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Tetsuya AIZAWA, Hidenori KOSAKA, Yukio MATSUI
Article type: Article
Pages
95-96
Published: September 20, 2002
Released on J-STAGE: August 01, 2017
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In order to investigate the soot formation process in a diesel spray flame, simultaneous imaging of soot precursor and soot particles in a transient spray flame achieved in a rapid compression machine was conducted by laser-induced fluorescence (LIF) and incandescence (LII) techniques. The LIF due to soot precursor and the LII due to soot particles were separately imaged by two image-intensified CCD cameras with identical detection wavelength of 400nm and bandwidth of 80nm. The LIF due to soot precursor was mainly located in the central region of the spray flame between 40 and 55mm downstream from the nozzle orifice. The LII due to soot particles was observed to surround the soot precursor LIF region and to extend downstream. First appearance of the LIF due to soot precursor in the spray flame preceded the appearance of the LII due to soot particles. The intensity of the LIF due to soot precursor reached its maximum immediately after rich premixed combustion. In contrast, the intensity of the LII due to soot particles increased gradually and reached its maximum after the end of injection. Measured LIF spectrum of the soot precursor in the spray flame was very broad and showed no apparent spectral structure.
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Hiroyuki Hirano, SungSub Kee, Ai Mohammadi, Kei Miwa
Article type: Article
Pages
97-98
Published: September 20, 2002
Released on J-STAGE: August 01, 2017
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Chemical behaviors of diesel fuel and the effects of aromatic on diesel combustion were experimentally investigated using a rapid compression machine and a total gas-sampling device. Aromatic component was varied independently as fuel property while keeping the cetane number and sulfur content. The authors analyzed the composition of the individual hydrocarbons (C_1 to C_<20>), NO_x and inorganic gases. The results show that the concentration of heavy hydrocarbons rapidly decreases during ignition delay period due to thermal cracking into middle and low boiling-point hydrocarbons. However, the fuel including aromatic is decomposed with difficulty because of the lower decomposition rate of not only aromatic component but also other heavy saturate hydrocarbons, which causes the high concentration of middle boiling-point hydrocarbons at diffusion combustion period and late oxidation. NO_x concentration also proceeds later at the end of combustion and reaches higher level than in aliphatic hydrocarbon fuel.
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Naoto KITAYAMA, Hideyuki TSUNEMOTO, Hiromi ISHITANI
Article type: Article
Pages
99-100
Published: September 20, 2002
Released on J-STAGE: August 01, 2017
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Throttling of intake and exhaust ports in DI diesel engines are often used to get high EGR rate and to rise exhaust gas temperature at light load. However, cylinder-to-cylinder deviations in the combustion and the exhaust emission are not clear during the throttling process. This study attempts to investigate correlations between cylinder-to-cylinder deviations in the fuel injection characteristics and combustion and THC emission when intake and exhaust ports are throttled at idling. It is concluded that cylinder-to-cylinder deviations in THC emissions are larger at intake port throttling, but is not significant at exhaust port throttling. Cylinder-to-cylinder deviation in combustion is responsible for the deviations in THC but that is not dominating factor. Deviations in the in-cylinder conditions such as carbon deposits and in-cylinder gas flow are thought to play a larger role in THC deviations.
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Tetsuya TAGAI, Masahiro ISHIDA, Daisuke FUCHIGAMI, Hironobu UEKI
Article type: Article
Pages
101-102
Published: September 20, 2002
Released on J-STAGE: August 01, 2017
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In order to attain a significant improvement of the trade-off between NOx and smoke, combustion tests on methanol premixture were carried out in a dual-fueled diesel engine assisted by gas oil injection The effects of methanol mixture concentration, intake temperature and the EGR rate on ignition and combustion of methanol premixture were investigated respectively as well as the effects of gas oil injection timing and nozzle orifice size on smoke and NOx. It is clarified that it is necessary to control the intake temperature for avoiding the auto-ignition of methanol mixture, and the suitable combination between methanol charge rate, gas oil injection timing, nozzle orifice size, intake temperature and EGR rate is required for each load to obtain a marked improvement of the trade-off.
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Takashi Matsuura, Michihiro Ohnuma, Seiichi Shiga, Kazumitsu Kobayashi ...
Article type: Article
Pages
103-104
Published: September 20, 2002
Released on J-STAGE: August 01, 2017
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This paper presents a study on the effect of injection rate on the performance and emissions in a direct-injection gasoline engine. Five kinds of swirl injectors were utilized with the static injection rate of 600,700,800,900 and 1000cc/min at an injection pressure of 7MPa. The BSFC is shown to have its optimum at aninjection rate. The BSFC variation is attributable to the combustion efficiency variation due to the behavior of droplet concentration of the fuel spray. The effect of the static injection rates was not recognized in both mechanical efficiency, and cycle efficiency.
