Void fraction and frictional pressure loss were measured in gas-liquid two-phase slug flows in a horizontal micro tube of 200 gm in inner diameter. To measure the pressure loss of the flow, we did not use a pressure gauge but measured with the volume change of gas bubbles. As a result of void fraction, measured data of the gas phase average velocity got into a line in the diagram with total volumetric flux jr as an abscissa. It was thus found that the drift-flux is also effective for the slug flow in a micro tube. As for the frictional pressure loss, the Chisolm's parameter C, in L-M method correlation, was not so small as reported before for micro tubes but as large as the value in conventional pipes.

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Concentration sensor using a hot-wire and sonic nozzle to measure the gas composed of two kinds of gases is fabricated by MEMS technology. When to measure the concentration, high sensitivity and response and precision and not influencing the air flow are important. This research aims to improve of sensitivity and reduce the influence on the air flow by the miniaturization. When concentration changes, thermal conductivity of the gas composed of two kinds of gases is changing. The thermal conductivity changes depending on the concentration and the velocity, though the velocity is kept constant with the sonic nozzle. Heating current flows from Wheatstone bridge to keep constant temperature. The supplied current changes, too, when the thermal conductivity changes. The concentration is indirectly measured by measuring the supply current.

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This paper reports on the interaction of a laminar round vortex ring with a sharp density interface. The deformation process of the ring after interacting with the interface was studied experimentally by both methods of the flow measurement by PIV and the flow visualization based on PLIF. For a 'weak' vortex ring compared with the density difference, having the Richardson number of the order of unity, the ring came to a stop near the interface and then displayed a complicated development. While this development of the ring deformation was similar as interacting with the solid wall, it should be also noted that the mass exchange between upper and lower fluids through the interface was observed in this experiment.

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In this paper, 3-D reconstruction images from digital hologram have been improved by using deconvolution technique. The purpose of the present study is to improve the performance of particle measurement method based on digital holography. This can be applied to 3-D velocity measurement by PIV or PTV. The recording and the reconstruction processes of digital holography are theoretically expressed by using Fresnel-Kirchhoff formula in convolution representation. Reconstructed particles images are expanded in depth direction more than the actual ones. Furthermore, it is assumed that the expanded particle image is shown by the convolution of the actual particle and expansion function (three dimensional PSF). Thus, the actual particles can be obtained by deconvolution with the PSF and the reconstructed images. It is shown in numerical simulation that the accuracy of particle position can be improved for both cases with multiple scattering and non multiple one.

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Pressure sensitive paint (PSP) is a very powerful measurement method to visualize pressure distribution on solid surfaces in experimental fluid dynamics. Since PSP is a noncontact method using emission of luminescent molecules, it is advantageous to apply the technique to rotating solid surfaces, e.g. rotor blades of turbomachinery. However, application of PSP to turbofans with small pressure rise, e.g. propeller fans, has never been reported, because of low pressure sensitivity of PSP for measurement in low gauge pressure conditions. In this research we show the method for applying PSP for measurement of pressure distribution on suction surface of a propeller fan using a priori calibration, and validate the sensitivity of PSP for pressure to discuss the feasibility of PSP for the application for propeller fan. Moreover, the sources of errors caused in measurement of pressure distribution on blade surface using PSP are examined.

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Cold spray is a relatively new coating technology that produces deposits by high velocity impact of feed stock powders onto the substrate in order to impart corrosion resistance, abrasion resistance and so on. The purpose of this study is to clarify the flow conditions in the supersonic nozzle for cold spray. We measured the static pressure of the divergent nozzle using the pressure sensors attached to the nozzle. In addition, one-dimensional numerical analysis was performed, and was compared with the experimental result. As a result, the choked position in the experiment was found to be different from the one-dimensional analysis by the gasdynamic throat. Therefore, we calculated the position of the gasdynamic throat by the formula derived from theoretical analysis of quasi-one dimensional steady flow of insulation friction. However the error was negligible. Thus, the formula could not be used in this study. Assuming that there is the gasdynamic throat, the result of one-dimensional analysis was close to the experimental values.

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In this study, a micro-actuator was designed to produce the high pressure using the electrostatic force and the evaporation of the working fluid. The dielectric liquid of HFE-7100 was used as working fluid. The electrostatic force was induced at interface between the liquid and air by the application of high electric field, and the vapor pressure was produced by the application of heat. The maximum pressure induced by the electrostatic force was 1000 Pa with the application of electric field, 7 kV/mm. Also, the maximum pressure induced by the evaporation of the liquid showed 1000Pa with the application of calories, more than 3.50 W. The pressure induced by the both the electrostatic force and the vapor pressure was 1200 Pa with the application of electric field, 4 kV/mm, and of the calories, 3.65 W.

