of 1-2%.

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Extinction characteristics of both diffusion and premixed hydrocarbon (CH_4, C_3H_8, and DME) flames at elevated pressures were studied using counter flow configuration. Experiments were conducted under N_2 dilution and CO_2 dilution conditions. For all fuels, flames were found to become hard to be extinguished either with increasing pressure or using CO_2 dilution in place of N_2 dilution with keeping the same adiabatic flame temperature. The effect of pressure on extinction characteristics was quantitatively discussed in terms of Damkohler number using numerical simulation.

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Although conventional flammability tests for solid materials such as NASA STD-6001B or JIS K 7021 are conducted in normal gravity condition, many researchers have reported that the flammability of a solid material extends in a mild flow which is slower than the buoyant flow. In the present paper, we conduct scale analysis for a thermally thin flat material with an opposed flow, and propose a method for predicting the minimum limiting oxygen concentration of the material in microgravity environment with using the data obtained by downward spread test conducted in normal gravity condition.

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The total radiative heat flux and the radiation spectra of the ammonia flame were measured to understand the radiative characteristics of ammonia flame in this study. A slot burner was used for stabilizing the laminar ammonia/N_2/O_2 premixed flame. The concentration of O_2 in the oxidizer and equivalence ratio were varied for increasing the flame temperature. The results showed that radiative heat flux of ammonia was lower than that of methane/air premixed flame in all condition of that has the same net heating values per unit time.

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Recently, CO_2 emitted by motor vehicles are getting worse the global warming. Therefore, a lot of studies are being conducted all over the world for developing the FCV(Fuel Cell Vehicle). In this study, we focus on an effect of a tank shape on a temperature of hydrogen in a tank during refueling of hydrogen. Thence, we clarified how the ratio of volume to surface area in a vessel contributes the temperature rise in the hydrogen in a tank during filling of hydrogen based a proposed refueling model which is commonly accepted to build SAE protocol.

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