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Tatsuya KUBOYAMA, Hidenori KOSAKA, Yukio MATSUI
Article type: Article
Pages
105-106
Published: September 20, 2002
Released on J-STAGE: August 01, 2017
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To investigate the effect of impinging flame characteristics on heat transfer between the flame and the chamber wall, total heat loss was measured using a rapid compression expansion machine. Experimental results using nozzles with smaller and more orifices showed reduced combustion efficiency and heat loss fraction. However, significant effects on thermal efficiency were not observed.
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Hiroyuki OONISHI, Hideyuki TSUNEMOTO, Hiromi ISHITANI
Article type: Article
Pages
107-108
Published: September 20, 2002
Released on J-STAGE: August 01, 2017
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The improvement of exhaust emissions in diesel engines will be achieved by combustion improvement and after-treatment. The exhaust catalyst is one of after-treatment and recently this system is adopted on passenger cars and trucks. But the exhaust gas temperature in diesel engines at idling condition is about 100℃, and doesn't reach the condition to active the catalyst. In this study, we attempted to increase the exhaust gas temperature by controlling of intake and exhaust systems and operating cylinder numbers. As a result, the exhaust gas temperature at idling condition could approach about 300℃ by applying the intake throttling and a half cylinder operation.
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Eiji TOMITA, Nobuyuki KAWAHARA, Yamato NAKAMIZO
Article type: Article
Pages
109-110
Published: September 20, 2002
Released on J-STAGE: August 01, 2017
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It is a problem that unburned hydrocarbons are exhausted at cold start in spark-ignition engines. In this study, an infrared absorption method was applied to in-situ measurement of hydrocarbon concentration. A He-Ne laser was used as an incident light and reflected three times in the exhaust pipe to make the measurement length long enough to determine the HC. AS a result, misfire is detected without fail. It was found that the HC concentration has a relation to indicated mean effective pressure. In late ignition timing, the temperature of the exhaust gas increases and the HC concentration decreases while the cycle-to-cycle fluctuation of mean effective pressure increases. When the fluctuation is large, the HC is larger in the cycle of lower mean effective pressure and the HC is smaller higher one.
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Hiromichi NOSAKA, Naoki Hiramatsu, Kinji Tsujimura, Katsuhiko Yokota
Article type: Article
Pages
111-112
Published: September 20, 2002
Released on J-STAGE: August 01, 2017
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In recent years, the exhaust gas of a diesel engine is a serious environmental problem. Especially NOx in the exhaust is a very toxic substance, and it is very difficult to decrease NOx by combustion modification. Also, an effective emission reduction device like 3way catalyst of a gasoline engine is very difficult to develop for diesel engines. Therefore, the method of NOx removal is studied by an electric discharge which does not need any reducing agent and high temperature.
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Katsunori YOGO, Masamichi ISHIKAWA, Kenji OOE, Tatsuro TSUKAMOTO
Article type: Article
Pages
113-114
Published: September 20, 2002
Released on J-STAGE: August 01, 2017
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New purification technology of the nitrogen oxide discharged from vessels, such as a small coaster, was developed. A new de-NOx system by the combination of an "adsorbent-selective reduction catalyst" was studied as a method of solving the problem that a former type SCR catalyst does not fully operate on the conditions that the exhaust gas temperature is low (below 300℃). Mn-Zr oxide was effective in removing NO at 100-300℃ by absorption in the solid as nitrate. Nitrogen oxides were first stored in the Mn-Zr oxide below 300℃. Then, the stored NOx was released above 300℃ and reduced by the SCR catalyst in the down-stream. As a result of the purification examination using marine diesel engine exhaust gas, it was found that 80% of NOx discharged in a low-temperature region was removable by this system.
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Wakako SAHASHI, Kyong Oh Kim, Akihiko AZETSU
Article type: Article
Pages
115-116
Published: September 20, 2002
Released on J-STAGE: August 01, 2017
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Ignition conditions of homogeneous charge compression ignition engine operated on Dimethyl Ether were investigated with focus on temperature and pressure at ignition. The compression ignition of Dimethyl Ether has two stages of combustion, which were known as cool and hot flame respectively. The ignition conditions of both stages have significant effect on the control of a HCCI engine. In this paper, the ignition conditions of cool flame were examined for two modified single-cylinder engines of different compression ratio (ε=8.1 and 18.0 respectively) to clarify the effect of compression history on ignition temperatures. Chemical kinetic computation was also performed to confirm the findings from experiment. The ignition temperature of cool flame was definitely dependent on engine speed and compression ratio, and therefore the ignition conditions of both stages of combustion should not be regarded as unique like the use of a specific temperature in the criterion of ignition in a homogeneous computation.
