An improvement of the digital noise filter is attempted aimed at improving the system for the feedforward control of instability waves in a transitional flat-plate boundary layer. The older control method using the Chebyshev type filter had difficulty controlling the instability waves of plural frequencies. An Inverse Chebyshev type filter is adopted as a noise filter and its characteristics are compared to the Chebyshev type filter. The results show that the Inverse Chebyshev filter can ease the deformation of wave signals compared to the Chebyshev type filter.

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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 due to fouling and concentration polarization in the vicinity of the membrane surface. In this study, we conducted molecular dynamics simulation on the behaviors of water molecules and salt ions to investigate the effects of interaction force on the diffusion (water molecules and salt ions) and the permeation. The results show that the strong interaction force decrease the diffusion coefficient of water molecules and increase the permeation of water molecules.

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In the present study, two dimensional squeeze flow of newtonian fluid with free surface between parallel plates bonded elastic sheets separated at a constant velocity is investigated. Multiphase flow analysis program based on fractional step method, the constrained interpolation profile (CIP) method and projection method is developed, and the motion of free surface taken into account of the elastic deformation of sheets is simulated. The continuum surface force (CSF) model is used to calculate surface tension. Color function identifies a liquid-gas interface. Fluid-structure interaction is calculated using the immersed boundary method. CIP Digitizer method is applied for capturing the moving interface.

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Gas-liquid interfacial flows, such as liquid film flows (also known as wetting flows on walls), are encountered in many industrial processes including absorption, distillation and so on. The present study focuses on detailed descriptions of the transition phenomena between the film flow and the rivulet flow, as well as how such phenomena are affected by wall surface texture treatments. This study develops a numerical simulation technique using Computational Fluid Dynamics (CFD) with the Volume of Fluid (VOF) model as well as a lab-scale experimental testing technique. Through the comparison of two geometry cases (smooth wall and wavy wall), the numerical and experimental results show quantitatively that surface texture treatments can help to prevent the liquid channeling and can increase the wetted area. The main reason for increasing the wetted area on the wavy wall is that the liquid film break-up is inhibited due to the liquid holding and the spreading of the liquid flow in spanwise direction by the wavy surface geometry.

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The liquid film flow applied for the separating technology, for example CO_2 absorbers, is required to increase its interfacial surface with gas in order to improve the separation efficiency, furthermore the smaller liquid flow rate is favorable for the economy. The liquid film flow with low liquid loading, however, breaks up to rivulet flow and reduces its interfacial surface. The present study focuses on detailed descriptions of the transition phenomena between film flow and rivulet flow by changing liquid flow rate and the influences of liquid properties, inclined angle of wall and wall surface texture treatments on the interfacial surface. Results of Computation Fluid Dynamics (CFD) with the Volume of Fluid (VOF) model, which is validated by the lab-scale experiments, show that the pattern of the film flow varies with the kind of liquid, especially liquid viscosity and contact angle. Correlation equations for the wetted area ratio are derived as functions of the dimensionless parameters, Weber number, Reynolds number, Froude number and the liquid contact angle. The wavy surface is more sensitive to the liquid viscosity and the liquid flow rate while it is effective to prevent the film flow from breaking.

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It is known that a droplet is held on the vertically vibrating pool of the same kind of liquid. When the frequency of oscillation is at the resonance of the apparatus, the droplet is found to a certain position on the pool regardless of the initial dropped position. In this case, the lifetime of a droplet is as long as several hours, perhaps because of the larger amplitude of vibration acceleration than the gravity as previously reported. Then we investigated waveform at the resonance frequency to clarify the relationship with the position where the droplet is retained. The amplitude, phase, and average displacement of the surface of oscillating pool were measured by a laser displacement meter and FFT analyzer. The average displacement is relevant to the position of a droplet, while the amplitude and phase are not; in the distribution where the regression plane of the average displacement is subtract, its minimum position is almost the same as the retained droplet.

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The optimum growing temperature of an agricultural crop plant, vegetable and flower and ornamental plants, concentrates and exists in 15-25 degree C. A seasonal temperature change has strong influence on growing of agricultural products. The soil warming for plant husbandry is one of the effective promotion methods of an agricultural crop plant growing. Generally, the ridge warming is performed by warm water circulation of underground. The heavy oil is mainly used for water warming. The experimental results is shown that the soil warming for plant husbandry by geo thermal energy, which keeps 15-20 degree C through a year. The growth promoting effect is proved by the Japanese-mustard -spinach cultivation experiment by using the ground heat at an actual soil. It is clarified that the quantity of soil-warming-heat by using heat pipe.

