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村田 圭治, 岡本 圭佑, 中畑 仁志, 荒賀 浩一
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This paper is an experimental investigation on forced convective boiling in a mini-tube. First, frictional pressure drops were measured in adiabatic condition. Next, heat transfer coefficients were measured in condition of constant heat fluxes. These data were compared with those in conventional tubes. The inner diameter of test tube is 0.51 mm, and the test fluid is HCFC123. Ranges of the experimental parameters are as follows: the pressure P= 0.1-0.3 MPa, the mass flux G= 150-500 kg/m^2s, the heat flux q= 10-30 kW/m^2, the vapor quality x= 0.06-1.0. The pressure drops and heat transfer coefficients were lower than those in conventional tubes.
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桃木 悟, 山田 たかし, 大河内 聡輔, 豊田 香, 茂地 徹
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Quenching experiments on the film boiling heat transfer from a vertical cylinder were performed using the cylinders with a convex hemispherical bottom surface and a flat bottom surface. The silver and stainless steel were used as the materials of the test cylinders in order to investigate also the effect of the thermal conductivity. The behaviours of vapor film near the lower limit of film boiling were observed with a high speed video camera, and the differences of the vapor film collapsing processes were investigated between the flat bottomed and hemispherically bottomed cylinders, and between the silver and stainless cylinders. The number and positions of the occasionally appeared solid-liquid contacts were also investigated using the recorded images.
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大竹 浩靖, 小林 真悟, 小泉 安郎
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The behavior of rewetting on high superheated surface, focusing on rewetting temperature during collapse of saturated film boiling was investigated experimentally. And we analyzed it in saturated and subcooled. Saturated film-boiling experiments in pool boiling were conducted by using a copper block with 20 mm length, 20 mm width and 80 mm thickness and pure water at atmospheric condition. We carried out the experiment in a steady state and a non-steady state. We rebuilt the analysis model by the previous report in consideration of influence of the subcooled liquid. Therefore we used Two-Phase Boundary Layer Treatment.
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高島 武雄
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A simulation on the vapor film thickness around a hot sphere in the subcooled film boiling under a cyclic pressure wave was carried. When the external cyclic pressure wave which has same natural frequency of vapor film applied the vapor film thickness widely changes. It is indicated that the analysis predicts the vapor film becomes instable and the vapor film collapse will occur when its thickness becomes thinner than surface roughness. If a hot sphere is a high temperature molten metal in low temperature water the vapor explosion occurs.
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杉山 均, 関矢 隆行, 加藤 直人
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Numerical analysis has been performed for turbulent flow in a HVAC (Heating, Ventilating and Air Conditioning) unit with heat transfer and sharp 90-degree turn by using an algebraic Reynolds stress and turbulent heat flux models. Besides, the other calculation has been done for temperature fields assuming turbulent Prandtl's number is constant. The calculated results suggest that both turbulent heat flux and turbulent Prandtl's number models with constant value are able to reproduce characteristic features of temperature fields.
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千葉 博, 石川 博章, 中尾 一成, 松岡 宏明
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In recent years, as heat dissipation rates in power devices are increasing, the heat sink with micro channels, which has many channels with channels diameter of several tens microns, is a promising cooling device. In this work, we both experimentally and numerically investigate the heat transfer characteristics of a grooved heat sink with micro channels consist in silicon. As a result, the heat transfer characteristics can be predicted by using the conventional analytical equation for the grooved heat sink with channels diameter of several millimeters.
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柴原 誠, 劉 秋生, 福田 勝哉
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Forced convection transient heat transfer for Carbon Dioxide at various periods of exponentially increasing heat input to a horizontal plate (ribbon) was experimentally studied. The authors measured heat flux, surface temperature, and transient heat transfer coefficients for forced convection flow of helium gas over a horizontal plate. The gas flow velocities ranged from 1 to 3 m/s, the gas temperatures ranged from 313 to 353 K, and the periods of heat generation rate, τ, ranged from 46 ms to 16 s. It was obtained that the heat transfer coefficient approaches the quasi-steady-state one for the period longer than about 1 s, and it becomes higher for the period shorter than around 1s. Empirical correlation for quasi-steady-state heat transfer was obtained based on the experimental data.
