-
Takaaki Morimune, Nobuhiro Furusho
Article type: Article
Pages
95-96
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
CONFERENCE PROCEEDINGS
RESTRICTED ACCESS
Electrical discharge process using corona is effective in reducing particulate matter (PM) and nitrogen oxides (NOx) of diesel engine exhaust. We experimentally evaluate the application of DC corona discharge reactor to reduce the PM and NOx from diesel exhaust. Particulate trapping in a corona reactor can be accomplished by electrostatic precipitation. The accumulated PM on a nichrome electrode of reactor can be regenerated by the controlled burning process. In a corona reactor, NO is oxidized to NO_2 and NO_2 reacts with H_2O contained in exhaust. NOx decreases as a result of HNO_3 formation in a reactor. HNO_3 is neutralized on the filter paper contained alkali. A corona reactor consists of cylindrically-shaped outer electrode made of stainless steel and central electrode made of rolled nichrome wire. Dimensions of prototype reactors are ID×length=φ54×300,φ28×160,a flow rate of 14l/min, resulted in space velocity of about 9200and 1250/hr. In this study, the effects of corona voltage, current and the space voltage, current and the space velocity of reactor on the soot collection efficiency and the NOx removal efficiency are investigated. Also discussed is the particle size distribution of soot collected by a reactor. Experimental results show that 1) a corona discharge reactor is capable of reducing both diesel particulates and NOx simultaneously, 2) Fine-particles less than φ0.5μm can be removed by a corona process.
View full abstract
-
Takayuki ITO, Masato Ueda, Takaaki KITAMURA, Jiro SENDA, Hajime FUJIMO ...
Article type: Article
Pages
97-98
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
CONFERENCE PROCEEDINGS
RESTRICTED ACCESS
The detailed chemical kinetics was implemented into the KIVA-3V multidimensional CFD code to clarify the soot formation process in diesel jet flame. The detailed soot model is based on a combination of a detailed reaction mechanism and kinetic soot model based on the method of moments, which begins with fuel pyrolysis, followed by the formation of polycyclic aromatic hydrocarbons, their growth and coagulation into spherical particles, and finally, surface growth and oxidation of the particles. The model can describes the spatial and temporal properties of soot formation such as soot precursors distributions, nucleation rate and surface reaction rate.
View full abstract
-
Masato UEDA, Takayuki ITO, Jiro SENDA, Hajime FUJIMOTO
Article type: Article
Pages
99-100
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
CONFERENCE PROCEEDINGS
RESTRICTED ACCESS
To achieve more improvement of diesel combustion and for health issues, it is important to get the information of soot particle characteristics in the diesel jet plume such as the distribution of soot concentration or particle size. In this study, LII (Laser-Induced Incandescence), especially, TIRE-LII (Time-Resolved-LII) was applied to estimate the particle size under unsteady spray combustion, and soot volume fraction was also measured. To apply TIRE-LII to diesel jet, many LII characteristics were tested by using premixed or diffusion flame bumer and numerical simulation. The result sows that, dense regions of soot dominantly localized in the periphery the downstream of the plume. And as fuel injection progresses, the distribution of large soot particle diameter region extends shifting downstream of the plume.
View full abstract
-
Tetsuya AIZAWA, Masayuki HOSAKA, Hidenori KOSAKA, Yukio MATSUI
Article type: Article
Pages
101-102
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
CONFERENCE PROCEEDINGS
RESTRICTED ACCESS
Measurements of Excitation-Emission Matrix (EEM) of polycyclic aromatic hydrocarbons (PAHs) in an atomospheric diffusion burner flame were conducted using a multi-wavelength excitation laser in order to demonstrate the potential of the EEM fluorometry for investigation of soot formation processes in flames. The PAHs in the flame were excited by a coherent multi-wavelength "rainbow" laser light generated by converting the 3rd harmonic (355nm) of a pulsed Nd : YAG laser using a Raman cell frequency converter filled with hydrogen (0.6MPa). The fluorescence from the PAHs excited by different wavelengths in the flame was simultaneously captured using a spectrometer and an ICCD camera as EEM images.
View full abstract
-
Takemi CHIKAHISA, Tomomi KANEKO, Takesi FUJII, Yukio HISHINUMA
Article type: Article
Pages
103-104
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
CONFERENCE PROCEEDINGS
RESTRICTED ACCESS
Similarities in the structure of spray flames suggest that higher fuel injection speeds would reduce NOx emission as the fuel residence time in the reaction zone would shorter. However, in diesel combustion it is commonly known that NOx emissions increase when the fuel injection velocity is increased. The authors have suggested from experimental and numerical analysis that the mixing time scale is significantly large at the spray tip region and existence of this unsteady structure is the major difference of the two flames. The purpose of this paper is to examine the effect of pre-injection of inert gas and air for the reduction of NOx : the aim was to eliminate the weak mixing zone at the tip and to create a fuel flow similar to a well developed jet structure. Experimental results showed NOx emissions decreased with his method, and the results provide clues to ways of reducing NOx in diesel spray flames.
