To reduce victims, a ventilation system has important role at tunnel fire. In this study, thermal flow behavior is numerically predicted in several ventilation wind velocity at one-way tunnel fire. Fire Dynamics Simulator (FDS) is employed for this study. Heat release source is put as a box on the center in tunnel. Heat release rate and box size are given at several conditions as a car, bus and so on. The numerical results show hot gas flows downward when a ventilation wind is fast. Hot gas, however, goes upward along a ceiling, when a ventilation velocity is slowed down. The critical ventilation wind velocity with each condition is estimated.

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This study is performed to examine experimental the burning velocity characteristics of the methane-premixed micro-scale spherical laminar flames with the flame radius r_f < approximately 5mm, and also macro-scale laminar flames with r_f > 5mm for comparison. The mixtures have nearly the same laminar burning velocity and different equivalence ratio φ(0.8〜1.0). The radius and the burning velocity of micro-scale flames are obtained by using sequential schlieren images recorded under appropriate ignition conditions. The results show that the burning velocity of methane-premixed micro-scale flames has tendency to increase with increasing r_f and approach that of macro-scale flames.

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Recently, micro-combustors which combust hydrocarbon fuels at micro scale are expected to be applied for heating, generating electronic power, and so on. In general, it is difficult to combust premixed gas in a narrow space. The combustor size becomes smaller, the ratio of heat loss to heat input becomes larger, and combustion becomes more unstable. However, micro-combustors use burnt gas enthalpy to stabilize combustion. This research used quartz glass tube with relatively small inner diameter as a combustor. External heating of the tube was made by a Bunsen burner or by covering it with another quartz glass tube with or without steel wool in which the burnt gas flew. We investigated flame stabilization condition and flame velocity inside the narrow tube.

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To investigate propagation of methane-air premixed flame in constant volume vessel, constant volume combustion chamber which can control turbulent characteristic and is applied by optical measurement has been developed and time-resolved measurements of CH chemiluminescence have been conducted. When flame front approaches near wall region, CH chemiluminescence vanishes and flame quenching occurs. Distance between flame front and wall when flame quenching occurs (quenching distance) is smaller in stoicheiometric condition than lean condition. Displacement speed of flame front above the ignition point decreases gradually as flame front approaches the wall, and corresponds to laminar burning velocity approximately just before flame quenching.

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Direct numerical simulations of turbulent premixed flame in confined vessel have been conducted to investigate heat losses and quenching mechanism of turbulent premixed flames near the wall. Near-wall behaviors of hydrogen/air premixed flames and heat transfer characteristic were investigated by considering detailed kinetic mechanism and temperature dependence of transport and thermal properties. In confined vessel, the frame is affected by the pressure wave which caused by the flame ignition and the flame propagation, and the flame displacement speed of the appearance decreases remarkably. However, the turbulent burning velocity at that time doesn't decrease because of an increase of fluid velocity normal to the flame.

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Three-dimensional direct numerical simulations (DNS) with detailed kinetic mechanism have been conducted for statistically-planar, freely-propagating turbulent flame and turbulent V-flame of hydrogen-air mixture in relatively high Reynolds number turbulence. DNS of each configuration was performed in two numerical conditions which are characterized by the difference of Reynolds number. From these results, eigen values of strain tensor are evaluated to investigate characteristics of the strain field near the flame and alignment of the principal strain and flame. Strong dependency of turbulent-flame interaction on Reynolds number and convection are revealed. Interesting feature of high Reynolds number turbulent flame is described as well.

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Three-dimensional direct numerical simulation (DNS) of methane-air turbulent premixed flame with a realistic reduced kinetic mechanism has conducted to investigate effects of turbulence characteristics on the local heat release rate. Numerical condition of the DNS is classified into thin reaction zones of combustion diagram proposed by Peters. Quite low heat release rate regions corresponding to the local extinction are observed. In the vicinities of these regions, flame elements are strongly stretching into two tangential directions. The local extinction mechanism was clarified by introducing life time of reactive species relative to strong coherent fine scale eddies in turbulence.

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Turbulent burning velocity of spherically propagating flame kept increasing with flame propagation. The range of scale of turbulent eddy effective to the turbulent burning velocity might be changing during the flame propagation. Small flame kernel is wrinkled only by the small scales of turbulence. As the kernel continues to grow, it becomes progressively wrinkled by the larger length scales of turbulence. The turbulence that affects to flame kernel effectively was called "effective turbulence intensity" in this study. Energy spectrum of turbulence was obtained from PIV measurements. Effective turbulence intensity was evaluated quantitatively from energy spectrum of turbulence. Then relationship between turbulent burning velocity and effective turbulence intensity were investigated.