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藤本 雅則, 栩谷 吉郎
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As an electric field is applied perpendicular to the silicone oil/water interface, it is known that the instability is occurred on the interface. The behavior of the interface and flow in the oil are observed in detail by use of visualization technique, and the image photographed by a high-speed video camera is analyzed on the monitor. It is confirmed that the interfacial instability originates in electro-convective flow in oil. And the wavelength of the Taylor cone generated on the interface is also shown.
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児玉 智史, 阿部 泰時, 藤澤 史和, 山田 貴延, 中西 喜美雄
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There is a significant difference in the amount of biogas which is produced from sewage treatment process between summer and winter. Therefore, an efficient storage method is necessary for the effective utilization of biogas. The hydrate storage system using the snow is expected as an energy saving method. In the study, gas hydration was investigated as the influence of bulk density of ice layer in the formation and ambient temperature in the storage. As the results of the experiment, it was found that the optimum bulk density for the formation was 0.69g/cm^3 and the ambient temperature of 0℃ was suitable for the storage. And, it was also found that the required energy of the hydrate storage could be reduced from that of the compressed gas storage when the snow was used as a host material of hydrate formation.
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梅田 健大, フィルダウス モハマド, 山田 貴延, 中西 喜美雄
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Freezing in total heat exchanger element usually brings a serious problem on house ventilating system under cold conditions. To solve this obstacle deicing method was investigated in this study. As the results of the experiment, it was found that ice and frost attached inside the wall of the element could be melted, when the induced air from the outside and heating air were periodically exchanged. Necessary energy for heating would be remarkably small with the combination of the eco-cute, compared with the conventional methods.
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村田 圭治, 中畑 仁志, 荒賀 浩一, 小松 幸雄
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This paper is an experimental investigation on thermo chemical characteristics of corrosion reaction of iron powder. Putting iron powder, powdered active carbon, vermiculite and saline solution into mini-autoclave, its inside was replaced with oxygen, and reaction velocity was examined from the decrease in pressure. The reaction velocity depended on the temperature, the volume of saline solution, and the reaction rate of iron powder. Reaction velocity rose with temperature and saline solution in this experimental condition. In addition, authors examine the reactive characteristic in the powder layer composed of iron powder, active carbon powder and vermiculite filled with saline solution.
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竹中 宏之, 遠藤 涼平, 上野 憲史, 山田 貴延, 中西 喜美雄
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In Japan, dry batteries of about 57,000 tons are disposed every year. However, some of the waste dry batteries are recycled. Itomuka Zinc Calcine is called as IZC and it is produced from this disposal process. IZC is the calcinations powder which is mostly composed of ZnO and MnO. We have to develop the purpose because IZC is currently not needed. The particular purpose of this study is the applied research for IZC as useful materials for thermal storage, heat insulator, heat exchanger accessories, solar thermal storage and snow melting facility. In order to achieve this goal, the mixture of IZC powder with binder may be sized in pressing mold and the final dried porous material will be obtained by roasting in electric furnace. In this paper, thermodynamic properties of IZC porous material such as specific heat constant, effective thermal conductivity and spectral emissivity are especially measured.
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Mehdi Baneshi, 円山 重直, 小宮 敦樹
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Pigmented coatings with high reflectivity against solar irradiation can be used to control unwanted thermal heating. However, these surfaces produce glare that is unpleasant to the eye and can damage the appearance of the coated object. Our proposed coatings maximize the reflectivity of the near infrared (NIR) region to reduce thermal effects, while for aesthetic appeal they also minimize the visible (VIS) reflected energy. Titanium dioxide, zinc oxide and aluminum oxide are common white pigments used in coatings considered in this work. Radiative heat transfer in pigmented layer is analyzed using radiation element method by ray emission model (REM^2). The optimum values of particle size and volume fraction, film thickness and color coordinates are obtained for each pigment. Our results show that these pigments show almost the same behavior for our purpose but optimum TiO_2 pigmented coating has lower film thickness and volume fraction.