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This research focused on the methane exchange between lakes and the atmosphere in the Alaskan Arctic Zone. Water samples collected from 29 lakes during summer in 2008 and 2012, dissolved methane concentrations (DM) in the samples were measured. The relationships between DM and lake area were similar to those for Swedish lakes. The methane flux in Alaskan Arctic Zone was 20.3 Gg CH_4 yr^<-1>. Mean methane flux density per lake area (m^2) was 0.799 g CH_4 m^<-2> yr^<-1>. This is about the same level as Swedish and Finnish lakes in no permafrost region. These results suggest that there are no apparent effects of thawing permafrost on DM and on methane flux in the Alaskan Arctic Zone.

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The regulation of safety for Hydrogen gas station requires the temperature of Hydrogen gas lower than 85 ℃ during rapidly filling at high pressure into a FCV tank. Understanding of heat transfer in enclosed pressure vessels is important to achieve safe and rapid filling stations. In this study, temperature response on the wall of enclosed pressure vessel during filling Nitrogen gas was investigated experimentally. The stainless steel vessel was prepared and oriented horizontally with the inlet at the top. The temperature rises of the gas and the inner wall of the vessel was measured during filling Nitrogen gas at the pressure of 1, 3, and 5 MPa. Wall temperatures were measured at three positions on inner wall which were circumferentially putted top, side, and bottom. Heat transfer coefficient was obtained from measured temperature rise.

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Two configurations of power/cooling cycle with ammonia-water mixture are evaluated. At first, an ammonia-absorption hybrid cycle (AAH), which is one of the simplest configurations, is evaluated on temperature entropy diagram to introduce the insight for enhancement. The other configuration, which was proposed by Goswami, is also evaluated. It is a candidate for an enhanced in producing power. The multi-objective optimization for net-work output, refrigerating capacity and total thermal conductance are carried out to derive the pareto front. The optimization is carried out by epsilon-constraint method. The results show that T-S diagram is a good tool for derive the enhancement. Goswami cycle has about quarter cooling capacity while 123.8% net output power comparing with AAH.

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The purpose of this research is to improve the performance of the chemical thermal storage method using Na \2S hydration and dehydration. For the purpose, comparing method of using Na_2S particles and of porous soaked with liquid Na_2S hydration (composite method). Particle material and composite material are dehydrated and hydrated in a chamber under the low pressure. Inside temperature of materials, reaction velocity, and reaction rate, etc. are obtained as an experimental result while both reactions are operated until they converge. As a result, we confirmed that the reaction velocity of a composite material is quicker than that of a particle sample. Thereby, the predominance of composite method was shown.

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Operating characteristics of a liquid-piston Stirling engine in the inverse cycle movement were investigated experimentally. As the result, the possibility of a liquid-piston Stirling heat pump was shown. It is a distinguishing feature that a liquid-piston Stirling engine has no mechanical part in itself. Many people have been thought that a liquid-piston Stirling engine can work as a heat pump when it operates in the inverse cycle. But, there are only a few researches for the characteristic of an inverse cycle movement of a liquid-piston Stirling engine. In this report, forced vibration was given by a piston which was placed on the surface of the liquid column at the open-end of the resonance tube. The vibrations of the liquid columns were observed. It was confirmed that the optimum resonance tube length exists and both amplitude and phase difference reach at the length. In addition, though it was slight, it was confirmed that the low temperature was obtained by the inverse cycle movement of the liquid-piston Stirling engine.

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Critical heat flux of butanol aqueous solution is a few times higher than that of pure water, and the size of generating bubbles is very small. So it is said that butanol aqueous solution is a useful liquid of boiling for the application in cooling devices. In the past, the authors employed the boiling system of horizontal heated wire. In the present experiment, the disc is employed and steady as well as transient tests of boiling is conducted to study boiling heat transfer of butanol aqueous solution. In the tests, saturated as well as subcooled boiling is performed by changing solution density. It is confirmed from the steady experiment that butanol aqueous solution is a usefe liquid of boiling. Some findings such as the appearance of two maximum heat fluxes in boiling curve is also described.

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In the present study we observed Marangoni convection at the vapor-liquid interface of alcohol aqueous solution. It was driven by the surface tension variation caused by temperature and concentration gradients along the bubble surface. Vochten and Petre found that surface tension in aqueous solution of higher alcohol such as butanol aqueous solution has a minimum in the surface tension temperature curves. In higher temperature, the surface tension increased as the temperature increased. We used PIV measurement for the observation of the convection about 1-butanol aqueous solution, ethanol aqueous solution and pure water. In addition, we compared the experiment with CFD simulations. When we kept the heated surface at the boiling point temperature approximately, it was found from this study that the direction of Marangoni convection in alcohol solution was toward the heated surface and it occurred in the opposite direction in the pure water, because pure water does not have concentration gradient. Moreover the velocity of 1-butanol aqueous solution was faster than ethanol aqueous solution. Especially, the velocity of 1-butanol aqueous solution (7.15wt%, 3.0wt%) was 4 times higher than ethanol aqueous solution. We supposed that both the temperature and the concentration gradients acted on the convection effectively.