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The eddy dissipation model (EDM) can be used with RANS model. However, a typical EDM uses only the time scale of RANS model as the time scale of reaction. Therefore, an EDM cannot be applied for the wrinkled flame in premixed flame. For example, the laminar burning velocity affects the turbulent burning velocity. Proposed in this paper is an EDM which includes the laminar burning velocity. When turbulence strength is high, time scale of the new model approaches that of the original EDM. When the turbulence strength is low on the other hand, flame described by the new model propagates with the laminar burning velocity.

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For technological development of applicable burning analysis to product development, we developed an eddy dissipation model including laminar burning velocity and build this new combustion model into universal thermo-fluid analysis software (Software Cradle products: SCRYU/Tetra V7). In this paper, we conducted accuracy validation of this combustion model. As a result, the calculation of high temperature case was comparatively consistent with experiment data.

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The mechanism of burning rate enhancement for a single droplet flame in varying forced convection at high pressure previously found in our microgravity experiments was numerically investigated. The excellent agreement on the unsteady behavior of droplet combustion between experimental results and numerical ones were obtained. It was shown that a toroidal vortex formed downstream of the droplet at high pressure pushes back the flame in the wake region and heats the droplet, and thus enlarges evaporation rate of the droplet, as well as in the stagnation region upstream of the droplet.

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This paper describes a mathematical model to calculate a mass of generated water vapor at micro-explosion by using the mass and energy conservation equations under some assumptions. To develop the mathematical model, single droplet experiment was carried out. A W/O emulsified fuel droplet suspended by thermocouple was heated by halogen spot heater, and micro-explosion was observed with high-speed video camera. During heating of droplet, the progress of the coalescence of dispersed water droplet was observed. The calculated mass of water vapor generated at micro-explosion was compared with mass of aggregated water droplet just before micro-explosion. As a result, the validity of the proposed model of micro-explosion was shown, and it was revealed that almost whole water droplet was changed to vapor at micro-explosion instantaneously.

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The objective of this research is to investigate the melting and the burning characteristics of polyethylene film in microgravity field. This experiment was conducted using Drop Experiment Facility in Micro-gravity Laboratory of Japan. The flame and the droplet became spherical shape in micro gravity field. For 850K and 900K temperature in the furnace, the droplet diameter first increased and then decreased due to occurrence of expansion and vaporization before polyethylene film ignited. After ignition, droplet diameter suddenly increased, and then decreased. For the 950K temperature in the furnace, the droplet diameter increased gradually until polyethylene film ignited. After ignition, droplet diameter, d, suddenly increased, and then d^2 decreased lineally, showing d^2 low.

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An experimental study has been carried out on the synthesis of carbon nanomaterials using Ni catalyst in methane / air laminar, fuel-rich premixed flames under atmospheric pressure. By placing a pair of porous media in the upstream and downstream sides of the combustion space, excess enthalpy burning was applied to the methane / air mixture. We have investigated effect of reaction time on nanomaterials growth. As a result, it has been clarified that carbon nanomaterials with a diameter of from 20 to 50 nm are synthesized in the downstream side of the exothermic reaction zone.

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Y_2O_3: Yb, Er nanophosphors were prepared using a methane/oxygen diffusion flame at low pressure with vapor precursors and those prepared nanophosphors were examined by TEM, XRD, and fluorescence spectroscopy. The crystalline structure of prepared nanophosphors depended on only the flame temperature, although the size of nanophosphors depened on both the flame temperature and the gas pressure. The photoluminescence characteristics were affected by the crystalline structure which could be controlled by only the flame temperature.

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The shrinking process of the packed layer has been investigated. Filmy plastic and woody biomass are selected as the packing material. The volume of the layer reduces with time and then approaches an equilibrium value. For filmy mixed plastic layer, the shrinking rate constant can be estimated by the non-liner combination of the component of the pure plastic. On the other hand, for the woody biomass, the shrinking rate constant varies dramatically with the component of the lignin. It is found that the shrinking process of the plastic layer can be expressed by the similar analysis of first-order chemical reaction with the equilibrium in this study.

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Bio-coke, one of biomass fuels, is expected as a substitution to fossil fuel to prevent global warming as well as the other biomass energy. In this study, we investigate combustion characteristics of bio-coke in high temperature airflow, especially for ignition processes, which is not widely-known. Japanese knotweed is chosen as an ingredient of bio-coke. The gas temperature near the sample is measured by thermo-couple, the surface temperature of bio-coke is monitored by IR camera and the reduction of weight is scaled by a balance. It is identified that there are two types of ignition mode depending on the air temperature supplied.