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Hiroyuki YAMADA, Kotaro SUZAKI, Atsumu TEZAKI
Article type: Article
Pages
117-118
Published: September 20, 2002
Released on J-STAGE: August 01, 2017
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Oxidation of dimethyl ether (DME) has been studied in motored internal combustion engine compression cycles. By applying a quadrupole mass spectrometer to monitor the exhaust gas composition, it was found that fuel consumption is limited at relatively constant extent in certain ranges of intake gas temperature and fuel-air ratio of the low temperature oxidation (LTO) regime, which is in good agreement with simulations using Curran's kinetic mechanism. It is suggested that inhibition of chain branching by piled up HCHO is responsible for this behavior. The features appeared in experiment and calculation can be explained by simplified LTO of DME and HCHO oxidation.
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Hideki SAKANASHI, Namil CHOI, Atsumu TEZAKI
Article type: Article
Pages
119-120
Published: September 20, 2002
Released on J-STAGE: August 01, 2017
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Two-stage auto-ignition in homogeneously charged compression of dimethyl ether (DME)-air mixture has been investigated using an externally motored single cylinder piston engine. Laser-induced fluorescence (LIF) measurement was conducted in situ to detect formaldehyde (HCHO) and its LIF intensity profiles as a function of crank angle were obtained in the ignition processes of the research engine. In order to quantify the quenching effects on the measured LIF signal, fluorescence Lifetime was evaluated as a function of crank angle. The obtained results were compared to the simulation using the detailed DME oxidation mechanism of Curran et al. (2000).
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Tadashi TSURUSHIMA, Yuzo AOYAGI
Article type: Article
Pages
121-122
Published: September 20, 2002
Released on J-STAGE: August 01, 2017
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Gas sampling analysis of compression ignition combustion processes in stoichiometric and rich mixtures were conducted to study the differences in histories of intermediates at around the critical equivalence ratio for smoke emission. The results showed that low temperature oxidation processes before second heat release in fuel rich conditions were the same as that in lean or stoichiometric conditions. The results also showed that carbon monoxide, hydrogen, methane and acetylene was produced after second heat release in fuel rich conditions, and benzene could be seen in higher equivalence ratio than the critical equivalence ratio for smoke emission. Benzene concentration kept increasing after heat release, which corresponded to the decrease of acetylene. Then the critical equivalence ratio seems to have a relationship with the formation limit of benzene, which supposed to be the core of soot precursor PAH.
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Yuichi OHTERU, Tetsunori SUZUOKI, Makoto KOIKE
Article type: Article
Pages
123-124
Published: September 20, 2002
Released on J-STAGE: August 01, 2017
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Effect of equivalence ratio on knocking in homogeneous spark ignition engines was investigated by using a single cylinder engine. Knocking was evaluated by an index of the degree of constant volume, which showed how close to the ideal Otto cycle the tested cycle was. Petrol but also n-butane, iso-octane and toluene were tested. The maximum tendency to knock around the stoichiometric mixture was confirmed on the condition of the same manifold pressure. However, further experimental work indicated that the maximum tendency to knock shifted from the stoichiometric mixture to the lean mixture if the charge fuel was constant.
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Yasuo MORIYOSHI, Masahide TAKAGI, Xiao HU
Article type: Article
Pages
125-126
Published: September 20, 2002
Released on J-STAGE: August 01, 2017
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Numerical analyses by DDM (Discrete Droplet Model) are carried out to clarify the effect of initial conditions on the fuel spray formation process using a swirl-type injector. Two kinds of initial conditions are tested; one is empirical expressions and the other is the results obtained using VOF model that is used to simulate the two-phase flow inside the injector to give the liquid film formation process outside the nozzle.
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Yasuhiro Shutoh, Akihiko AZETSU
Article type: Article
Pages
127-128
Published: September 20, 2002
Released on J-STAGE: August 01, 2017
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In this study, we have examined the effect of in-cylinder flow on the formation of stratified charge. To make a stratified charge, we used a 4-valve optical engine with two intake ports. The air with oil mists was supplied through two intake ports with different flow rates and mist concentrations. A cross-correlation PIV technique was applied to measure in-cylinder flow. From the measurement of tracer concentration and in-cylinder flow, it was made clear that the swirling flow and the spatial variation of air flow played an important role in the charge homogeneity.
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Chengjun XU, Seiichi SHIGA, Hisao NAKAMURA, Tsuneaki ISHIMA, Tomio OBO ...
Article type: Article
Pages
129-130
Published: September 20, 2002
Released on J-STAGE: August 01, 2017
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An experimental study was conducted conducted to investigate the feasibility of promoting the atomization of a high-speed liquid jet with wall impingement. It was shown that at a certain condition only 1/8 of the injection pressure as much as that of free spray was required to realize the same level of SMD, and thus wall impingement can remarkably promote atomization. The impingement parameters such as the area of the wall and the angle of impingement were also examined and discussed.