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In recent years, with the technological advance and the downsizing of the electronic device, the calorific value per unit area continues rising. Therefore, we had applied high-carbon alcohol aqueous solution, pure water and low-carbon alcohol aqueous solution to boiling with impinging flow in mini channel and compared the result with each other. With three thermocouples which were inserted near the heat transfer surface, we calculated the heat flux and the temperature of the heat transfer surface by the temperature gradient obtained from them. The high-carbon alcohol aqueous solution realized higher dryout heat flux than others. In addition, the maximum value of CHF was shown to exist depending on the concentration of the solutions. We investigated the flow velocity on the bubble and liquid interface with the numerical model which analyzed the Marangoni convection mechanism. In this model, butanol aqueous solution also realized that the maximum value of the flow velocity existed for some concentration of the solutions. This suggested the relationship about the mechanism indicating maximum of CHF between the experiment and the numerical model.

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To enhance performance of adsorption refrigerator which is driven by low temperature heat below 100 C further improvement of the adsorber is necessary. Here silica gel and water are used as adsorbing material and refrigerant respectively. The adsorption and desorption process of the silica gel layers packed in the stainless mesh cage formed around cooled or heated copper pipes of 19.05 mm diameter and 0.5m length are studied numerically and experimentally varying particle sizes 0.1 to 5mm and layer thickness between 5 to 20mm. The maximum adsorption difference is obtained for layer thickness 7mm and particle diameter 0.1mm numerically. With decreasing particle diameter, adsorption difference levels off at about 0.5mm. But in experiments 0.3mm particle, which is only available below 1mm diameter, shows far less adsorption. Particles larger than 1mm diameter are for drying use and smaller particles less than 1mm are for column chromatography use. The latter may have different adsorption characteristics.

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The amount of coal ash exhausted from the recent power plants has reached 1,100 tons every year in Japan. Recycling rate of coal ash is 97%, but the number of products made of recycled materials as coal ash is not so large, yet. Since clinker ash commonly has excellent water absorption and retention, we tried to make a sintered porous material from clinker ash. In this study, we tried to produce multilayered structure of sintered porous material with the clinker ash powders of different particle size and to measure their characteristics. As results, it was found that these multilayered structure of sintered porous material showed higher evaporative performance.

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CFC-free technologies have been required. Heat pump which uses zeolites is the devise which can turn out high and low temperature environments not to use CFC. Currently we use two types zeolite which are type-A and type-Y. Considering size of pore which is depended on water molecule, we confirm the type-A zeolites is suitable for using heat pump. Therefore we measured thermo physical properties mainly of type-A zeolites. Then we measured the effective thermal conductivity of packed zeolites to improve heat transfer at that. This time, we used transient hot wire method which is grounded on JIS. We analyzed measured dates and examined estimated value of every each temperature, and found out relationship of effective thermal conductivity and water content.

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Vortex tube (VT) is a simple mechanical device which splits room-temperature compressed gas into cold and hot streams. Generally, it can produce cold stream down to around -30℃ and hot stream up to around 130℃. Since its thermodynamic performance is determined based on the measured temperatures of cold and hot flows discharged from VT, the accuracy of the temperature measurement is important. In this research, two types of temperature probe are used to measure the total temperature and their measurement accuracy is clarified. Moreover, the cold gas temperatures of VT are measured by the total temperature probe in order to clarify the cold flow characteristics.

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Impingement jets are often used for cooling and heating of a surface or a body in the fields of purpose because high heat transfer coefficient is obtained near the stagnation point of the impingement plate where the jet impinges. Heat transfer characteristics using one row and double rows of jets, which impinge on the heated impingement plate, were investigated. Single jet experiments were also carried out. The jet holes with the diameters D of 1 and 2mm were used. L/D were 4, 8 and 12, where L is the distance between the adjacent jets. H/D was from 1 to 10, where H is the distance between the emitter plate and the impingement plate. The experiments were performed with the Re of 250-1600. The surface temperature of the impingement plate was measured using an infrared camera, from which heat transfer coefficients on the surface were obtained. The jet flow was visualized by using a Laser Light Sheet (LLS) methods. The stagnation and the secondary stagnation points were observed on the impingement plate. It was found that heat transfer coefficients are larger in the order of double rows of jets, one row of jets and a single jet. It was also found that the averaged and stagnation Nusselt numbers becomes larger, when L/D is smaller, Re and D are larger.