View full abstract
-
Mitsuharu OGUMA, Shinichi GOTO, Hidefumi HATSUZAWA, Mitsuru KONNO
Article type: Article
Pages
105-106
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
CONFERENCE PROCEEDINGS
RESTRICTED ACCESS
For better understanding of in-cylinder combustion characteristics in a direct injection DME engine, radicals were observed using the spectroscopic method. In this experiment, after passing through a spectroscope emission intensity was measured by photomultiplier. Two strong emission intensities were found in 427nm and 431.4nm. Emission intensity of 427nm became strong from the early stage to middle stage of diffusion combustion period. Emission intensity of 431.4nm became strong from the middle stage to second half of diffusion combustion period. The line spectra where strong emission intensities were observed in this DME engine shift from those that are obtained on the burner flame.
View full abstract
-
Kouseki SUGIYAMA, Masataka KAJIWARA, Makihiko MORI, Shinichi GOTO, Tom ...
Article type: Article
Pages
107-108
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
CONFERENCE PROCEEDINGS
RESTRICTED ACCESS
In this research, the examination apparatus in which lubricities evaluation is possible was manufactured by arbitrary pressure according to the lubricities examination method (HFRR) of diesel fuel. The lubricity was examined about the DME (Dimethyl ether) for diesel engines using the examination apparatus. The fixed value was acquired, when an inside was changed into a seal state and the lubricity was measured. Consequently, it became a value about near diesel fuel, and when suitable lubricity was maintained, it has checked.
View full abstract
-
Kazunori YOSHIDA, Hideaki KASHIWAGI, Takahiro KOSEKI, Shinichi TAMURA, ...
Article type: Article
Pages
109-110
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
CONFERENCE PROCEEDINGS
RESTRICTED ACCESS
Preservation of the global environment and diversification of energy sources have become pressing issues in recent years, and there have been demands for the reduction of nitrogen oxides (NOx) and particulate matter (PM) that are the principal causes of air pollution in the exhaust gas of diesel engines. In this research, therefore, DME was supplied to a test diesel engine and the premixed mixture was burned in an HCCI process. The resultant flame light was extracted from the combustion chamber and analyzed to determine the combustion characteristics. Based on the experimental data, this paper discusses the relationship between the equivalence ration and these observed tendencies.
View full abstract
-
Wakako SAHASHI, Chikashi OIKAWA, Akihiko AZETSU
Article type: Article
Pages
111-112
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
CONFERENCE PROCEEDINGS
RESTRICTED ACCESS
The compression ignition of Dimethyl Ether has two stages of combustion, which were known as cool and hot flame respectively. Since the temperature and pressure of mixture was increased by the heat release during cool flame, the amount of heat release during cool flame has strong effects on ignition of hot flame. In this paper, the effects of N_2/CO_2 addition on heat release of cool flame were investigated from experiments and computations. The heat release on cool flame was reduced with N_2 addition, however, it was increased with CO_2 addition. From the systematic experiments and chemical kinetic computations, it was confirmed that the amount of heat release at cool flame depends strongly on the concentration of O_2at cool flame onset.
View full abstract
-
Wakako SAHASHI, Chikashi OIKAWA, Akihiko AZETSU
Article type: Article
Pages
113-114
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
CONFERENCE PROCEEDINGS
RESTRICTED ACCESS
The characteristics of CO emission from HCCI engine operated on Dimethyl Ether have been investigated from experiments and chemical kinetic computations. Normally, the compression ignition of Dimethyl Ether has two stages of combustion, however, in some cases, it has three stages of combustion. The 3rd stage of combustion was mainly composed of CO oxidation reactions and played an important role in CO emission. From the computations, it was confirmed that the dominant path for CO oxidation is the reaction of CO+OH=CO_2+H. The produced H atoms react with O2 molecules and produce OH+O or HO_2 The CO oxidation becomes active as increasing the blanching fraction to OH+O. However, with the addition of CO_2 to the mixture, the branching fraction to HO_2 was increased, resulting in a higher CO emission. Though the addition of CO_2 is effective in suppressing a knocking, it has an inferior effect on CO emission.