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This study investigates separation control using vortex generator jets on a test model which is subjected to favorable and adverse pressure gradients. The final target of this study is to control the separation on the aft-loaded turbine blade in the unsteady main flow. The numerical simulation is to control the separation using steady vortex-jets (VGJs) in the steady main flow. The test model has two curves to create a shape for establishing a pressure gradient typical to an aft-loaded turbine blade. There are 7 holes, and these holes have a 5.0mm diameter with a 30-degree or 45-degree pitch angle and a 90 degree skew angle. The injection location is set at the point of maximum velocity on the test model. The velocity of the jet is fixed at four times the velocity of the main flow. It is found that the effect of separation control is obtained from a 45-degree pitch angle.

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The injection and suction effects on the turbulence are important. In the present work, the turbulent channel flow with the localized injection and suction sections are calculated by means of the direct numerical simulation. In the case of the strong injection and suction velocity, the flow separation and reattachment phenomena occur behind the injection section. The injection and suction flow gives a great influence on the distributions for the mean and fluctuating quantities.

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Under-water glider is the glider to use for environmental researches in lake and sea. The Reynolds number of flow around under-water glider is between 1 X 104 and 1 X 105. In this study, aerodynamic characteristics of under-water glider at low Reynols number were investigated by the towing water tank experiment and numerical analysis of two-dimensional wings. The experimental data were obtained by the measurements of the lift and drag force acting on the under-water glider model. Planforms of wing of model are rectangle, taper, and sweptback wings, and aerofoils of wing are flat plate, NACA0012, NACA0008, NACA6406, NACA3310, SE4410 which is the cross section shape of flamingo's wing, and Remodeled SE4410 which remodels lower surface of SE4410. As results of experiment, the difference of planform of wings has few effects on aerodynamic characteristics and the lift-drag ratio of NACA6406 is the largest of aerofoils. As results of numerical analysis, pressure coefficient of lower surface of SE4410 is larger in front and rear range and smaller in central range than NACA3310, and Remodeled SE4410 can improve small pressure region of SE4410.

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In recent years, the fine-honeycomb consisted of very small cells has been developed. The pressure drop and turbulence reduction by fine-honeycomb are examined experimentally. Four kinds of fine honeycombs are used, and one kind of mesh screen is used for comparison. The results show that the pressure drop of the fine honeycomb is approximately proportional to the thickness of fine-honeycomb. The effects of the uniformization of mean velocity and the turbulence reduction can be established by using the fine-honeycomb. The turbulence reduction is comparable in both case of the fine-honeycomb and the mesh screen.

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Vortex tube is a simple mechanical device which splits compressed gas into cold and hot streams. It can produce cold stream down to around -30-C and hot stream up to around 130-C. Vortex tube is use in a wide variety of industrial fields, especially as a cooling device. Until now, there are a lot of theories about thermal energy separation phenomena inside the vortex tube, however, these theories are still debatable. In the existing literature, a lot of researchers used air and nitrogen as a working fluid. In this research, helium and air are used as a working gas and the experimental results are compared with theoretical result in order to deeply understand the mechanism of the temperature separation of the vortex tube.

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In order to apply the lattice Boltzmann method to a flow problem of magnetic suspensions, we have investigated the feasibility of the viscosity-modifying method that is expected to be a technique for sophisticating the activating method of the particle Brownian motion based on fluctuation hydrodynamics. We have addressed a magnetic suspension in thermodynamic equilibrium to clarify the influences of various factors such as the roughness of a lattice system and the volumetric fraction of magnetic particles on the scaling coefficient of viscosity. From the snapshots and pair correlation functions of magnetic particles, it is seen that the viscosity-modifying method can show good agreement with the results of Monte Carlo method in both quantitative and qualitative points. This good agreement is almost independent of the roughness of a lattice system if a relatively fine lattice system is used. The scaling coefficient of viscosity is almost constant and independent of the strengths of magnetic particle-field and particle-particle interactions, and also is almost constant for the variation of the volumetric fraction and the number of particles for a given lattice system unless a coarse lattice system is used. We may conclude from these results that the lattice Boltzmann method with the viscosity-scaling procedure is quite a possible technique for simulating a flow problem of magnetic particles under a non-uniform applied magnetic field.