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Experimental investigation has been carried out on natural convection of air induced around heated horizontal square cylinders. Main concerns were the flow and heat transfer characteristics of high Rayleigh number flows. The experiments were performed in the range of modified Raleigh numbers, Ra_d, from 10^5 to 4 × 10^9. The flows around the square cylinder were visualized with smoke. The result shows that the ascending flows along vertical side surface begin to separate three-dimensionally from the upper surface of the square cylinder when Ra_d* = 2 × 10^6. The local heat transfer coefficients were also measured. The results showed that the coefficients of the upper surface are increased, in particular, with the occurrence of the three-dimensional separation

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Since the heat cannot be removed easily from the air in the confined space like subway tunnels, it can be difficult to maintain the thermal environment in such places at adequate level without mechanical ventilation. Prediction methods of the air temperature help design ventilation of a new line or the improvement of the ventilation of existing lines. Predictions of the thermal environment in subway tunnels have been made in RTRI up to now. As a large data set of thermal environment such as air temperature has been obtained by long-term measurement in a subway tunnel, the prediction method was validated by the data. The result of the validation shows that the difference between the air temperatures calculated by the method and those measured in the tunnel is within about three degrees Celsius.

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In this study, temperature measurement and visualization around a heated disk set in tubular channel have been investigated to understand heat transfer in a reactor of chemical vapor deposition (CVD). A distance between an exit of gas supply and the disc was changed from 10mm to 50mm as same as general CVD reactor. A diameter of tubular channel and a diameter of the disk were 100 mm and 60 mm, respectively. An air flow rate was changed from 2 L/min to 20 L/min. When the distance was 10mm, a gas flow pattern showed the stagnation flow around the disk even if the flow rate was 2L/min. On the other hand, when the distance was 50mm, the gas flow pattern showed unsteady flow with natural convection. These flow patterns could be divided on a graph of a relationship between Reynolds number and Grashof number. From the temperature measurement parallel to the heated disk, Nusselt number distribution was calculated. Furthermore, the relationship between Nusselt number and gas flow pattern has been investigated.

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The present study is investigated quantitatively on the heat transfer characteristics of a horizontal circular pipe in the pressurized fluidized bed. Small scale model of fluidized bed is worked in a pressurized gas, then, the horizontal circular pipe in the fluidized bed was heated electrically. Experiments were carried out for the parameters of bed pressure, bed height and air flow rate. Characteristics of Heat transfer are obtained by measuring the electric power, the heated surface temperature and the bed bulk temperature around the horizontal circular pipe. Relationship between the heat transfer and the flow characteristics were deeply discussed.

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Silicon plate of thickness 100μm has flexible bending, and thus, new added value is provided. In this study, we investigated a new horizontal pulling method using surface tension because the production less than lOOμm were difficult by conventional methods. We draw solidified thin plate from a slit of the crucible. This experiment is a model experiment using the metal with low melting temperature. As a result, we succeeded in obtaining minimum thickness of 100mm, but the process was not stable. Thus, we studied solid-liquid interface position and temperature control mainly to realize a stable process. Solid-liquid interface position depended on the metal temperature, room temperature, and drawing speed. In addition, the experiment where we supplied raw materials into the crucible was successful in obtaining long plate with constant width.

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The purpose of this study is to develop 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 characteristics of direct contact heat storage and release between oil and erythritol. In this direct contact method, if the packed height of erythritol increases, erythritol may be flowed out from a vessel with oil. So to control the packed erythritol height, the effect of a perforated aluminum lattice in the vessel was investigated. The experimental results show that the increase of erythritol bubbles was inhibited by the perforated aluminum lattice. And it is found that the amount of heat release is influenced by the form of perforated aluminum lattices.

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The present paper is suggested using waste heat of middle temperature region (100℃〜250℃) as heat source from factories. The purpose of this paper is comparing the melting and solidification characteristics of the mixture of mannitol and erythritol (C_M=70mass%, mannitol[70mass%]: erythritol[30mass%]) and mannitol as phase change materials (PCMs) in a direct-contact heat exchange type vessel. The experimental results show that the solidification behavior of the mixture of C_M=70mass% has a small porous area and the lower part of the porous solidification layer solidifies rapidly compared with mannitol. Furthermore as flow quantity of oil as a heat transfer medium increases, average heat release speed grows up.