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一色 翔悟, 伊與田 浩志, 西村 伸也, 北 拓士, 河村 和彦
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Generally, the conditions of convective heating in equipments used for food processing, such as a dryer or an oven, varies slightly. For instance, in automatic regulation, door opening/closing can cause such fluctuations. In this study, the effect of flow conditions (temperature, humidity, and pressure under constant/nonconstant conditions) on the material temperature and drying rate is investigated by an experiment and a numerical study using an approximate model for heat and mass transfer. The results show that the change in the humidity of the drying media is affected strongly by the material temperature and drying rate. With in a few seconds of a decrease in the humidity, the evaporation rate increases temporarily under the experimental conditions of this study.
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辻野 智也, 井上 保, 山形 純子, 伊與田 浩志, 西村 伸也
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The behavior of condensed water on the surface of a spherical porous material by direct contact condensation in the early stage of superheated steam/high humid hot air drying was investigated experimentally. A spherical brick was used as the sample porous material. The changes in the mass and surface and core temperatures of the material during drying were measured at various dry- and wet-bulb temperatures of the drying media, and various initial moisture contents of the material. From the experimental result, it was observed that the amount of condensate increased with a decrease in the dry-bulb temperature at high wet-bulb temperature or an increase in the wet-bulb temperature. The amount of one drop of condensate decreased at high wet-bulb temperature. Furthermore, when the initial moisture content of material was slightly lower than the maximum moisture content of the material, the total amount of drops was increased.
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井上 保, 伊與田 浩志, 西村 伸也
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The effect of dry- and wet-bulb temperatures on the drying time of a wet spherical porous material in high-temperature gas flow was investigated. The changes in the mass and surface and core temperatures of the material during drying were measured using a test apparatus, in which the dry- and wet-bulb temperatures could be controlled in the range of 120-280 and 40-100 ℃, respectively. A wet spherical brick was used as the sample porous material. The experimental results showed that the mean moisture content at the end of surface evaporation period (the critical moisture content) was low under high wet-bulb temperatures. Further, the standardized drying characteristics curves for falling drying rate periods were in good agreement with each other under all experimental conditions. In addition, the time required to reduce the moisture content below the critical moisture content was almost the same under all wet-bulb conditions at the same constant drying rate, regardless of steam condensation.
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森 昌司, 奥山 邦人
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Cooking by superheated steam is receiving increased attention because it has advantages of reducing the salt and fat contents in foods as well as suppressing the oxidation of vitamin C and fat. In this application, quick startup and cut-off responses are required. Most electrically energized steam generators require a relatively long time to generate superheated steam due to the large heat capacities of the water in container and of the heater. A simple structured generator which quickly produces superheated steam was proposed in a previous paper [3]. Only a fine wire heater is contacted spirally on the inside wall in a hollow porous material. In the present paper, process of rapid generation in superheated steam using water contained porous material investigated experimentally.
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小栗 翔一郎, 名田 譲, 野田 進
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The radiation effect on NOx emission characteristics of jet nonpremixed flames in cylindrical furnaces has been investigated through a comparison of flame characteristics in steel and glass walls. The NOx emission owing to the radiation increases in steel furnaces, especially, with the inner diameter of furnace and the global equivalence ratio. This is caused by entrainment of higher-temperature burned gases into the flames and by the increase in the flame size, respectively. The increase in the inner diameter of furnace decreases the radiant fraction. However the EINOx owing to the radiation increases with the inner diameter of furnace. This might be attributable to still the enhancement of higher-temperature burned gas.