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Masahisa YAMAKAWA, Daisuke TAKAKI, Yuyin ZHANG, Keiya NISHIDA
Article type: Article
Pages
131-132
Published: September 20, 2002
Released on J-STAGE: August 01, 2017
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A dual-wavelength laser absorption-scattering (LAS) technique was developed to analyze the mixture formation process in a D.I. gasoline spray. P-xylene was used as a test fuel and the second harmonic (532nm) and the fourth harmonic (266nm) of an Nd : YAG laser were simultaneously illuminated the spray, which was injected into a high temperature and high pressure constant volume vessel. The dual-wave length LAS images were acquired by two CCD cameras and processed by a computer. The distribution of droplets and vapor concentrations in a D.I. gasoline spray were quantitatively analyzed.
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Tasuku YANAGIMOTO, Kazuhiro MORI, Makoto IWAMURO, Jiro SENDA, Hajime F ...
Article type: Article
Pages
133-134
Published: September 20, 2002
Released on J-STAGE: August 01, 2017
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In mixture formation process relevant to combustion and harmful matter formation process in a DI diesel engine, the turbulence effect appears from the start of break up of fuel droplets to ignitable mixture formation process. In this study, to clarify the effect of turbulence on mixture formation process, Particle Image Velocimetry (PIV) was applied to fuel droplets for investigation of the droplets behavior. The experimental results show that : Near the spray axis, droplets velocity is the fastest, and droplets in the spray peripherally have low velocity components with various directions. Fuel droplets in spray axis are disturbed by the interaction of vortex exists in spray peripherally, then this effect cause heterogeneity of fuel spray stricture, After wall impingement, fuel droplet was dispersed by turbulence effect. And dispersion of fuel droplet with high turbulence promotes fuel vapor formation.
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Tetsuya ODA, Shinya FUJIWARA
Article type: Article
Pages
135-136
Published: September 20, 2002
Released on J-STAGE: August 01, 2017
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An experimental study was conducted to examine the performance of a plain-orifice, internal mixing atomizer that was designed to produce atomization by cavitation in the orifice. The modified liquid fuel employed was water and the cavitating liquid was ethanol, which was injected into the water at the upstream of the orifice from an internal nozzle. Changes in the flow rate of ethanol and the mixing length, which is the distance between the entrance of the orifice and the exit of the internal nozzle, have little effect on the breakup length of liquid column for the cross flow type internal nozzle. The breakup length and Sauter mean diameter (SMD) decrease with an increasing in the flow rate of ethanol for the axial flow type internal nozzle while using small amounts of ethanol. A decrease in SMD occurs with a decrease in the mixing length.
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Yasuhiro MARUYAMA, Masahiro SAITO, Masataka ARAI
Article type: Article
Pages
137-138
Published: September 20, 2002
Released on J-STAGE: August 01, 2017
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To investigate the mutual interaction between plural diesel sprays impinged on a wall, two diesel sprays which were closely spaced, were impinged vertically to the flat wall. The phenomena after the impingement was observed. Spray shapes after the wall impingement were measured from sequential photographs taken by a high-speed drum camera. It became obvious that a swelled spray was newly formed by the mutual interaction of two sprays after the wall impingement. Spray shape was strongly deformed at the interaction position and was affected by the spacing between two nozzles.
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Toyohiro HAMASAKI, Hiroshi NOMURA, Yasushige UJIIE, Junichi SATO
Article type: Article
Pages
139-140
Published: September 20, 2002
Released on J-STAGE: August 01, 2017
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Fundamental studies on spray combustion have been performed using a static homogeneous fuel spray as a simple model of a real spray. Homogenous sprays were generated by the condensation method using rapid expansion of saturated ethanol vapor-air mixtures. In this study, microgravity conditions have been employed to prevent large droplet from sedimentation. Flame speed and maximum burning pressure were measured with a constant volume combustion chamber. Initial Pressure was 0.2 MPa for all experiments. The mean droplet diameter was varied from 3 to 48 μm. It was found that the flame speed and the maximum burning pressure of homogeneous sprays are larger than those of premixtures of the same equivalence ratio under certain conditions. The dependences of the flame speed and the maximum burning pressure on the mean droplet diameter are strongly affected by the total equivalence ratio.
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Makoto NAGAOKA, Toshio YAMADA, Junichi KAKO
Article type: Article
Pages
141-142
Published: September 20, 2002
Released on J-STAGE: August 01, 2017
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A conventional CFD calculation with a single shot of fuel injection cannot represent fuel behaviors in a port-injection engine because fuel is accumulated in an intake port through passed cycles. However, the multi-cycle calculation using 3D CFD is not practical because of the confounded long computational time. Supposed cyclic invariance of the gas flow field at an engine cycle steady state, a new calculation method is developed using one way coupling from air to fuel after second engine cycle. The computational time per cycle is reduced to one-tenth of conventional method by the proposed method.