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In this paper, the supercooling duration of promising phase change material (erythritol) in a glass tube was investigated for the degree of supercooling from about 40 to 100 ℃. The melting point of erythritol is 118℃ and the latent heat is 340 J/g. The specimen volume was varied from 0.025 to 16 cm^3. The volume of erythritol is varied using different diameters of the glass tube from 1.02 to 27.3 mm. As a result, supercooling duration was distributed from 3000 min to 20000 min when degree of supercooling was 48 ℃. In addition, it was found that the supercooling duration was decreased with increasing degree of supercooling.

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We report a theoretical study to predict the phase-equilibrium properties of ozone-containing clathrate hydrates based on the statistical thermodynamics model developed by van der Waals and Platteeuw. The Patel-Teja-Valderrama equation of state is employed for an accurate estimation of the fugacities in the gas phase. An infinite set of σ-ε Kihara parameters for ozone were determined, reproducing the experimental phase equilibrium pressure-temperature data of the (0_3 + 0_2 + C0_2) clathrate hydrate. A unique parameter pair was chosen based on the experimental ozone storage capacity data for the (0_3 + 0_2 + CCl_4) hydrate. We determined the three parameters of the Kihara intermolecular potential for ozone as α = 6.815 × 10^<-2> nm, σ = 2.9909 x 10^<-1> nm, and ε × k_B^<-1> = 184.00 K. The prediction with the developed model showed good agreement with the experimental phase equilibrium data within ±2% of the average deviation of the pressure. The Kihara parameters of ozone showed that ozone is slightly better suitability for the structure I hydrate than C0_2, which was used as a help guest. Our model suggests the possibility of increasing the ozone storage capacity of clathrate hydrates (〜7% on a mass basis).

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This study reports the visual observation on the growth and formation of clathrate hydrate crystals in the stream of flowing liquid water presaturated with methane gas. Experimental apparatus used in the present study is devised by inserting a porous pipe inside the reactor thereby allowing the hydrate crystals to form and grow in the liquid water stream. The morphology of methane hydrate crystals grown in liquid water stream varied depending on the system subcooling temperature, ΔT_<sub> . ΔT_<sub> is defined as the difference between equilibrium temperature of the hydrate, T_<eq> and system temperature, T_<ex>. The crystal growth in the bulk of liquid water was observed when ΔT_<sub> > 4.5 K. When ΔT_<sub> is in the range of 4.5 K - 9.0 K, polygonal flat plate crystals were observed growing from the porous pipe surface. At 9.0 K to 10.0 K, the crystal morphology enters the transition phase, where the polygonal flat plate crystals started to change into dendritic crystals. When the subcooling temperature, ΔT_<sub> is greater than 10.0 K, polygonal crystals were completely replaced by the dendritic crystals. On the basis of these observation results, continuous supply of the guest substance will enhance the growth of methane hydrate as the crystals formed in the present study were larger in terms of particle size compared to the previous study. (Ohmura et al., Crystal Growth Design, 5(3), 2005.)

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We numerically analyzed the effect of control methods on 2-D temperature distribution in a vertical plate with varying noise-heat-generation at one corner to minimize the change of the temperature distribution. We studied three control methods: the control using internal heaters in the vertical plate, the control using rod-type lamp heaters, and the control using plate-type close radiators. The control heaters were divided into three zones and they were controlled using the PID control method with monitoring temperatures at three positions in the vertical plate. We found that the control using the close radiators is most preferable to minimize the 2-D temperature distribution in a vertical plate with varying noise-heat-generation. We also studied the effect of monitoring error on the change of the temperature distribution.

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In the present study, a theoretical non-gray rigorous model was established to study the radiative heat transfer through greenhouse covering materials by using Radiative Element Method by Ray Emission Model (REM2). This model was applied to find the difference in thermal performances between silica glass, polyvinylchloride (PVC) and low density polyethylene (LDPE) covering materials. Using the advantage of the previously predicted spectral radiative properties of these materials, accurate estimations of greenhouse temperatures were achieved. In addition, an outdoor experiment was conducted to measure the thermal performances of three rectangular enclosures covered by the mentioned claddings. Enclosures inside, floor and cover temperatures calculated using the rigorous model showed a satisfactory correlation with the experimental measurements

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Because heat treatment application using arc is restricted due to its energy concentration characteristic, authors have been developing magnetically driven arc technology to extend the heating area by arc torch. An alternating magnetic field is applied to a transferred arc and makes the arc column oscillate and therefore the heating area seems to be expanded. However, some anode spots appear on the processing material surface and the continuous arc motion is sometimes spoilt by these spots, which results in a non uniform heat treatment. The authors conclude that use of a non transferred arc is one of the appropriate methods to realize the more uniform heat treatment. Because no current flows into the anode with the non transferred arc, no such spot generation can be expected on the heating object. In this research, the magnetically driven non transferred arc generating device is developed according to the theory of the conventional magnetically driven transferred arc, and generation of plasma jet and its power control with input arc current are confirmed.