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藤本 悟, 上島 光浩
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発行日: 2008/08/02
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As a means for a stable premixed combustion, there is a so-called cyclone combustor, which consists of a cylindrical chamber and fuel nozzles installed tangentially on the side wall. In this combustor an extremely stable flame can be obtained in the swirl flow, formed along the inner wall of the combustor. The authors utilized this combustor as a flame holder, to burn a high velocity jet flowing axially in the central part, and named this new combustor a cyclone-jet combustor. In the present study, the excellent flame stability is shown for the cyclone-jet combustor and, comparing among premixed, non-premixed and partially premixed flame, the low NOx combustion characteristics was experimentally examined for this combustor.
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高橋 拓也, 川上 忠重
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下栗 大右, 白神 洋輔, 石塚 悟, 石井 一洋, 藤 秀実
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Recently, many developments have been made on the tubular flame burner for practical use. However, unexpectedly, it was found that the oscillatory combustion occurred in large size (8 and 12 -inch) tubular flame burners under some conditions. In this paper, to research the oscillatory combustion in a tubular flame burner, pressure fluctuations in the tubular flame burner have been determined, and then, FFT analysis has been made on them. Results have clearly indicated that large amplitude high frequency pressure fluctuations are preceded by intermittent 2400Hz pressure fluctuations. The frequency of 2400 Hz agrees with the natural frequency of (tangential, radial) = (1, 1) mode of 8-inch tubular flame burner. Thus, (tangential, radial) = (1, 1) mode pressure fluctuation can be considered to dominate the large amplitude, high frequency oscillations in tubular flame burners.
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三浦 大志, 古川 純一
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It has been thought that the local extinction of turbulent premixed flames occurs due to the local flame stretch. However, the local extinction of turbulent premixed flames has never been observed experimentally because the definitive experimental technique to detect the local extinction has not been established. The objective of the present study is to establish the definitive experimental technique to detect the local extinction of turbulent premixed flames by measuring emissions of intermediate species from hydrocarbon-air premixed flames. Emission intensities of OH, CH. and C_2. the major intermediate species of the hydrocarbon-air flame have been examined. It has been shown that the unique relation exists between flame temperature and the ratio of the emission intensities of the C_2 470 nm and 515 nm bands. implying that the flame temperature can be estimated by measuring the ratio of the emission intensities of the C_2 470 nm and 515 nm bands.
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藤井 真琴, 川上 忠重
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福本 一生, 大上 芳文
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The aim of our research is to build a model which can evaluate the amount of combustion products by using the chemical equilibrium method with a few chemical reactions. This paper presents a eddy dissipation concept/chemical equilibrium model (EDC/CE) and validates it by simulating CO-H_2 air turbulent diffusion flame. The obtained results were compared to the Correa's experimental data, Gran's computational data. An advantage of the EDC/CE model that any combustion products are obtained without using detailed chemical mechanisms. The results obtained by the EDC/CE model are in good agreement with these reference data. With the combustion model built in this paper, the combustion products can be calculated without detail chemical mechanisms, and the accuracy present model is in same order of the EDC model.
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名田 譲, Doniyor BAKHTIYOROV, 野田 進
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A numerical simulation of counterflow diffusion flame was conducted to investigate the effect of fuel dilution with helium and argon on NOx emission. The counterflow diffusion flame is modeled using the Opposed-Flow Flame in the CHEMKIN package. The flame stretch increases the global formation rate of EINOx whereas decreases it rapidly near the extinction condition in the laminar flame. This tendency can be observed over the entire tested range of dilutions with Ar and He. On the other hand, it was reported that the flame stretch decreases the formation rate in the high Ar-diluted turbulent flames. An estimation of scalar dissipation rate in the turbulent Ar-diluted turbulent flames reveals that the decrease in the formation rate is due to an increase in the flame stretch.