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Naohiro YOSHIDA, Masaru SORA, Jiro SENDA, Hajime FUJIMOTO
Article type: Article
Pages
143-144
Published: September 20, 2002
Released on J-STAGE: August 01, 2017
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Combined combustion of premixed gas and droplets occurs in the spray combustion. The combustion of this case is the very complicated phenomenon and has not well-clarified. Therefore, in order to investigate the mechanism of combined combustion of premixed gas and droplets, experiment was carried out using a constant volume chamber with an ultra sonic vibrator with a bolted langevin transducer, and an instrument for the formation of premixed mixture for imitating the combined field of premixed gas and droplets. As a result of this experiment, the influence of the change in equivalence ratio of premixed gas, the proportion of liquid fuels and the variety of fuels on combustion were clarified.
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Hideki OKITA, Masataka ARAI, Kenji AMAGAI
Article type: Article
Pages
145-146
Published: September 20, 2002
Released on J-STAGE: August 01, 2017
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Ignition and combustion characteristics of diesel spray impinging on a wall were investigated. Delay time of firstly observed luminous flame and its appearance position were measured. Distance from nozzle tip to impingement wall were fixed at 50mm and ambient temperature was varied from 400 to 500℃. As the result, when the delay time became short (<3ms), the luminous flame appeared around the axis of fuel jet. On the other hand, when the delay time became long (>3ms), the luminous flame appeared near the impingement wall. The result showed that the luminous sooty flame was generated inside the spray with high fuel concentration.
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Daisuke Tanaka, Hajime Ishi, Yuichi Goto, Jin Kusaka, Yasuhiro Daisho
Article type: Article
Pages
147-148
Published: September 20, 2002
Released on J-STAGE: August 01, 2017
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To improve the accuracy of the numerical fuel spray dynamics, Reitz's wave break-up model has been modified by Wakisaka et al. (MWB2), and incorporated into their GTT code. Both GTT and KIVA codes utilize the Discrete Droplet Model (DDM) for the fuel droplet dynamics, So we employed MWB2 in KIVA-3. This model was verified by comparing the calculated and experimental results at various pressures and temperatures in a constant volume vessel. The predicted tip penetration and SMD show good agreement with the measurements.
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Hiroshi TOKITOU, Tomio OBOKATA, Seiichi SHIGA, Kiyohira AOKI, Takahiro ...
Article type: Article
Pages
149-150
Published: September 20, 2002
Released on J-STAGE: August 01, 2017
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In order to reveal the basic aspect of development and mixing behavior of an intermittent gas jet, an experimental and analytical study was conducted. A Rayleigh scattering technique using a KrF excimer laser was used to determine the fuel distribution of an intermittent methane gas jet injected into an atmosphere. The concentration distribution obtained experimentally was compared with the simulation results in order to evaluate the validity of the simulation, which may possibly be applied to a gas engine combustion study.
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Hidekazu TAKIZAWA, Yuta SAWAHATA, Atsushi MATSUGUCHI, Noboru KAGAWA, S ...
Article type: Article
Pages
151-152
Published: September 20, 2002
Released on J-STAGE: August 01, 2017
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A regenerator matrix was proposed and developed based on perfectly new concepts. It is a stacked mesh sheet type. Each thin stainless-steel mesh sheet has small rectangle holes and narrow and shallow grooves which connect holes on the sheet surface. These geometrical shapes are designed freely. Two types of the mesh sheet were designed and manufactured for this study. Each matrix was eqquiped with a NS03T engine and the performance was measured by using an engine test stand. The geometry and performance of the mesh sheet matrixes were compared with conventional wire mesh in detail. One of the new matrixes improved the engine output power and total efficiency remarkably. This paper introduces the experimental results of the new matrix.
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Yoshihiko HARAMURA
Article type: Article
Pages
153-154
Published: September 20, 2002
Released on J-STAGE: August 01, 2017
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This study deals with the thermodynamic design of Stirling engine. It is selected as the optimum condition that the net output power of the engine takes the maximum with respect to the variation of parameters, such as phase angle, the amount of heat storage material, rotating speed, tube or wire diameter of heat exchangers, the free-flow area of heat exchangers of the volume of heat exchangers. The net output is calculated from indicated power of multi-element simulation in which flow resistance is neglected, subtracting friction power loss calculated from existing correlations. The comparison with an existing engine has revealed that it is possible to improve engines, especially on the amount of heat storage material.
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Koichi HIRATA
Article type: Article
Pages
155-156
Published: September 20, 2002
Released on J-STAGE: August 01, 2017
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In order to develop a compact and low cost Stirling engine, an experimental Stirling engine which has simple heat exchangers and a Rhombic mechanism has been developed. Its target shaft power is 50 W at the engine speed 400 rpm and the mean pressure. 0.8 MPa using helium as the working gas. This paper describes the outline of the prototype engine and the performance test. Based on the performance, which has not reached the target performance at all, we discuss the difficulties to develop compact, low cost and high performance Stirling engines.