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KSAT2 is a nano-satellite developed by Kagoshima Satellite Development Team. KSAT2 will be launched as one of the piggyback satellites of GPM, which is developed by NASA. Since the thermal environment in space is very harsh, the thermal design of the satellite is necessary in order to control the temperature of electric devices installed in the satellite within the allowable limits. In this study, we will clarify the attitude of the hottest and coldest conditions, and decide the most suitable surface finish method of the KSAT2. The authors performed a steady state analysis in various attitude of simplified KSAT2 model. As a result, we obtained the thermal worst condition and attitude of KSAT2.Furthermore we found that the best surface finish method is no-treatment for outer panels and black alumite coating for the two paddles.

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The relation of the flame displacement speeds of turbulent premixed flame obtained by both of an experimental analysis method and a numerical calculation was researched using the three-dimensional DNS database of the turbulent premixed flame. The two-dimensional flame displacement speed is experimentally evaluated by a laser sheet imaging approach. In this study, firstly, the flame displacement speeds were obtained by the numerical calculation using both the three-dimensional set and the two-dimensional component of DNS data, and were compared. It was found that negative flame displacement speed appeared only in the two-dimensional calculation. Secondly, the flame displacement speed was evaluated by the analysis method imitated experimental imaging approach, and was compared with the two-dimensional flame displacement speed obtained by the numerical calculation. As a result, it was found that the statistics of the flame displacement speed differed depending on the way to consider the local velocity in experimental analyses.

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Flame front area of turbulent flame is considered to be dominant to turbulent burning velocity. Flame surface density is an important parameter taken into consideration in some turbulent combustion models. Most of previous studies regarding flame surface density were based on burner flames or numerical investigations. Only a few studies have been carried out on this parameter of spherically propagation flames. In this study, flame surface density of spherically propagating flame was examined. The cross-sectional images of spherically propagating flame were obtained by Mie scattered laser tomograph technique. Burning velocities and configuration of the flames were investigated for iso-octane/air mixtures at equivalence ratio of 0.8,1.0, 1.4. The ratio of turbulent burning velocity increased with the increase in equivalence ratio. The perimeter of the cross-sectional images of the flame increased with equivalence ratio. However, the flame surface density did not vary with equivalence ratio.

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To clarify the effect of radiation on the ignition of clouds of pulverized coal particles, the k - distribution nongray radiation method is incorporated into the multi-phase simulation tool developed by NETL, and then the coal jet flame experiments by Taniguchi et al. (2000) are simulated. Special attention is paid to the effects of scattering of the particles and soot derived from devolatilization of coal particles during the ignition process. It is shown that the presence of soot affects significantly the gas and particle temperatures after the ignition whereas the scattering of the coal particles has unimportant effects on the temperatures as well as the radiative heat sources.

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In this report, temperature and gas generation of pulverized coal during pyrolysis under nitrogen atmospheric condition has been measured to understand heat and mass transfer before its combustion. A furnace was heated at 400 K/h until a setting temperature, TS. After that, the temperature at a wall of the furnace was kept at TS for 0.5 h. For TS = 873K, the gas flow rate had a 1^<st> peak at t = 50 min. A temperature in the packed bed, Tpc, was about 400 K at the time. So, the 1^<st> peak was caused by evaporation of water. As time elapsed, the gas flow rate became increasing at t = 65 min. The Tpc was about 490 K. For t > 65 min, the gas flow rate had a 2^<nd> peak at Tpc = 650 K with exothermic reaction, which was caused by polymerization. At TS = 1073 K, it was found that not only heat transfer but also gas generation due to the exothermic polymerization became more obvious than those at TS = 873K.

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Gravity effect for candle flame oscillation frequency was calculated by numerical simulation. Calculation operated by NIST FDS5 program. Numerical simulation result show that oscillation frequency is increase by gravity increase and oscillation frequency is not change by heat value increase. Therefore buoyancy convection affect for candle flame oscillation and not only buoyancy convection affect for oscillation.