View full abstract
-
Hiroshi YAMASAKI, Hajime TANAKA, Daisuke SEGAWA, Toshikazu KADOTA, Mit ...
Article type: Article
Pages
115-116
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
CONFERENCE PROCEEDINGS
RESTRICTED ACCESS
Experimental study has been carried out to reveal the interacting effect of the onset of micro-explosion in the combustion processes of emulsion droplet array. Detail measurements of waiting time for onset of micro-explosion are made for base fuels f n-hexadecane and n-dodecane, and water contents of 0.1 and 0.2. The fuel in water emulsion consisting base fuel and water doped with small amount of surfactant were tested after degasification. The results showed that the waiting time for the onset of micro-explosion in the droplet array were correlated to the Weibull distribution. It is found that the onset of micro-explosion is accelerated by the micro-explosion of an adjacent droplet. This interaction results in shortening the lifetime of the emulsion droplet array.
View full abstract
-
Masaaki Sato, Hiromitsu Umano, Yoshiyuki Kidoguchi, Kei Miwa
Article type: Article
Pages
117-118
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
CONFERENCE PROCEEDINGS
RESTRICTED ACCESS
The purpose of this study is to improve ignitability and combustion stability of CNG intermittent gas jet for gas-fuelled engines. The effect of spark position and H_2 addition on ignition and combustion of CNG was investigated by high-speed schlieren photography with the constant volume combustion chamber, burned gas measurement and analysis of gas flow employing laser sheet technique. It has been shown by the results that ignitability of CNG jet is improved by controlling jet velocity. Ignition near injector and at off-set position of jet axis is effective to reduce jet velocity and improve ignitability. H_2 addition improves stability of combustion.
View full abstract
-
Mitsuru KONNO, Zhili CHEN, Daikuke KASHIWAGI
Article type: Article
Pages
119-120
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
CONFERENCE PROCEEDINGS
RESTRICTED ACCESS
Combustion mechanism of the methane/dimethyl ether (DME)/air homogeneous charge compression ignition (HCCI) combustion was investigated by in-cylinder gas sampling tests and numerical kinetics calculations. The results showed that the main functions of DME for methane ignition were the temperature rising effect by low temperature reactions of DME and the supply of OH radicals. It was possible to extend the operation range to an overall equivalence ration of 0.54 without knocking, when ignition was retard after the top dead center, by controlling the DME quantity.
View full abstract
-
Masahiro ISHIDA, Tetsuya TAGAI, Tomofumi NAKASHIMA, Hironobu UEKI
Article type: Article
Pages
121-122
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
CONFERENCE PROCEEDINGS
RESTRICTED ACCESS
Homogeneously charged natural gas was burned in diesel engine by injecting a small amount of gas oil as an ignition source. The effects of the equivalence ration of natural gas, the injection amount and injection timing of gas oil, the intake temperature and the EGR rate, on ignition, the burninig rate of natural gas and the knock limit were investigated experimentally. The results show that natural gas starts to burn after ignition of gas oil, and the ignition delay is determined by the in-cylinder mean gas temperature at ignition timing, and the onset of knocking was almost dominated by the in-cylinder mean gas temperature which is around 1600K.
View full abstract
-
Masahiro ISHIDA, Tetsuya TAGAI, Issei OISO, Hironobu UEKI
Article type: Article
Pages
123-124
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
CONFERENCE PROCEEDINGS
RESTRICTED ACCESS
Methanol was injected into each intake port of a 4 cylindered diesel engine and it was ignited by injecting a small amount of gas oil. The effects of the equivalence ration of methanol, the injection amount and the injection timing of gas oil, the intake temperature and the EGR rate on igtnition, the burninig rate of methanol and the knock limit were investigated experimentally. Ignition delay and the burning rate of methanol was compared with those of natural gas. It is found that the ignition delay of methanol is determined by the mean gas temperature at the ignition timing as is the same in the case of natural gas, and the onset of knocking is dominated by the mean gas temperature which is lower than the case of natural gas.
View full abstract
-
Yasuo MORIYOSHI, Seok woo Kim
Article type: Article
Pages
125-126
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
CONFERENCE PROCEEDINGS
RESTRICTED ACCESS
A production two-stroke Schnurle-type gasoline engine was modified to enable compression ignition in both port fuel injection and in-cylinder direct injection. Using this engine, examination of compression ignition operation conditions and engine performance tests were carried out. As a result, direct injection was found superior to port injection in exhaust gas emissions and fuel efficiency, and some interesting combustion characteristics, such as shorter combustion period in higher engine speed were also found.