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The canal structured road is built half underground, and it consists of opening and close duct. In the canal structured road with narrow openings, it turned out in the former work that the breathing effect for ventilation is suppressed. Then, the phenomenon in which generating the mass flow by the inhalation and the exhalation by setting up the obstacle board in closed duct, and increasing the breath value is quantitatively evaluated by the numerical analysis. A continuous running of the cars is imitated by the sliding mesh function by using 3D numerical analysis as a method for analysis. As a result, Inlet flow is decreased by 29.5% by setting up obstacle boards in closed duct, and the breathing value has increased by 5.47%. Moreover, it was observed that the mass flow was generated in the opening.

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Water splash caused by an elastic tire rolling on a wet road is simulated using SPH method. Fluid-structure inter action model is newly proposed to couple the fluid motion and the elastic tire. The result shows that the water discharge capability strongly depends on the grooved patterns, and the tire receives lift and drag forces from the water.

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Water shortage due to rising populations and economic development become a serious problem around the world in the 21st century. For this problem, reverse osmosis membrane method is useful technology to secure water resource. This method has a problem that separation performance falls with operating time. Concentration polarization and fouling may occur at the nearby surface of membrane. We thought that prompting transfer of salt ions inhibits the phenomena, and we calculated behaviors of salt ions in bulk water by using molecular dynamics simulation. In this study, we discussed the effects of pressure, temperature and shear action on the diffusion of salt ions. The results of the calculations are as follows. (1)The diffusion of salt ions isn't affected by pressure. (2)The diffusion of salt ions becomes high with a rising temperature. (3) Velocity gradient of shear direction become great with a rising shear velocity, so that it is expected that the diffusion of salt ions become high with shear action.

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The electrochemical heat pump is a heat pump using endothermic and exothermic reactions at lower temperature side and at higher temperature side, respectively. The heat pump is operated with electrical power input. In this study, we fabricated an experimental cell of 2-propanol dehydrogenation reactor and measured fundamental electrochemical characteristics. As a result, maximum endothermal quantity of 440 W/m^2 was achieved with Pt-Ru/carbon cloth electrodes. Continuous deterioration has been measured in the endothermic reactor. The experiments that clarifies the cause of deterioration have been conducted and the results are discussed.

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As a substitute method for conventional chemical or mechanical oxide layer removal of metal surface, an application of vacuum arc has been studied. In this method, the oxide layer of metal surface is removed by cathode spots which appear on the cathode surface in low pressure arc. It has been confirmed that flat surface oxide layer on a metal plate can be successfully stripped. Our previous study shows that this method also can be applied to different type metal surface such as cylindrical pipe inside. However, a problem of non-uniform removal is still remained. In this research, an additional anode current path is set to the arc electric circuit and its influence on oxide layer removal is investigated.

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Vacuum Arc cleaning to remove oxide layer on metal plate opposite side to anode was demonstrated. It was confirmed that cathode spots could exist on the opposite side and removed the oxide layer as well as the case on the anode side. The cathode spot behavior and the removal characteristics of oxide layer were investigated, and some charges caused by different experimental conditions were revealed.

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Mg alloy has a lot of useful properties and its application has been enlarged to various industrial products. However, it has poor corrosion resistance and therefore surface treatment is necessary. In this study, zinc oxide film formation is tried on magnesium alloy surface with RF oxygen plasma in order to improve corrosion resistance preserving good electrical conductivity. Ar gas in addition to oxygen is used to assist an easy plasma production, and the influence of argon on coating film characteristic is investigated.

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The effect of solid particles on the performance of looped pulsating heat pipe (PHP) has been investigated by using water, ethanol and R141b as working fluids. The PHP is made of copper tubes with 3mm OD and 2mm ID, and the number of turns is 12. Lengths of heating, adiabatic and cooling sections are 50mm, 100mm and 50mm, respectively. In order to improve performance, particles of various size and material, that is, alumina particles (10pm, 0.6pm) and copper particles (20p,m, 10pm, 3pm), were added into working fluids. The PHP was working in bottom, horizontal and top heating mode. In case of water containing alumina particle, it was found that heat transfer performance was enhanced in all orientations. In all cases of R14 lb containing particle, heat transfer performance was also enhanced. However, in case of ethanol containing alumina or copper particle, there was no great difference compared with pure fluid. When base fluid was water, the liquid plug oscillation was enhanced significantly by adding particle in proper concentration. On the other hand, in case of R141b, particle addition had no significant effect on the liquid plug oscillation.