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助川 義寛, 木原 祐介, 中山 容子, 熊野 賢吾
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A combustion concept was proposed to reduce unburnt THC from gasoline direct injection engines. (1) The retarded ignition control with the split injection, the 1st injection timing is the later period of compression stroke and the 2nd one is the early period of expansion stroke was able to reduce THC up to 33% in comparison with a conventional method. (2) Combustion stability at retarded ignition was improved exceedingly by using the fuel-spray directed under the spark plug and the step-shaped piston. The fuel injected at the 1st injection timing was guided around the spark plug so stable stratified mixture was generated until 30degATDC. (3) There was no penalty at full load conditions with the proposed combustion concept, because required step height on the piston for the concept was considerably low so mixture distribution at full load condition was not affected by the piston geometry.
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柏瀬 浩司, 菊田 和重, 田部 豊, 近久 武美
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Experiment and numerical simulation indicated that the large NOx formation in diesel engine is due to the weak mixing intensity in the spray tip region, where the flow and turbulence structure is quite different from the continuous jet flames. The fact indicates that there is a possibility of reducing NOx from diesel engines by enhancing mixing intensity at the spray tip region to the level of continuous jet flame. This paper presents the analysis of NOx formation in diesel engines using HTB-DECS to confirm the effect of pre-shock jet. This analysis performed by changing the magnitude and/or timing of the turbulence that influences the air entrainment into the fuel-spray. The results show that NOx formation is greatly related in the turbulence strength. It is very important to control the timing to give the strong turbulence. Furthermore, the simulation also performed by the jet flame with/without the impinging jet using FLUENT. The large NOx reduction was able to be confirmed in the case with the impinging jet.
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森田 真一, 渡辺 直樹, 斉藤 正浩, 古畑 朋彦, 新井 雅隆
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Six-stroke diesel engine proposed here has six processes in one cycle, i.e. intake, 1st compression, 1st combustion, 2nd compression, 2nd combustion and exhaust. By the direct EGR in the 2nd combustion process, NO emission could be expected to decrease. However, much soot was exhausted by a weak mixing in the 2nd combustion process. A high pressure injection with a common rail was introduced into the engine to improve the mixing in the second combustion process. As the result, more NO was exhausted while soot was decreased due to well mixing. In this study to decrease NO and soot simultaneously, two stage injection was applied to the engine. In the case of conventional combustion with pilot injection, NO and soot were decreased. When the main injection timing in 1st combustion was delayed extremely to control the 1st combustion process, NO and soot were more decreased compared with the case of conventional combustion with pilot injection.
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小保方 優介, 根本 直也, 斉藤 正浩, 古畑 朋彦, 新井 雅隆
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発行日: 2008/08/02
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Effects of gas flow rate and initial NO concentration on NO removal using a dielectric barrier discharge were investigated experimentally. When the initial NO concentration was high, the DeNO_x performance was deteriorated. Moreover, DeNO_x performance became low with increasing gas flow rate. Then effect of O_2 concentration on NO removal using a dielectric barrier discharge was investigated experimentally. N_2/NO/O_2 mixture was used as the test gas. The O_2 concentration was changed from 0% to 20%. In the case of nitorgen atmosphere(O_2=0%), NO was mainly removed by N radical. On the other hand, in the case of exsiting O_2, NO removal mechanism was controlled by the concentration of ozone, which formed from O_2 with barrier discharge.
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岸 武行, 平田 宏一, 西尾 澄人, 福田 哲吾, 永井 建夫
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Land-use SCR NOx removal systems were investigated for its application to marine diesel engines. A micro-reactor was used to acquire the base data of land-use SCR NOx removal catalysts, and the data were formulated in regard to temperature and geometry of catalysts for design of practical NOx removal system for marine engines. Also, NOx removal tests of the land-use catalyst using exhaust gas from a practical marine diesel engine were performed, and the performance was roughly as expected.