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Presently, recycling and disposal of organic wastes need a large amount of labor and energy due to such problems as the dioxin emission. Therefore, it is thought that to develop a new pyrolysis mechanism for organic wastes contribute to solving the environmental problem. Consequently, we suggest a safety and inexpensive pyrolysis mechanism in which incomplete combustion occurs in small area on ceramics bed (thin burning layer) because ceramics are well thermostability and have good thermal radiation characteristics at high temperature. Organic compounds pyrolyze in the thin burning layer only.

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Process of biodiesel fuel (BDF) production from microalgae desmodesmus is analyzed from the view point of energy consumption and CO_2 emission. The process consists of filtration, drying, extraction, and esterification. Because filtration deals with huge amount of water comparing with the weight of harvested microalgae, improvement of efficiency in this process is mandatory for total system efficiency. To reduce the energy consumption and CO_2 emission during the drying and esterification processes, it is also important to develop new single process to synthesis directly BDF from wet algae.

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Experimental study has been conducted to produce the carbon dioxide hydrate in emulsions for improving a fluidity of the hydrate slurry. Water in oil emulsions composed of dimethyl silicon oil and purified water doped with a small amount of surfactant were prepared by briskly mixing of homogenizer. Carbon dioxide absorption and hydrate production experiment was carried out for various water content and surfactant conditions at 275K under 3.0MPa. The results show that the carbon dioxide hydrate in fine water droplet dispersed in silicone oil was successfully produced. Effect of water content and surfactant solvent in silicone oil was also revealed.

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Gas hydrates such as hydrogen and carbon dioxide can be produced in more moderate condition with tetra n-butyl ammonium fluoride (TBAF). But few reliable data such as the crystal growth rate and the induction time of TBAF semi-clathrate has been obtained. Therefore, in order to measure and estimate the crystal growth rate and an effect of supercooling on it of TBAF semi-clathrate, the temperature increase and its rate were measured in bulk scale. The crystal growth rate in a small channel was directly observed using a microscope. In addition, the effect of sodium dodecyl sulfate (SDS), a kind of surfactants, was investigated.

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In this study, flow and heat transfer characteristics of Tetra-n-butyl ammonium bromide (TBAB) hydrate slurry in horizontal pipes were investigated experimentally, and the pressure drop and coefficient of heat transfer were measured. Then, the initial concentration, solid fraction and Reynolds number were varied as the parameters. The results of measurement were arranged using the non-dimensional parameters, such as the coefficient of pipe friction and Nusselt number. As a result, in the laminar flow condition, it was seen that the coefficient of pipe friction and Nusselt number increase with an increase in the solid fraction. On the other hand, in the turbulent flow condition, coefficient of pipe friction and Nusselt number were similar to the values without solid phase in low solid fraction.

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Recently, the difference of power consumption during daytime and nighttime becomes a problem from the viewpoint the environmental protection. There is a latent heat storage system for the one of the solution of this problem. In this experiment, phase change microcapsule as a heat storage material was used. The purpose of this study is to investigate the effect of experimental on parameters heat transfer characteristic of latent heat microcapsule slurry in a curved pipe. It was clarified the effect of experimental parameters such as fluid velocity, curvature radius, microcapsule concentration and heat flux.

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This paper presents the effect of some factors on the flow and heat transfer characteristic of ice slurry in a coil. The ice slurry is solid-liquid fluid which consists of ice particles and water. The experiments were carried out under various parameters of ice slurry velocity, ice packing factor of ice slurry, and heat flux. As a result, it was found that interaction between latent heat of ice and restraint of secondary flow has an effect on the flow and heat transfer characteristic of ice slurry in a coil.

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In this paper we report about experimentally-observed ice-layer growth rates when the rectangular vessel is filled with water and cooled from the top, where the five other walls are all insulated. The initial water temperatures are varied from 4℃ to 50℃. Vigorous convection and the rapid cooling of water body are observed when the initial temperature is greater than 30℃. Elapsed times for the ice-layer to grow to 25 mm in thickness increase linearly with the initial temperature. However, they become nearly constant, and independent from the initial temperatures, when the initial temperatures are over 30℃.

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The purpose of this study is the development of the latent heat storage system using erythritol as a latent heat storage material. In this study, the direct contact melting and solidification behaviors of erythritol were visualized in order to investigate the heat storage and release characteristics of erythritol. The experimental results show that the melting and solidification characteristics of erythritol were influenced with the heating medium (oil) temperature and velocity. And the heat release speed influenced flowing quantity of oil and height of erythritol, there may be a limit in high-speed heat release experiment.