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Aiming at utilizing solar energy properly, we study a top-heat thermosyphon. Water is used as a heat transporting medium. Top-heat thermosyphon is a device which delivers heat from higher place to lower place without using an external pumping power. Ito et al. developed a top heat thermosyphon with shorter rise time for operation, which we use in the present experiment. It consists of heat collecting, evaporation, condensation, buffer chamber, and heat exchanging units. The solar input energy varies time to time. Therefore, we are interested in lower input energy. It was confirmed that the system can be driven by input power below 100 W.

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Bubble-actuated circulating heat pipe, BACH, is one of new types of heat pipe, utilizing buoyancy force of vapor bubbles generated at bubble-generation part for liquid circulation. This research aims to develop top-heat type of the BACH consisting of heated section, cooled section and intermediate cooled section. The bubble buoyancy force acts only at between the heated section and the intermediate cooled section, realizing liquid circulation for heat transport from the heated section to the cooled section. Characteristics of heat transport and internal flow of the BACH were investigated by experimental measurements and model calculations. The working fluid was water or HFE-7100. As a result, heat transport rate of the top-heat BACH is affected by several parameters, especially by temperature difference between heated section and cooled section, 〓T_w,hc, temperature difference between heated section and intermediate cooled section, 〓T_w,hc, and upflow pipe length, L_1.

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In this study, a heat pipe system was installed into the mold used in the polymer processing to enhance the heating and cooling rate of the mold as well as to reduce the required thermal energy for the temperature control of the mold, and the characteristics of the system were experimentally investigated. The result showed that the maximum heat flux value of 18 kW/m2 was achieved at the individual operation. By using the system, thermal energy can be transported between a pair of the molds in the sense of thermal district. The result showed that the maximum heat flux value of 8.0 kW/m2 was realized under the thermal energy exchange. And it was expected that the energy consumption to control the mold temperature would be reduced.

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Experiments have been carried out to elucidate the rise effect of human body temperature by taking a bath of Corona nano mist sauna based on the water fragmentation method. The effect of Corona nano mist sauna is analyzed by comparing with the data obtained from the hot water bath and by solving the heat and mass transfer equation about human body. Temperature and relative humidity in Corona nano mist sauna are 40 -C and 98%, respectively, and temperature of hot water bath is 41 to 42 -C. Time duration of bathing is 20 min for the both of Corona nano mist sauna and hot water bath. The main acquisition obtained from the study is as follows that Corona nano mist sauna brings it possible to promote the heat production from body by the increase of metabolism.

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Formation process of metallic ultra fine particle (UFP) using thermal plasma has not been completely clarified yet. In present study, aggregation process of Ni, Al and Ni-Al gaseous phase have been simulated by molecular dynamics (MD) method. Functional interatomic potential for Ni-Al interaction is empirically optimized using reported experimental data of thermodynamics and elastic constant of NiAl intermetallic compound. Progress of aggregation is quantitatively analyzed and its approximative formula is suggested from viewpoint of kinetic theory of gases.

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The evolution characteristics of degradation gas from highly densified biomass briquette called Bio-coke (BIC) are experimentally and numerically investigated. In the present study, evolution rates of both volatile and water from the BIC sample are determined by Arrhenius equations and the constants such as frequency factors and activation energies are given by the experimental results of thermo-gravimetric analysis. It is confirmed that the analysis model used in the study can qualitatively describe the gas evolution from the BIC sample. Rapid increase in the gas evolution rate is identified when the BIC sample ( 0 20 mm x 10 mm) is heated at an end face of the sample. This can be attributed to the finite volume of the BIC sample; the rapid temperature increase can be observed after the water in the sample is completely released. The volatile/water ratio in the evolution gas takes constant value at heat flux higher than 50 kW/m2 while the ratio gradually increases with time at the low heat flux case (25 kW/m2).