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徐 芝徳, 古堅 宗勝, 牧野 義, 塚本 達郎
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In this research, an Electrostatic-cyclone DPF (Diesel Particulate Filter) was developed to reduce the PM (Particulate Matter) emission from marine diesel engines. Experiments were executed to investigate the effect of the exhaust gas temperature in the DPF inlet on the PM collection efficiency. The results show that the DPF is suitable for the marine diesel engine, and the collection efficiency of PM is high; 65% estimated by dilution method and 85% by opacity smoke-meter, and that the exhaust gas temperature has little effect on the collection efficiency.
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飯島 直樹, 中村 公胤, 小林 優介, 瀧口 雅章
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セッションID: 2307
発行日: 2008/08/02
公開日: 2017/08/01
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This study was aimed at reduction of piston friction losses in supercharged gasoline engine. The floating liner device was improved to measure piston friction forces on supercharged condition. Effects of piston friction forces on skirt clearance, skirt overlap, and skirt roughness were verified from measured results of piston friction forces. As a result, Piston friction losses increased with the increase in engine load, and the increase in fiction losses strongly depended on the amount of overlap in piston skirt. And piston friction losses on high load condition greatly reduced by larger piston skirt clearance and smaller skirt roughness.
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末 誠一, 河野 佳介
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セッションID: 2308
発行日: 2008/08/02
公開日: 2017/08/01
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This study was aimed at clarifying the effects of piston pin offset on the piston friction at Crank-offset engine. We measured the Piston Friction reduction and the oil film behavior between skirt and cylinder bore, and analysis of these results in detail, We calculated piston secondary motion used by CAE tool. In order to effective reduction of Piston Skirt Friction at Crank-offset engine, We paid attention of Anti thrust side skirt contact condition at early combustion stroke.
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副島 光洋, 松下 祐樹, 坂口 慎吾
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セッションID: 2309
発行日: 2008/08/02
公開日: 2017/08/01
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For the valve train with camshafts and roller followers, influences of the roller support bearing and the engine oil property on the friction losses at the contact between cam and roller follower and the contacts of other elements in the valve train were examined by measuring the contact load and the friction force between the cam and the roller follower with a practical sized OHV valve train friction tester. The followings were made obvious. (1) The friction loss is smaller with the roller support of slide bearing than that of needle bearing. (2) When the viscosity of low-SAPS engine oils becomes low, the friction between cam and roller hardly changes but that from the other valve train elements slightly increases. (3) The friction loss is smaller with engine oils lower in sulfur content than DH-2 class engine oils.
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浜武 俊朗
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セッションID: 2310
発行日: 2008/08/02
公開日: 2017/08/01
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The theoretical analysis on the mixed lubrication of asymmetric compression rings in a 4-stroke cycle diesel engine is made. The analysis comprises Patir and Cheng's average flow model and Lee and Ren's asperity interaction model. Effects of asymmetric rings with different barrel height and/or off-centered profile on the film and friction characteristics are investigated. The friction characteristics are remarkably affected by the barrel height and offset.
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古平 真一郎, 針谷 安男, 鈴木 道義, 飯島 直樹, 瀧口 雅章, 吉田 秀樹
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セッションID: 2311
発行日: 2008/08/02
公開日: 2017/08/01
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For the solution of energy and environment, the reduction of the lubrication oil consumption (LOC) and the friction work at ring of the internal combustion engine is very important. In this paper, effect of the oil film thickness on LOC was estimated by using an unsteady and one-dimensional thermal conduction equation. Also, the calculated result and the measured value for LOC were compared. The evaporation oil was affected by oil film thickness. The evaporated oil on the liner wall changes more greatly during the combustion and expansion strokes. The evaporated oil per one cycle increases with increasing oil film thickness.
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酒井 靖志, 鈴木 隆雅, 吉田 秀樹
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セッションID: 2312
発行日: 2008/08/02
公開日: 2017/08/01
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Sliding evaluation of some surface modified piston rings for aluminum (A390) cylinder was conducted using a reciprocating wear tester. Large amount of wear including abnormal wear has been observed on the cylinder surfaces in combination with piston rings with Cr containing surface modifications, i.e., Cr plating, ion plated CrN, and nitriding of martensitic stainless steel with high Cr content. It has also been observed in sliding with nitrided piston rings that the cylinder wear is increased with Cr content of ring material. On the contrary, DLC (Diamond Like Carbon) coated piston ring has shown superior anti-wear performance (no damage for cylinder) for the aluminum cylinder.