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Fujio TODA, Katsuaki NAKAJIMA, Shoichi IWAMOTO
Article type: Article
Pages
157-158
Published: September 20, 2002
Released on J-STAGE: August 01, 2017
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The educational Stirling engine is the simple structure, and it is utilized, as research theme and processing practical training of the high school, as a thermodynamics teaching material of technical college and university, because moreover, it is easily designed and can be produced. The Ross yoke drive mechanism exhibits certain characteristics that make it interesting to obtain compact Stirling engines of satisfactory mechanical efficiency. In this paper, analyzes the effect of each link length of the Ross-Yoke mechanism on piston displacement, and in addition, it is studied on the effect of each link length of the Ross-yoke mechanism on piston displacement, and in addition, it is studied on the effect of each factor on the indicated work using the isotherm model. As the result, the piston displacement showed the tendency away from sine wave, and it was proven that the phase angle changed during the cycle.
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Katsunori HANAMURA, Satoshi NISHIO
Article type: Article
Pages
159-160
Published: September 20, 2002
Released on J-STAGE: August 01, 2017
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Operation characteristics of a Sirling engine with combustion in a porous medium (regenerator) were investigated through one-dimensional numerical simulation. The porous medium was assumed to consist of fine spheres with a 0.1mm diameter and have a 98% porosity and a 15mm thickness. The compressed mixture is preheated by the porous medium and is ignited in the vicinity of its power-piston side end. The main reaction occurs in the gas phase, resulting in the increase in the gas temperature. The thermal efficiency becomes higher as the reaction zone is stabilized closer to the porous medium; then, if reaches the maximum, i.e., 57.5%, under the conditions of the revolution speed of 100rpm, the phase relation angle of 55deg., and the concentration of 2vol.% methane in air. With increasing concentration, the revolution speed attaining the maximum thermal efficiency is shifted to the high-speed side. The thermal efficiency higher than 55% was obtained over a range of the revolution speed from 50 to 250rpm.
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Sanyo Takahshi, Nariyoshi Kobayashi, Hirohide Furutani, Norihiko Iki, ...
Article type: Article
Pages
161-162
Published: September 20, 2002
Released on J-STAGE: August 01, 2017
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Cycle simulation was made on a SOFC-Stirling engine combined system in which the SOFC served as a topper and the Stirling engine worked as the bottoming cycle to evaluate partial load characteristics. The calculation showed that the system efficiency under low load is expected to be still on a high level although the heat loss causes a significant decrease in the efficiency. Also, the comparison with SOFC system revealed that the combined system is advantageous in case the operation of SOFC is difficult at high cell temperature and high hydrogen utilization factor.
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Toshio OTAKA, Masahiro OTA
Article type: Article
Pages
163-164
Published: September 20, 2002
Released on J-STAGE: August 01, 2017
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A prototype Stirling refrigerator employing helium as a working fluid has been investigated to determine whether a freon-free machine is a viable alternative for the current household refrigerator. A displacer-type Stirling cycle machine of 100 W capacity was designed and tested by varying the frequency. COP was, however, below the designed COP, primarily because a significant amount of work was lost in the power transmission mechanism between the motor and the piston. The operational characteristics of the Stirling refrigerator have been clarified. These results demonstrate that the Stirling refregerater is one of the promising candiate as a new refrigerationsystems.
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Hiroshi SEKIYA, Takahiro NAKAMURA, Itsuo NAKAZAKI
Article type: Article
Pages
165-166
Published: September 20, 2002
Released on J-STAGE: August 01, 2017
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The authors had developed a Stirling/cooler and cooling unit (single Stirling cooling unit). In addtion, a double Stirling cooling unit installing two Stirling coolers has been developed to aim at increasing in the cooling capacity of unit. This paper presents a tandem type Stirling cooler which is built up by connecting two Stirling coolers with coupling the crank shafts directly. The cooling unit with the trandem type Stirling cooler is superior to the double Stirling cooling unit, because motor input decreases and buffer tank is not necessary. So the tandem Stirling cooler could be very useful to make refrigeration systems higher efficiency, more compact and cost down.
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Masafumi NOGAWA, Shaowei ZHU, Tatsuo INOUE
Article type: Article
Pages
167-168
Published: September 20, 2002
Released on J-STAGE: August 01, 2017
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We have studied a new conceptive Stirling refrigerator. It is a culse tube type Stirling refrigerator that has a bigger extra space, called 'pulse tube', between the low temperature heat exchanger and the expansion space. The advantage of the pulse tube type Stirling refrigerator is that the mean gas temperature in the expansion space can be kept around the room temperature by the function of pulse tube. We attempt to make sure gas temperature increasing in the expansion space of the pulse tube type Stirling refrigerator by employing the numerical cycle simulation based on a nodal analysis.