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From a viewpoint that waste paper is effectively used as thermal energy resources, copy paper, printed copy paper with toner and raw toner were decomposed under constant heating rate and constant temperature conditions in an image furnace with changing ambient 02 concentration in order to investigate their thermal decomposition and combustion characteristics. Mass reductions of them during the thermal decomposition were measured by an electric-micro balance. The gas compositions produced by the thermal decomposition and combustion processes were analyzed with a gas analyzer. Moreover, elemental analyses of the printed copy paper before and after thermal decomposition were carried out using ICP-MS. As a result, the copy paper began to decompose at about 500K under the constant heating condition, and the temperature was close to the decomposition temperature of cellulose. The decomposition temperature of printed copy paper with toner was slightly lower than that of copy paper. As for the gasification behavior, the peak concentration of CO in the gas product from copy paper decomposition was the highest in 10% 02 condition when the ambient temperature was 1073K. The gasification behavior of printed copy paper with toner was similar to that of copy paper. In the elemental analyses of the printed copy paper before and after thermal decomposition, Fe, which was contained in the toner, was mainly detected.

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The objective of this study is to suggest a new method to predict the stability limit of high temperature air combustion. For the first stage of this study, the flamelet equation is solved numerically to investigate the effects of the scalar dissipation rate and the dilution with burned gas on ignition delay. Methane was used as fuel. Ignition time is defined as the time at which a temporal increase of maximum temperature becomes maximum. The ignition delay time increases with the scalar dissipation rate in the higher range of x. However, in the lower range of x, the time decreases with x. The ignition delay time based on the maximum temperature includes durations of radical pool growth and of movement of most reactive region. In the lower range of x, the increase in the movement speed decreases the ignition delay time with x. With the increase in the dilution ratio K, the ignition delay time decreases, and then increases. This trend is attributed to the increase in temperature and the decrease in species concentration with K. The introduction of chemical characteristics time provides the generalization of ignition delay time for all dilution ratios.

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The effects of convection flow on ignition of a paper sheet under super gravity condition were investigated by using a spin tester. The spin tester can change the gravity level from 1G to 15G The space under the paper sheet was changed to clarify the convection effect under the paper and bottom wall. Convection flow under the paper sheet was analyzed by PIV. As results, it was found that velocity of convection flow quickened with increasing the gravity level and with spreading the space under the paper sheet. Also ignition of paper sheet was promoted with increasing the flow velocity.

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As a fundamental study on spontaneous ignition of fuel spray, spontaneous ignition of a droplet pair in hot air was numerically studied. Calculation code was developed by the authors, and the effect of inter-droplet interference was investigated. First, the calculation was done without chemical reactions, and only the vaporization behavior was examined. As inter-droplet distance decreases, the vaporization of each droplet was suppressed because of mutual cooling effect. Therefore, in the beginning phase, fuel concentration in the gas phase was lower for shorter inter-droplet distance. However, after a while, the fuel vapor layers around two droplets overlapped, and shorter inter-droplet distance led to higher fuel concentration because of duplicated fuel source. Next, the calculation was done with detailed chemical kinetics. Under a certain condition, it was observed that cool flame appeared on the outer side of the droplet pair, and then propagated into the zone between two droplets.

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Hovering phenomena of a high-temperature copper disk brought into the proximity of a water-containing porous material plate is investigated experimentally. Heat transferred from the hot disk produces vapor that flows along the small clearance between the disk and the porous plate. The vapor flow may establish a pressure field that acts to repel the body away from the plate surface. The repelling force may just balance gravity, allowing the hot body to hover over the porous plate. Observed hovering behavior can be classified into four typical stages, each of which depends on the temperature range of the hot body. Measured hovering heights are compared with the predictions by the theoretical model.

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Heat transfer and flow characteristics of ammonia-water mixture evaporating inside an internally spirally grooved horizontal steel tube with 12mm average inner diameter were investigated with considering the gas-liquid phase equilibrium characteristics of zeotropic mixtures. The circumferentially averaged heat transfer coefficient reached its maximum as the quality approached about 0.6 but decreased abruptly as the quality increased. The circumferentially distribution of wall temperature were also discussed for ammonia-water mixture, and their trend were similar to those for pure ammonia.

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RPI model is a numerical model applied to analysis of subcooled nucleate boiling heat transfer. To evaluate the accuracy of this model, experiments and numerical analyses on vertical upward boiling flow were performed in this study. The test section of experimental system has an annular channel consisted of an acrylic tube and a rod heater located in the center of the tube. The tube is 1500mm in length and 24mm in inner diameter, and the heater is 12mm in outer diameter. FC-72 under atmospheric pressure condition was used as a working fluid. In analyses, thermal-hydraulic calculations were conducted by using RPI model and a commercial code, FLUENT. By comparing analytical and experimental results, it was found the radial distributions of void fraction obtained from analyses were in good agreement with the experimental data as long as the value was smaller than 0.2. However, the rise of void fraction caused increase of the error between calculated and experimental results greatly. These results mention that RPI model cannot be applied to calculation in the condition of high void fraction.