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There is growing interest in the newly developed technology to store heat energy at the temperature of 200 degrees Celsius or lower from industrial plants, which has until now been dissipated. And also, it is important to utilize such waste effectively in order to save energy. A new thermal energy storage/retrieval system, which employs erithritol as heat storage medium and direct contact heat transfer technology as the method for the heat exchange between the heat medium and heat storage material, has been developed. In this system, it is important to evaluate and prove a heat output from the heat storage device. For instance, the performance to maintain heat output high will lead to good economical efficiency. In this study, in order to increase the heat output, tow types of the heat storage device, conventional and improvement type, were manufactured and compared the performance with each other. As a result, improvement type of device which include metal separate plate in the thermal storage media layer have a advantage of increasing heat output.

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Frost adhesion to a cooling surface causes many serious accidents accompanying economic losses. Therefore, it is necessary to clarify the mechanism of frost adhesion to the cooling surface both scientifically and technologically. Considering the size of frost, investigation in micro scale field is essential. However, there has been no the investigation. Thus, in this paper, a scanning probe microscope (SPM) with different radii of the probe attached to the cantilever was used, and the methods to measure frost shape such as the diameter and height and adhesion force of forest to the cooling surface and their effectiveness were investigated, varying humidity and cooling time.

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Ice adhesion to a cooling solid surface often occurs in many situations. And it causes many serious problems accompanying economic losses. Therefore, it is necessary to clarify the mechanism of ice adhesion to the cooling surface. In the past studies, ice adhesion force was affected by behavior of removal of ice from the surface of the cooling plate. Moreover, the force is also affected by surface modification such as plasma and ultraviolet rays irradiation to the plate surface and removal of the oxide layer from the plate surface. Thus, in this paper, considering shear stress corresponding to adhesion force, the relationship between behavior of removal of ice from the copper plate surface and surface modification is investigated with variation in the surface temperatures.

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Frost formation is a transient phenomenon in which both heat transfer and mass transfer take place simultaneously. In this study, we investigated heat transfer characteristics, the amount of frost deposited, and the surface temperature of the frost layer under natural convection. The procedures of the calculation of the overall heat flux and the amount of frost deposited in the frosting process were proposed. Experimental results were compared with present calculated results, the homogeneous frost growth model, and the unhomogeneous frost growth model respectively.

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Generally, the air conditioning systems are designed based on managing temperature and humidity including outdoor air, which result in low evaporation temperature to manage humidity. We can expect large improvement on efficiency using our new high efficient desiccant system combined with high temperature evaporation type air conditioning by managing temperature and humidity separately. In this paper, we report the problem of the air conditioning system with separation process of latent heat and sensible heat.

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The purpose of this study is to realize features of energy efficiency of desiccant air-conditioning system for dedicated air conditioning system and propose new high efficiency application of dedicated air conditioning systems with desiccant air-conditioner. Many of advanced air conditioning systems, for example, displacement air conditioning system, etc., are intended to reduce energy for only sensitive heat conditioning or space of sensitive heat conditioning. The result show that high efficiency latent heat conditioning system by desiccant air-conditioner combined with these systems bring high efficiency of total air conditioning and advantages against these system with conventional latent heat conditioning systems.

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The purpose of this study is to realize a non-condensing environment by developing a new type of desiccant air-conditioning system with lower energy consumption. In this paper, a displacement air-conditioning system with a desiccant outdoor air-conditioning unit is proposed and the overall energy efficiency of this system is compared with that of the conventional outdoor air-conditioning system. The results show that the system COP of the proposed system is considerably higher than that of the conventional outdoor air-conditioning system.

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This paper describes advanced technology established radiation panel system using roots-aqua heatpump which achieved a good balance between Prevention of global warming and human comfort condition.

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Nowadays, multi-packaged air conditioning system has been often adopted even for large scaled building. Kajima Akasaka Annex, completed in July 2007, is also equipped with multi-packaged air conditioner in spite of a large scaled office building, which is divided into ambient segment and task one to perform both energy-saving and comfortable environment. These design, engineering, study on future capability and state of operations are reported.

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The air-conditioning system that separated the latent heat load and the sensible heat load has attracted a great deal of attention for energy-saving system. We will design the air-handling units of outdoor air (OHU) for latent heat system. OHU can use Task/ambient air conditioning (TAG) system. TAG system are being investigated and are effective air conditioning methods for offices. In this study, subjective experiments with a TAG system were conducted to investigate thermal comfort and productivity by field measurements.