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The purpose of this study is to elucidate flame propagation behavior of three mixtures under application of non-uniform electric field. Three gaseous fuels were mixed with standard air and test fuels were hydrogen, methane and propane. The equivalence ratio of methan-air mixture was 1.05 and equivalence ratio of propain-air mixture was 0.9 becase the flame propagation velocities of methane and propane mixtures were adjusted as same as that of hydrogen-air mixture at equivalence ratio of 0.4. The constant volume combustion chamber was used in test and all tests was carried out at atmospheric pressure and room temerature. The positive or negative non-uniform high-voltage electric fiels were applied to test mixture during combsution by the point-to-plane electrode giometry. The voltage was varied from 0 to 20 kV at every 2 kV. When the positive polarity non-uniform electric field was applied to hydrogen-air mixture, the flame propagation was enhanced because wrinkles on flame were increased by the corona wind. However, the flame propagation of hydrogen-air mixture was not affected by the negative polarity electric field. In case of methane-air mixture, for both polarities, the flame front was lengthened toward electrodes, however the corona wind did not make the wrinkle on the flame front and the combustion was not so enhanced. For propane-air mixture, the combustion was enhanced by both polarity non-uniform electric fields. The corona wind generated the wrinkle on the flame and wrinkles were enhanced by electric field. This is because a lot of ions were included in propain-air mixture flame.

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In previous study, the cellulosic liquefaction fuel (CLF) was made from woods by the direct liquefaction process and the wood tar was used as a solvent, however CLF was not ignited by the compression ignition and was not mixed with diesel fuel. In practical use of CLF, fatty acid methyl ester was used to mix with diesel fuel stably and completely. Therefore, the solubility of CLF with diesel fuel should be improved. In this study, CLF was liquefied by using the mineral oil as a solvent and polypropylene was mixed with wood in order to improve the solubility to the diesel fuel. In experiments, the weight mixing ratio of CLF to diesel fuel was varied until 20 wt.% by every 5 wt.%. In ordinary engine performance test, the compression ignition and combustion characteristics were almost similar to those of diesel fuel and the engine performances were not influenced by mixing ratio of CLF. THC was decreased as the weight mixing ratio of CLF increased, because CLF included oxygen atoms in its molecule. In high load condition, CO and smoke concentrations were also decreased, however S0_2 concentration increased. When 5 wt.% of CLF was mixed to diesel fuel, the diesel engine could be continuously and stably operating for 3 hours without any bad influence on ignition characteristics and engine performance. Therefore, CLF can be practically used as alternative fuel for diesel engines.

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Structures of stretched cylindrical diffusion flame with large curvature were investigated experimentally. Temperature distributions of fuel-diluent mixture/air flames were measured. Fuel was diluted with diluent gases (N2, Ar and He) in order to set the Lewis number Le〜 1. Fuel (Air) was supplied from inside (outside) of the cylindrical flame. Thermal dissipation rates were calculated from measured temperature distribution. In the case of Le= 1, the scalar dissipation rate is proportional to the thermal dissipation rate. Therefore, the stoichiometric scalar dissipation rate was evaluated using the maximum value of the thermal dissipation rates obtained from each temperature distribution. Generally, it is known that the scalar dissipation rate of the counterflow flat diffusion flame increases as the flame stretch rate increases. However, in the case of the cylindrical diffusion flames, the scalar dissipation rate has a maximum value or decreases with the stretch rate.

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Nanometer size particulate matter (PM) has harmful effects on human health. PM characteristics such as size and component emission from flame were required to develop reduction technologies for combustion origin PM. In this study, number concentration and characteristics of PM emission from quenched flame of benzene fuel were measured by a SMPS (Scanning Mobility Particle Sizer) and a combustion type PM analyzer (MEXA-1370PM). In addition, oxidation temperature of PM and its density were also measured by a TGA (Thermo Gravimetric Analyzer) and a Hydrometer. From these results, it was confirmed that PM emitted from quenched flame was more aggregation particle with SOF high mass concentration.

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Effects of O_2 concentration and injection duration on combustion and emission characteristics of diesel spray in a high temperature and high pressure vessel was experimentally examined under low O_2 concentration ambient. It is confirmed that the fuel injection duration has large effect on the shape of heat release rate. As the decrease of injection duration, the shape changed from the normal diesel combustion like one to the smooth heat release rate curve with only one peak which is qualitatively similar to the effect of O_2 concentration. Under the very low O_2 concentration condition, the combustion duration becomes extremely longer as the increase of injection duration which is primarily due to the slow heat release during the later phase of combustion. The CO emission rate increases with the decrease of O_2 concentration and with the increase of injection duration. The NOx emission rate dramatically decreased with the decrease of O_2 concentration, however there existed an injection duration which leads to the maximum NOx emission rate.