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To realize absorption refrigerating machine for household use, further downsizing of the whole unit is necessary, especially for the main component of absorber. The absorber pipes are set commonly in horizontal or vertical direction, but if they are wound spirally, more pipes are accommodated into low space. Absorption performance of typical absorber condition is measured experimentally in film Reynolds range of 20 40. Estimation of the absorption rate is done using the model of Kaynakli et al. They show fairly good agreements.

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To explore behavior of near extinction flamelets in turbulent premixed flames, emission intensities of OH, CH and C2 radicals of hydrocarbon-air premixed flames have been examined using the newly developed emission spectroscopy system. It has been shown in our previous study that the emission intensity ratio of 515nm/470nm bans of C2 radical uniquely depends on the temperature of unstained methane/air and propane/air flames. In the present study, dependence of the emission intensity ratio of 515nm/470nm bans of C2 radical on the strain rate has been examined using a counter flow burner. As the strain rate increases, both the flame temperature and the emission intensities of C2 radical decreases. The flame temperature monotonically decreases as the emission intensity ratio of 515nm/470nm bans of C2 radical decreases. It is concluded that the temperature of a flamelet of turbulent premixed flames can be estimated by measuring the emission intensity ratio of 515nm/470nm bans of C2 radical.

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Absorption spectra of the oxygen molecule A-band transition (ANNAJJ =P11Q10, v=392.3220 THz) are measured by current modulation of a DFB diode laser. We carry out measurements under two kinds of conditions. One is atmospheric open air in 298 K with an absorption length of 0.03 m at a repetition rates from 0.1 to 10 kHz, and the other is atmospheric air in 298 K in a cylinder of a Stirling engine which has a diameter of 0.02 m and length of 0.02 m at a repetition rate of 1 kHz. The scanned range of the light frequency is about 40GHz. We use a balanced detector and a 12-bit AD converter to reduce the noise level. The evaluated noise levels of the spectra are 1.7 x 10-5 at 10 kHz for the former case and 3.1 x 10-5 at 1 kHz for the latter case, and these values are about 2.5 and 4.4 times larger than the shot noise limit, respectively. We confirme that the shapes of the measured spectra are reproduced by calculation assuming a condition of 1 atm and 298 K.

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The flame propagation phenomenon of fuel droplet array has been studied for basic research of the spray combustion mechanism. The investigations on fuel droplet-array combustion have been conducted by microgravity experiments for research on essential mechanism of spray combustion. The fine fuel droplets spray during combustion, which partially evaporated prior to flame propagation. It is essential to consider the influence of pre-evaporation of fuel droplets on combustion for better understanding of spray combustion mechanism. In this study, it was performed that measured preevaporating vapor concentrations of the hydrocarbon fuel droplet using infrared absorption method based on the Beer-Lambert law. The Beer-Lambert law relates the absorption of light to the properties of the material through which the light is traveling. It was utilizing that the absorption wavelength due to the stretching vibration of CH bonds in hydrocarbon fuels, such as n-decane were same as He-Ne infrared laser wavelengths (3.39 gm). Infrared absorption measurements were carried out in two stages. (1) Calculation of the extinction coefficient E. It was performed that the measurement of 4 conditions of equivalence ratio could be calculated extinction coefficient 8.7x10-3 (equivalent ratio' ・ mm-1) (2) Measurement of vapor concentration near n-decane droplets. Measurement of the n-decane vapor concentration and thickness were performed in five conditions at 300, 350, 400, 450 and 500 K. It was able to measure the fuel vapor concentration near fuel droplets.

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The authors have been developed the electro-magnetic spectrum absorption technique by using a specific bands at the molecular oscillation regime of far infrared rays for realization of high energy saving and low emission of CO_2 in the fossil fuel combustion. This technique makes it possible to obtain high efficiency of temperature exchange between combustion tube and working fluid at the heat exchange region. The verification test has been carried out by the wick diffusion flame and the practical combustor such as house boiler. From these results, the temperature rise ratio obtained by utilization of the radiant material may be around 5 to 15%, though it depends on air or water as working fluid. The principle is very useful to achieve the high energy saving and low emission of CO_2 for fossil fuel combustion.