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The use of convective air-conditioning is standard practice in Japan, where the climate is hot and humid during the summer season. There is growing interest in cooling systems, which deal with sensible and latent loads independently, due to its potential for improvement in energy efficiency. This paper describes the use of cooling and heating utilizing radiators installed in rooms. The temperature of the radiator is allowed to run below the dew point, resulting in condensation occurring on the radiator surfaces. Basic characteristics of the system is described, including its energy performance and comfort.

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The classical molecular dynamics simulation was conducted in order to clarify the effects of the surface structural clearances in nanometer scale on a thermal resistance at a liquid-solid interface as well as the static and dynamic behaviors of fluid molecules in the vicinity of the surface. The thermal resistance between the liquid molecular region and the solid walls with nanostructures was calculated by the heat flux and the temperature discontinuity obtained in the molecular dynamics simulations. The geometric surface area change depending on the nanostructures as well as their clearances and the dynamic behavior change of the fluid molecules at the interface depending on the nanostructural clearances cause the thermal resistance reduction depending on the nanostructures at the liquid-solid interface. The thermal resistance reduction mechanism by the nanostructures at a liquid-solid interface was discussed in the present study.

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In this paper, the molecular dynamics (MD) simulations have been carried out to study the effects of the nanostructures on the interfacial boundary conditions at the solid-liquid interface. Simple Lennard-Jones (LJ) fluids have been simulated in the parallel-plate nanochannels using nonequilibrium molecular dynamics techniques. The structure of the solid-liquid interface has been focused and a new definition of the solid-liquid interface at the structured surface has been proposed.

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Precise understanding of thermal contact resistance (TCR) is a key to improve a variety of thermal systems. Though it is fundamental to understand the TCR in nano or atomic scale, there have been reported very few experimental approaches to measure the TCR due to technical problems. We measure the TCR between carbon nanotube (CNT) and solid material (Pt, SiO_2) by using a new device of suspended sub-micrometer Pt hot-film. It is concluded that TCR between CNT tip and SiO_2 surface is 14% of thermal resistance of the CNT itself.

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Precise thermal management is necessary for high heat flux in SiP-mounted semiconductor devices. The purpose of the present study is accurate evaluation of thermal resistance change on the Flip-Chip junction structure in those devices. To measure microscale thermal resistance, we applied a photothermal reflectance method. In this method, thermal properties are extracted from a phase-lag between heating and temperature oscillation at the sample surface, using lasers. We theoretically verified that the phase-lag has adequate measurement sensitivity, and then developed a new measurement apparatus. We measured thermal resistance of Si wafer, confirming that the apparatus operates according to the measurement theory. Furthermore, we preliminary measured interfacial thermal resistance between Si wafer and Au foil.

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The present paper focuses on the difference of thermal boundary resistances at the interface of alkanethiolate self-assembled monolayer (SAM) with hydrophobic and hydrophilic solvents. By using nonequilibrium molecular dynamics simulations, a temperature gradient was imposed across the SAM interface and thermal boundary resistance was evaluated at the both interfaces. It was found that the resistance between hydrophobic SAM and hydrophilic solvent is much larger than that at the hydrophobic SAM and hydrophobic solvent. As one of the influential factors in this difference, the matching of vibrational spectrums of molecules at the interface region was examined.

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Fluid flow in a small region under sub-micrometer (e.g., porous media) is difficult to treat by conventional macroscopic continuum picture. There are many approaches to study flow in sub-micrometer scale by improvement of methods such as Lattice Boltzmann Methods. Other approach is bottom-up from molecular scale, at which fluid is treated as assembly of a large number of molecules. In this paper, we adopt latter to study fluid flow in nano pores by using molecular dynamics simulation with our new boundary condition for flow generation. In this new method, mirror images for the boundary condition are contracted at upstream side or elongated at downstream side to generate flow. We have confirmed that flow can be generated by this method. We also analyze the motion of nano droplet on the solid wall.

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Flow characteristics of gases in a flow channel of about 5 nm in diameter were studied experimentally. As silica-surfactant nanocomposite membranes have a lot of nanoscale channels of about 5 nm in diameter and a straight shape, we used them as a nanochannel. The flow characteristics were investigated by changing gas temperature from -40 to 80℃ and kinds of gases, N_2, Ar, He, CO_2 and R-134a. As the results, they were shown that the flow in the nanoscale channels was governed by surface diffusion flow, the effect of gas species toward gas permeability was not large, and the flow characteristics in the nanoscale channels could be divided into three regions: transaction flow region of rarefied gas flow and surface diffusion flow, the region of monolayer surface diffusion flow and the region of multilayer surface diffusion and movement of capillary condensates, depending on the fluidic gas temperature.

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