View full abstract
-
Yuichiro KOJIMA, Takuya TAKEI, Norimasa IIDA
Article type: Article
Pages
127-128
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
CONFERENCE PROCEEDINGS
RESTRICTED ACCESS
In this study, the exhaust gas composition was clarified by using a gas chromatography, and combustion completion was considered in 2-stroke HCCI engine. In Exhaust gas composition, n-Butane was high concentration as opposed to calculation results and intermediate products (CO, C_2H_4,C_3H_6,CH_4,C_2H_6) also exhausted. In actual engine, it was considered that mixture near cylinder wall couldn't be ignited because of heat loss to wall. This region was almost 0.75-1.56mm from wall by calculated from exhaust gas composition and concentration by 3 models. Increasing maximum in-cylinder gas temperature until 1600K, combustion efficiency became higher and HC emissions became lower, but over 1600K, combustion efficiency kept constant 82±3% and HC emissions became higher again.
View full abstract
-
Ock Taeck LIM, Naofumi SENDOH, Norimasa IIDA
Article type: Article
Pages
129-130
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
CONFERENCE PROCEEDINGS
RESTRICTED ACCESS
The effect of Research Octane Number (RON) on the ignition delay from Homogeneous Charge Compression Ignition (HCCI) has been experimentally investigated By varying the RON, it was possible to ascertain whether or not RON is the main resource of Ignition delay. Additionally, the information on Equivalence ratio for varying RON was obtained. The tests were performed on a RCM (Rapid Compression Machine) fueled with n-Heptane and iso-Octane. The result showed that increasing RON (0,70,80,90,100), the ignition delay of low temperature reaction (tL) and high temperature reaction (tH) is longer. And the temperature of reaction increases by about 30K. A similar comparison of the effect of Equivalence ration on ignition delay at RON(70,80,90), tL and tH is longer.
View full abstract
-
Kengo KUMANO, Yudai YAMASAKI, Norimasa IIDA
Article type: Article
Pages
131-132
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
CONFERENCE PROCEEDINGS
RESTRICTED ACCESS
In this study, the effect of pre-mixture homogeneity on the combustion process in HCCI engine was investigated. Spontaneous luminescence from DME/Air mixture combustion was captured by using a framing streak camera with a 4-stroke optical access engine. In order to change spatial distribution of fuel in combustion chamber, the engine has two different fuel injection port and fuel injection timing was controlled by a gas injector. The result showed a heterogeneous combustion with a special variation in case of heterogeneously premixed charge. As combustion duration in heterogeneous condition is longer than homogeneous condition and combustion efficiency was almost constant in both conditions, it was clarified that heterogeneously premixed charge attracted slow combustion.
View full abstract
-
Katsuya SAIJYO, Takafumi KOJIMA, Kazuie NISHIWAKI, Yoshinobu YOSHIHARA
Article type: Article
Pages
133-134
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
CONFERENCE PROCEEDINGS
RESTRICTED ACCESS
A combustion process in an HCCI engine has been simulated using CFD code in conjunction with 5-step global reaction model for hydrocarbon fuels. The Large Eddy Simulation (LES) was employed to describe turbulent transport. Two different initial conditions were prepared. One is the homogeneous fuel distribution and the other is the heterogeneous fuel distribution. From the calculation results of combustion process, it is found that the heat release rate for the heterogeneous case shows more moderate than that of the homogeneous case.
View full abstract
-
Tatsumi KITAHARA, Masaru OTSUBO, Kotaro FUJISAKI, Atsushi OKADO
Article type: Article
Pages
135-136
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
CONFERENCE PROCEEDINGS
RESTRICTED ACCESS
Calculations and experiments were carried out to clarify the load carrying capacity of the crosshead-pin bearing with wedge geometry incorporated oil-grooves for large size two-stroke diesel engines. Reducing the clearance ratio is advantageous for enhancing squeeze action on the entirety of the bearing pads, thereby decreasing the maximum oil film pressure. However, this also has a negative aspect of reducing the oil film thickness, thereby causing the load carrying capacity to decrease. Even when the clearance ratio becomes very low, incorporating a proper wedge geometry on both sides of the oil-grooves is an effective means to increase the oil film thickness, and thereby to raise the load carrying capacity.
View full abstract
-
Hidetsugu YAMAMOTO, Syuji YAMAKAWA, Takanori KATO
Article type: Article
Pages
137-138
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
CONFERENCE PROCEEDINGS
RESTRICTED ACCESS
Increase of soot contaminated in engine oil caused by EGR system accelerates diesel engine wear, especially valve train wear. The wear is mainly caused by soot abrasively. It is important to evaluate the hardness of soot to wear protection. In this study, a rig test (Block on ring tester) has been conducted by used oil that contained soot. The test pieces that have different hardness were used to determine hardness of soot. The wear scar caused by soot was observed on the test piece surfaces that were softer than HV1500,but was not observed on the hard surface (HV1930). The hardness of soot was estimated harder than HV15 , softer than HV1930.