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Sprinkler equipment (hereinafter, SP) is installed in many building in accordance with Fire Services Law. It is well-known that SP has high performance for suppression. However, SP would have other effects expected in fire. For example, the cooling effect in compartment, the cooling effect on building structure and the reduction effect on radiant heat flux from fire. However, the influence of SP on radiant heat flux has not been researched. In this paper, the reduction effect of radiant heat flux through SP droplets was investigated by full-scale experiments. The fuels used for the study are n-heptane and ethanol. The experimental data indicates that infrared energy of fire is absorbed by SP droplets. And, it depends on size and total amount of SP droplets. Moreover, the reduction effect on radiant heat flux was calculated by the Mie theory. As the result, it was consistent with experimental data in case of ethanol fire. On the other hand, n-heptane fire did not agree with them. This is probably influenced by hot smoke layer including many soot particles generated by combustion.

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In this paper, degree of supercooling of promising phase change material (erythritol) in a glass tube was investigated for the volume from 0.0040 to 15 cm3 and the contact area from 0.40 to 27 cm2. The melting point of erythritol is 118 ℃ and the latent heat is 340 J/g. The volume of erythritol is varied using different diameters of the glass tube from 0.40 to 27 mm. In the experiment, the melted erythritol in the glass tube was cooled from 150 ℃ to 30 ℃ at cooling rate of 0.5 ℃/min. As a result, the degree of supercooling was largely depended on the volume of erythritol and significantly increased with the decrease of the volume of erythritol.

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An experimental study of solidification is performed for a hypoeutectic sodium nitrate solution in a confined rectangular vessel with varying initial concentration. The experiments have been conducted by heating the lower wall of the vessel and cooling the vertical cylinder. We investigate the development of its temperature and concentration distribution in the liquid region during the solidification and its effect on the solid layer thickness formed around the cylinder. The growth of the solid layer, which accompanies solute ejection to liquid region, leads to double-diffusive convection and form a sharp density interface. Across the interface a drastic change of temperature and concentration is observed. Therefore, the solid layer thickness undergoes a dramatic change when the interface passes.

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This study is a basic research to develop a miniature thermoacoustic cooling system. A miniature standing wave thermoacoustic refrigerator was produced experimentally. The device consists mainly of an acrylic tube in which the one end is open and the other end is closed. A stack which is a regenerator was inserted into the tube. A honeycomb ceramic was used as the stack in the refrigerator. The sound wave for input into the tube was generated by a speaker mounted at the open end of the tube. It was confirmed that temperature gradient in the stack was generated and the temperature difference between the hot end and the cold end of the stack was greatly influenced by the operating frequency of sound wave supplied from the open end of the tube. In addition, it was found that the temperature increase at the hot end of the stack was suppressed by the simple heat exchanger manufactured from copper tubes in which water is circulated.

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Air velocity and temperature distributions in an aircraft cabin are calculated using 3-dimensional computation fluid dynamics code (STAR-CCM+). Calculation model is one row of sheets in an aircraft cabin (2 m in height, 1.25 m in half width, 0.8 m in length, and two passengers). Relations between air-conditioning conditions (air-inlet position, outlet position, inlet temperature, and velocity) and thermal comfort of passengers are examined. Air-inlet positions and outlet positions are examined at the ceiling, the upper sidewall, the lower sidewall, and the front sheet-wall. Calculation results show that the best condition is that two air-inlet positions at the front sheet-wall (2 m/s, 20-C) and the upper sidewall (10 m/s, 15-C).

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In a car under summer solar radiation, it is well known that the temperature in a car cabin becomes very high and is found to be over 90 degree C on the top of the front dashboard and also air temperature around the driver's seat were over 65 degree C. Thus, ventilation system is one of the effective methods for keeping comfortable thermal environment of a car cabin. In this paper, we conducted experiment and numerical simulations under the conditions that ventilation cold air came into the cabin forcibly from face mode vents and hot air in the cabin was exhausted freely from a rear duct located on rear dashboard, and examined the ventilation effects on inlet mode and at different flow rate. It was clarified that foot mode was the most effective inlet mode for temperature mitigation around driver's seat, and the increase rate of temperature mitigation according to the increase of the ventilation flow rate in foot mode is larger than face mode.

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In this study, effects of dilution with CO, on combustion mechanisms and the local burning velocity of two-component fuel mixtures of DME, hydrogen and methane were investigated by chemical kinetics computations. Lean and rich mixtures having nearly the same laminar burning velocity were prepared by adding CO_2 to mixtures where the fuel mixing rate 6 is varied from 0 to 1 at equivalence ratios of 0.4-3.0. As a result, it is elucidated that Markstein numbers of mixtures diluted with CO, are smaller than that of mixtures diluted with N2. Those of lean mixtures changed monotonically with increasing 6 depending on the Lewis number, however, those of moderately and highly rich flames showed a complicated trend in each condition with change in the equivalence ratio and 6. These characteristics of response to flame stretch were discussed in light of the chemical reaction mechanisms.