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吉川 航, 福島 鷹朗, 石井 一洋
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セッションID: 2313
発行日: 2008/08/02
公開日: 2017/08/01
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In order to clarify spark ignition mechanism by multiple spark discharge, the effects of spark interval on ignition probability have been experimentally studied using two successive sparks with spark interval of 100 ms to 600 ms. The experimental results show that the ignition probability monotonically decreases with increase in the spark interval. From the fact that the breakdown voltage of the second spark discharge in the case of the extinction is higher that that in the successful ignition, the formation of the spark channel by the second spark discharge is related to the successful ignition.
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勝俣 雅人, 三谷 将弘, 渡辺 雄介, 森川 弘二, 桑原 卓雄, 田辺 光昭
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セッションID: 2314
発行日: 2008/08/02
公開日: 2017/08/01
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Improvement on thermal efficiency in spark ignition engines requires high compression ratio, lean burn, reduction of cooling loss and soon. High compression ratio is the most promising way to improve the thermal efficiency, while engine knock becomes critical problem. High-speed Knocking is difficult to test since it gives mechanical damages to the engines. Therefore, generation mechanism and the method of knocking suppression have not been well clarified. To research the mechanism at the high compression ratios and the high engine speeds, a Super Rapid Compression Machine (SRCM) was developed. By this SRCM, a sudden expansion of end-gas was detected at the beginning of the high-speed knocking occurrence, that indicates a certain heat release before hot flame appearance.
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村澤 裕樹, 洪 闖, 手崎 衆
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セッションID: 2315
発行日: 2008/08/02
公開日: 2017/08/01
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Behavior of intermediate species transiently formed in low temperature oxidation is a key to better understanding and control of compression ignition. In this study, we have applied a method of time resolved direct sampling from cylinder to detect such species in a test engine operated at HCCI mode with nOheptane as the fuel. It was observed that partial consumption of n-heptane and HCHO formation take place simultaneously, and the extent of these consumption and formation were in good agreement with predicted by the detailed chemical mechanism for oxidation of primary reference fuel proposed by Curran et al. In addition, experimental profiles of these species were also reasonably coincided with the simulation, when the timescale of the zero dimensional calculation was corrected for the heat release profiles to the experiment.
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須藤 賢志, 大原 智彦, 山崎 博司, 野村 浩司, 氏家 康成, 石井 一洋
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セッションID: 2316
発行日: 2008/08/02
公開日: 2017/08/01
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Experimental and numerical researches have been performed to obtain the detailed information about the ignition and combustion characteristics of flanged electrodes in premixed gaseous flow fields. Cylindrical type, and flange combined both cylindrical and disl type were mounted on the tips of comventional electrodes. It was mainly investigated that the effect of the flanges exerted on ignition energy reduction and flow velocity reduction between the flanges in a swirling flow field with propane-air mixure. We obtained results that the minimum primary current decreases in a quiescent and wide range of swirling flow velocity, and that the flow velocity at the center of electrodes decreases. The degree of reduction effects depend on flange shape.