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Takeshi HOSHINO, Masato SAKURAI, Shoichi YOSHIHARA, Mitsuru OHNISHI
Article type: Article
Pages
169-170
Published: September 20, 2002
Released on J-STAGE: August 01, 2017
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For Japanese space developments, the only available energy source for long-term space activity is solar energy. On the other hand, a life support system for manned space activity contains physical or/and chemical reactors, and consumes immense quantities of energy. The most of required energy for a life support system is thermal energy to heat reactors. Therefore, it is necessary to utilize solar energy as thermal energy. A conceptual model of a life support system was designed. This is a self-contained partially circulated life support system, called the SEPAL. The most significant feature of the SEPAL is that the system includes an energy supply subsystem. Based on this concept, an oxygen and hydrogen production subsystem using solar thermal energy as an energy source has been developed in order to demonstrate the advantages of solar thermal energy utilization. This system composed of a Stirling engine generator and a water electrolysis system using PEM. This paper describes test results of the Stirling engine generators. In addition, the significant design features and preliminary test results of the oxygen and hydrogen production system.
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Norio OBATA, Sumio YAGYU, Naotsugu ISSHIKI
Article type: Article
Pages
171-172
Published: September 20, 2002
Released on J-STAGE: August 01, 2017
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KUBOTA has been developing a gas engine-driven Stirling heat pump (STHP) system using both engine shaft power and engine exhaust heat. This STHP is a heat-assisted Stirling heat pump and is constructed as two sets of three-cylinder machines, each a combination of two Stirling sub-systems; one a power producer and one a heat pump. This paper describes the system schematics and the system performances. The tests were performed at concurrent cooling and heating operations, fueling methanol reformed gas (CO+2H_2). A cooling capacity of 4.8kW at 280K and a heating capacity of 9.1kW at 318K were attained, and the total COP was reached to 2.1 at the input fuel basis. It was shown by the performance tests that the STHP had high COP and could construct a high performance CFC-free heat pump system.
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Kazuhiro HAMAGUCHI, Hiroshi SEKIYA, Masahisa OOTAKE
Article type: Article
Pages
173-174
Published: September 20, 2002
Released on J-STAGE: August 01, 2017
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Concerns with global warming and the need to reduce CO_2 emissions are glowing internationally. As one of the solutions, the introduction of co-generation system to ordinary homes is being attempted. The examination of the residential co-generation system is carried out in search of electric power decentralization, energy saving, environment and economical efficiency. It views fuel cell and small gas engine as thermoelectric conversion equipment of this system with hope, and the examination of the small Stirling engine has just begun. The merit of the Stirling engine introduction is big, when cold region with much heat demand, diversity of the fuel, operating cost, and the vibration and noise reduction are taken into consideration. This paper describes energy user study results of ordinary homes around Sapporo City. The possibility of the introduction of the residential co-generation system using Stirling engine is examined. Based on the survey, the residential co-generation system using Stirling engine for cold region is proposed.
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Masashi Noguchi, Shizuo Yasuda, Hirotoshi Horizoe, Jun Sato, Yoshinori ...
Article type: Article
Pages
175-176
Published: September 20, 2002
Released on J-STAGE: August 01, 2017
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The char which removed 70%∿95% of the chlorine by the thermal cracking of municipal waste at 400∿450℃is burned in a fluidized bed having a superheater made from ordinary low cost tubing and electrical power can be generated with a 30% efficiency by recovering superheated steam (7.85∿9.81MPa, 500℃). At the same time, the pyrolysis gas is burned with air in ash melting furnace of the vertical swirling type, in which ash can be melted continuously at 1300∿1500℃. The slag from the melted ash is reusable in a number of ways. These processes occur when there is more than 1500kcal/kg of LHV of waste. This system is compacted with a low excess air ratio (1.2∿1.3), and pollutant emissions at the outlet of the furnace are reduced.
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Yasushi ISSHIKI, Keisuke NAKAGAWA
Article type: Article
Pages
177-178
Published: September 20, 2002
Released on J-STAGE: August 01, 2017
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Recycling of Municipal Solid Waste (MSW) is vigorously promoted in Japan and the necessity of energy recovery from organic waste is increasing. A methane fermentation demonstration plant for organic waste in Kyoto City is operated of about three years. Three kinds of wastes (commercial waste from hotels, yard waste and used newspaper) mixed at various ratios are used. The plant has maintained stable operations with each mixture, generating biogas by the decomposition of VS at the rate of about 820m^3_N-dry/ton-VS. Methane average content is 57.4%-dry in biogas. We obtained the technical evaluation from the Japan Waste Management Association in Sep. 2001 in terms of methane gas recovery and composting as Kompogas methane fermentation System.
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Tomonori YAMAJO, Shinji ASAKURA
Article type: Article
Pages
179-180
Published: September 20, 2002
Released on J-STAGE: August 01, 2017
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The discharge of waste plastics reached to 9,760,000 tons in 1999. Among these, the ratio of 46% was used effectively, and 54% was simple incineration and reclamation disposal. A large amount of simple incineration and reclamation disposal is not only the problem from a viewpoint of environmental preservation that, but the effective use is called for construction of recycle system society. In this study, useful synthetic gas is manufactured by the Pressurized Two-Stage Gasification technology using waste plastics, which is developed and the commercialized in recent years, and is utilized as a fuel of gas turbine for the efficient combined cycle power generation system.