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This study tried to apply biomass fuel to burner combustion at high load. Water was used independent of emulsification to reduce toxic emission. A new injector was first developed. The injector mixes fuel rapidly with water inside of the injector with support of atomizing air. The mixture composed of three-fluid is injected as spray into a flame stabilizer of burner. Gas oil, soybean oil and water-emulsified soybean oil were used as fuel. The controllable parameters in the experiment were fuel type, flow rate of fuel, atomizing air, secondary air and water. The concentrations of NOx, CO, CO_2 and PM were measured. Investigation of emission performance of this injector shows that the internally rapid mixing type of injector is useful technique to introduce water into burner combustion. The injector emits exceedingly less particulate matters at high load. NOx is reduced with the use of water. NOx emission is strongly dependent on water flow rate.

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High-temperature air combustion is promising solution for the reduction of NOx emission. For downsizing the combustion system, we used a catalytic combustion for generating the highly preheated oxidizer with low oxygen concentration. In this combustion system, high-temperature air combustion was performed by a fuel jet flame in the high-temperature section right after the catalytic combustion. The temperature and oxygen concentration of the oxidizer depended on the equivalence ratio and the inlet velocity of the mixture flowing into the catalyst. In addition, the uniform and the non-uniform catalytic combustion were observed with the conditions. The lifted turbulent flame was observed on the fuel jet and the lifted height decreased with decreasing the gas velocity and increasing equivalence ratio of the oxidizer, and also with increasing the fuel jet velocity. The fact that the reduction of NOx emission was correlated with the lifted height of the flame implies that the turbulent mixing of the fuel jet and the oxidizer has a significant influence on NOx emission. Furthermore, NOx emissions were really reduced under uniform catalytic combustion conditions, whereas NOx emissions under some non-uniform catalytic combustion conditions were comparable to or higher than that without the catalytic combustion system. This is probably because the oxygen concentration of the oxidizer was not low enough under the non-uniform catalytic combustion conditions. Consequently, an appropriate management of catalytic combustion is necessary for low NOx combustion.

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Homogeneous Charge Compression Ignition (HCCI) combustion has attracted widespread interest because it achieves high efficiency and can reduce particulate matter (PM) and nitrogen oxide (NOx) emissions simultaneously. However, combustion proceeds extremely rapidly in the HCCI process due to simultaneous ignition at multiple locations in the cylinder. Accordingly, the rapid nature of HCCI combustion must be moderated in order to expand the operating range on the high load side. Methods of accomplishing that include the use of a blended fuel and supercharging. In this study, experiments were conducted to investigate the effects of such methods on moderating the rapidity of HCCI combustion. An air-cooled single-cylinder test engine fitted with an external supercharger was used in the experiments. The effects on combustion of varying the heating value of the injected fuel and the intake air pressure were investigated using dimethyl ether (DME) as the test fuel. In addition, a blended fuel of methane and DME was used to examine the effects on combustion of varying the fuel mixing ratios and the ignition timing. In both sets of experiments, the HCCI combustion process was analyzed by using a spectroscopic measurement method and measure the light absorption characteristics. The results revealed that it was also observed that the rapidity of HCCI combustion can be moderated by suitably controlling the temperature fields in the combustion chamber on the basis of the mixing ratios of methane and DME and the application of supercharging.

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This paper describes the effect of axial angle on mixed convection in horizontal square duct with heated and cooled opposite walls by the three-dimensional numerical analysis. The velocity fields and the pressure and temperature distributions obtained by SIMPLE method using dimensionless governing equations. The QUICK scheme was applied to the convection term of momentum and energy equations. The analytical condition was assumed that the axial angle 0 was 37 conditions in -π/2≦0≦π/12. Numerical results show that the three-dimensional flow behavior was influenced by axial angles. In generally, the large recirculation flow, swirl flow, was generated in the duct, and tow recirculation flows appeared inside of large recirculation flow. However, in case of large axial angle, 0>5π/12, Benard-Type flow was generated in the duct. The pressure drop ratio and the heat transfer behavior were discussed corresponding to the flow, and the maximum heat transfer was taken near the 0=π/8.

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