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清水 貴之, 坂田 祐一, 山名 康介, 西田 憲二, 荒木 幹也, 中村 壽雄, 志賀 聖一, 小保方 富夫
原稿種別: 本文
セッションID: 2317
発行日: 2008/08/02
公開日: 2017/08/01
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This study presents the possibility of realizing better thermal efficiency in a spark-ignition engine with over-expansion cycle. The test engine with the displacement volume of 649cc was used together with four kinds of expansion ratios (geometric compression ratio) from 10 to 25, and four sets of intake valve closure timings from 0 to 110 deg. C.A. ABDC. In previous studies, the indicated thermal efficiency reached 48%. However, there was a problem that the maximum output was reduced to almost half compared with the conventional engine, since the effective displacement volume was decreased with decreasing the substantial compression ratio (E c). As a method of solving this problem, supercharging was applied by using compressed air supplied from an external compressor. As a result, BMEP could be vastly expanded under most conditions, and the BSFC could be improved by about 22% at the maximum comparing with the original condition the compression ratio of 10 with the intake valve closure timing of Odeg. C.A. ABDC
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末岡 大佑, 菊池 孝之, 野村 浩司, 氏家 康成
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セッションID: 2318
発行日: 2008/08/02
公開日: 2017/08/01
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In order to make a lean burn successful, it has been an important subject to from ignition certainly with small spark energy. In this research, consequently, aiming at realization of this subject, a flange was installed in a conventional spark plug for the purpose of recovery of the shock wave energy generated at the time of spark discharged, and flow control of fuel-air mixture. Using a natural gas engine equipped with the flanged spark plug, the improvement effect of the ignition characteristic was confirmed. Additionally, effects of the flange shape on the ignition and combustion characteristics were compared and discussed.
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竹内 俊輔, 飯島 晃良, 庄司 秀夫, 吉田 幸司
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セッションID: 2319
発行日: 2008/08/02
公開日: 2017/08/01
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A new combustion method which is using the characteristic of plasma jet ignition is proposed. This new combustion method has feature of diffusive combustion, however the fuel is injected and ignited by the high-voltage electrical discharge. When the cavity of plasma jet igniter is filled with liquid fuel, the fuel plasma jet spreads into combustion chamber and is mixed with air in combustion chamber, and then the diffusive combustion occurs. Tests are carried out with four kinds of fuel by using a constant volume vessel. All kinds of fuel are surely injected by the electrical discharge and are certainly ignited and burned by this combustion method. The diffusion flame development process is influenced by fuel properties. Iso-octane is surly ignited, however, diffusion flame does not grow enough. When the small orifice is used, the diffusion flame rapidly spreads, however, the combustion pressure increases as the orifice diameter increases.
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洪 闖, 村澤 裕樹, 手崎 衆
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セッションID: 2320
発行日: 2008/08/02
公開日: 2017/08/01
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Intermediate species, which are formed in the cool ignition stage of autoignition, were evaluated by exhaust gas analysis with FT IR on hot ignition suppressed conditions in a test engine with PRF as the fuel. In addition to HCHO, HCOOH, CO and CO_2, which were detected in our previous study using DME as a fuel, formation of iC_4H_8, C_2H_4 and CH_3OH was confirmed newly. Trends in formation of these species against fuel composition and equivalence ratio were in qualitative agreement with predicted by the detailed reaction mechanism for PRF oxidation. The iC_4H_8 formation is specific to iC_8H_<18> in the composition of PRF, indicating a strong tendency toward β-scission of iC_8H_<17> radical, whereas nC_7H_<15> radical tends to take multiple O_2 additions. These tendencies correspond to the difference in ignition property of these PRF components.
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山崎 祥史, 片山 泰貴, 飯島 晃良, 庄司 秀夫
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セッションID: 2321
発行日: 2008/08/02
公開日: 2017/08/01
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Homogeneous Charge Compression Ignition (HCCI) combustion has attracted considerable interest in recent years as a new combustion concept for internal combustion engines. The HCCI combustion process has four issues to be resolved: ignition timing control, slower combustion reaction rate (maximum heat release rate), difficulty expanding stable operation to the high load region and avoidance of knocking. In this study, an attempt was made to overcome these issues by mixture stratification. This stratification combustion has such a concept.: the density of the air-fuel mixture is uniform, the ignition characteristic is different in the cylinder. The experimental result that ignition occurred locally at the low octane side then occurred high octane side in the cylinder. As the result, the combustion reaction speed can be slower and avoidance of knocking without using EGR.
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