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Emi YOSHITAKA, Takashi KIGA
Article type: Article
Pages
181-182
Published: September 20, 2002
Released on J-STAGE: August 01, 2017
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Coal is important fuel for electric power generating plants, because coal can be supplied from a lot of countries inexpensively and stability. On the other hand, CO_2 release from coal is more than those from natural gas and oil. It is effective for the decrease of CO_2 release from coal fired electric power generating plants that the fuel such as waste and biomass is co-fired as substitute for a part of coal. It is possible to generate electricity from waste and biomass in efficiency as high as 40%. We conducted tests of both co-pulverizing and co-firing with a blend of wood and coal at the combustion test facility. Co-firing a few percents of wood with coal in pulverized coal fired power generating plant is possible with minimum installation of additional equipment.
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Satoru GOTO, Sumio KURODA, Yoshifumi NISHI
Article type: Article
Pages
183-184
Published: September 20, 2002
Released on J-STAGE: August 01, 2017
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It is necessary to develop the high efficiency gas engine which uses waste origin low calorie gas for effective use of energy resources. For example, the composition of the waste origin low calorie gas is composed of H_2CO.CO_2 of 30∿35vol% each other. The low calorific value is about 7.5MJ/m^3_N which is equivalent to 1/5 of city gas. Authors have studied the combustion characteristics and practical tuning method of the pilot ignition gas engine.
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Kimihito NARUKAWA, Etsuo SATOU, Tadashi TANAKA, Hiromi KOIZUMI
Article type: Article
Pages
185-186
Published: September 20, 2002
Released on J-STAGE: August 01, 2017
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The laminar burning velocity test and diffusion flame combustor test were carried out for surveying the combustion characteristics of dimethyl-ether (DME), comparing with methane and propane. Results from the present work are as follows : (1) Burning velocity of DME is 110cm/s, and burning velocity of DME is faster than methane and propane. (2) NOx emission of DME diffusion flame combustion is equal with propane and higher than methane. (3) CO emission of DME diffusion flame combustion is equal with methane and propane.
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Tomomi KOGANEZAWA, Hiroshi INOUE, Nariyoshi KOBAYASHI
Article type: Article
Pages
187-188
Published: September 20, 2002
Released on J-STAGE: August 01, 2017
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In this work, an experimental study is carried out to obtain the combustion characteristics of a diffusion flame combustor used under high humidity condition of the advanced humid air turbine (AHAT) system. Low flame temperature caused by high humidity condition is expected to decrease NOx emission, but it may weaken flame stability. The influence of humidity on NOx emission and flame stability is studied with combustion test using three types of combustor with different axial distribution of combustion air. The flame stability of diffusion flame combustor is enough for AHAT operation. NOx emission of the combustor with local humidification is 10ppm at 16.8wt% of humidity. The result shows that it is possible to cope with both flame stability and NOx reduction in AHAT system.
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Yasutomo KANEKO, Kazushi MORI, Masayuki TOMII, Toshio NAGASHIMA
Article type: Article
Pages
189-190
Published: September 20, 2002
Released on J-STAGE: August 01, 2017
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For the purpose of the reliability improvement, a friction damper is sometimes adopted in the vane of the gas turbine compressor. In order to verify the damping characteristic of the damper vane, the non-contact magnetic exciter was made and the excitation test of the damper vane was carried out. On the other hand, the analysis code was developed for predicting the damping characteristic of the damper vane. The frequency and damping of the damper vane measured by the excitation test was compared with the calculated results. The results of the test and the analysis showed that the damper vane has a excellent damping characteristic.
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Masahiro OSAKABE, Sachiyo HORIKI, Kunihiko MOURI
Article type: Article
Pages
191-192
Published: September 20, 2002
Released on J-STAGE: August 01, 2017
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The world's first cruise ship powered by the combined cycle of gas and steam turbines entered service in June 2000. The environmentally friendly gas turbine was chosen instead of the diesel engine. Though the use of distillate marine gas oil for the gas turbine will produce a higher operating cost, it is believed that the higher cost is offset by the significant advantages and merits of the combined cycle. The output electric power could be controlled without the degradation of the total efficiency by adapting two small gas turbines instead of a large one. The system could be preferable also in the distributed power generation systems in lands.
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Takanari OKAMURA, Kunihiko MOURI
Article type: Article
Pages
193-194
Published: September 20, 2002
Released on J-STAGE: August 01, 2017
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This paper presents the recent trend of the distributed power in Hachinohe districts and a proposal of future electric power network. Real time control by IT of various distributed powers and utilization of biomass fules are characteristic of this network that optimizes the power supply and decreases environmental pollution. Simultaneously, procedure to realize this proposal is shown.
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