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The flow visualization inside the oil film was tried using the method of photochromism. One of the photochromic dyes is dissolved in the PAO and used as a test solution for examining the coloring characteristics and flow visualization. From the systematic experiments, it is confirmed that the spyropyran is a good candidate for photochromic dye under the ambient condition of relatively low temperature range around the room temperature with its long life time of coloring and with its clear color. On the contrary, CMTE is a good candidate for photochromic dye for the usage in the higher temperature range with its longer life time of coloring under the high temperature. In the visualization experiments using the light source of a 3rd harmonic of Nd-YAG laser and the CCD camera, the movement of the oil film with the thickness of 30 nm was successfully visualized and the flow velocity was quantified.

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An experimental study was performed in order to investigate the effects of eccentric location of needle inside a VCO diesel nozzle on internal cavitating flow and primary atomization, so the 10 times large-scaled VCO nozzle with two nozzle holes was employed. The needle was manipulated by a three-dimensional traverse with micrometers. Discussion in this study focuses on the behavior observed at a relatively low needle lift in three cases: 1st case where the needle is perpendicularly positioned from the center of the nozzle, 2nd case where the needle is perpendicularly positioned from locations with slight displacements from the nozzle center close to the nozzle hole, and 3rd case where the needle is perpendicularly positioned from locations with slight displacements opposed to the 2nd case. Differences of spray cone angle and discharge coefficient were hardly apparent between the 1st case and 3rd case. However large difference of spray cone angle was observed between the 1st case and 2nd case when the needle is positioned far from the common plane of the two holes axes. Trend and value of discharge coefficient in 2nd case were different from those in 1st case.

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The characteristics of fuel spray behavior are very important for diesel ignition and combustion process which significantly affect on the engine performance and exhaust emissions. In the up-to-date direct injection diesel engine technological innovations have been considerable. Especially, the injection system such as multi-stage injection and high-pressure injection is significant and then the combustion process has considered to differ from the combustion process of the conventional diesel engine substantially. In this study, using the constant volume vessel, which can simulate the temperature and pressure in the combustion chamber at the time of the fuel injection of direct injection diesel engine and a high speed video camera, the observations of fuel spray, mixture formation and combustion process have been made. On the experiments, the injection system using a piezo-actuator to get a same injection sequence of multi-stage injection in the modern direct injection diesel engine was used to realize a single shot and multi-stage injection in the constant volume vessel. The piezo-actuator using in the injection system with high speed and high load characteristics operate directly nozzle needle. The observations of the spray and combustion process were made on the conditions of different injection rate patterns includeing single shot injections and multi-stage injections.

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The present investigation describes the characteristics of the fuel spray and the interaction with a cross-flow. Under the normal temperature and pressure, the fuel is injected by a VCO injector into an optically accessible rectangular wind tunnel; the direction of the injection is perpendicular to the direction of the cross-flow. The velocity of the cross flow is 9.2m/s while the injection pressures are 5 and 10 MPa. By using the high speed video camera and the PIV system, the spray profile, the penetration distance and velocity distribution are measured. The high vertical and horizontal penetration distance are obtained with the high injection pressure in the cross-flow. Along the direction of cross flow, the horizontal component of the droplet velocity is even higher than the velocity of cross flow in the spray tip region.

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The aim of this study is to investigate the potential of direct injection (DI) for improvement of thermal efficiency of a compressed natural gas (CNG) engine. The thermal efficiency, burning velocity, combustion stability and exhaust emissions of the DI were compared to those of conventional PFI under various engine loads and equivalence ratio conditions. The thermal efficiency of the CNG engine was improved by DI particularly at low engine loads and lean mixture conditions as a result of improved burning velocity. However, at high load condition, the thermal efficiency of DI was lower than that of conventional PFI due to insignificant improvement in burning velocity and insufficient mixing time. The DI showed higher unburned emissions than PFI regardless of engine operating conditions due to insufficient mixing time and corresponding deterioration in mixing quality.

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Combustion of diesel dual fuel (DDF) was investigated using a rapid compression/expansion machine (RCEM). Ignition and spreading of burnt gas region were visualized by a high-speed color digital camera. According to the visualized images, auto-ignition occurs in the pilot-spray with a part of natural gas mixture, then the burnt gas, which is observed as a bright white region, spreads out. In the latter period of the combustion, a dark region, which corresponds to a hydrocarbon emission, still remains between the sprays. For a case of early injection, the burnt gas quickly moves out from a piston bowl to a squish area, so that the natural gas mixture in the center of the bowl does not burn completely. For a case of two-stage injection, injected fuel of the first part diffuses into the natural gas mixture and the combustion.

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