View full abstract
-
Yoshinari SATO, Masato MIKAMI, Naoya KOJIMA
Article type: Article
Pages
139-140
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
CONFERENCE PROCEEDINGS
RESTRICTED ACCESS
The clearance between a piston skirt and a cylinder liner in an engine is filled with an oil-film. The pressure in the oil-film affects the movement of the piston. The pressure distribution in the oil-films is numerically simulated in the several former studies. However, it has not been experimentally measured yet. In this study, the pressure in the oil-film in a running engine is measured through a pressure transducer fixed in cylinder block. The pressure distribution is compared between the measurements and the numerical simulations
View full abstract
-
Souichi SAEKI, Douglas Hart, Carlos Hidrovo
Article type: Article
Pages
141-142
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
CONFERENCE PROCEEDINGS
RESTRICTED ACCESS
This paper presents much information about YAG(532) laser dyes dissolved into oil which can be utilized to measure oil film thickness and temperature. A spectroscopy analysis was conducted to obtain fluorescence and absorptivity spectra using spectrofluorometer and spectrophotometer, respectively. Spectroscopic dependency of each single-dye on temperature was evaluated to discover the best indicator of temperature. Some promising combinations of two dyes were selected to be applied to Dual Emission LIF (DELIF) temperature measurement on the basis of this information. The possibility of DELIF were examined using a spectrofluorometer. Consequently, some of the best dye-combinations was recommended, which could make the most of DELIF and Emission Reabsorption LIF (ERLIF) film thickness measurement. The ratio-metric LIF technique was found to be very helpful for minimizing of photo-degradation errors originating from the dye-bleaching and oil-oxidation caused by high temperature.
View full abstract
-
Akihiko AZETSU, Yusuke UEGAKI, Santi SRIVICHARNKUL
Article type: Article
Pages
143-144
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
CONFERENCE PROCEEDINGS
RESTRICTED ACCESS
A new measurement technique of liquid film thickness, such as oil film thickness, was proposed in this study. In this technique, a fluorescent dye was dissolved in the liquid film and excited by a laser light. With appropriate concentration of fluorescent dye, reflectivity of both boundary surfaces of liquid film and intensity of incident Laser light, a beam of light with wavelengths corresponding to a liquid film thickness was emitted perpendicular to the liquid film by stimulated emission of radiation. To evaluate the possibility of proposed technique, the trial experiments were performed using water as a liquid, Rhodamine B as a fluorescent dye and the 2nd harmonic of Nd : YAG Laser light, 532nm, as incident light source. In this paper, the effects of the intensity of laser light, the concentration of fluorescent dye were examined experimentally.
View full abstract
-
Takashi SUZUKI, Keisuke UCHIDA, Yasufumi OGURI, Masatake YOSHIDA
Article type: Article
Pages
145-146
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
CONFERENCE PROCEEDINGS
RESTRICTED ACCESS
Temperature distribution as the flame propagated and approached the wall of the combustion chamber was measured by real-time holographic interferometry, which mainly consisted of an argon-ion laser and a high-speed video camera. The experiment was done with a constant volume chamber and propane-air mixture with several kinds of equivalence ratios. From the experimental results, it can be found that the temperature distribution outside the zone from the surface of the combustion chamber to 0.5mm distance could be measured by counting the number of the interference fringes, but couldn't within this zone because of lacking in the resolution of the used optical system. As a result of analysis, it was found that the minimum distance from the preheating place at 1200-1400K-temperature to the wall changed as the equivalence.
View full abstract
-
Toshihiro NAKASATO, Kenichi TANIOKA, Mitsuru KONNO, Zhili CHEN, Shinic ...
Article type: Article
Pages
147-148
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
CONFERENCE PROCEEDINGS
RESTRICTED ACCESS
Viscosity of dimethyl. Ether (DME), bio-diesel fuel (BDF) and BDF/DME composite fuels were measured by capillary tube viscometer for the temperature range of 20-80℃. As the results, kinematic viscosity of DME was 0.197cSt ad 30℃, which is about 4% of the diesel fuel viscosity. Kinematic viscosity of BDF was 30% higher than that of the diesel fuel. If 10wt% of DME was added to BDF, the viscosity decreased to much
View full abstract
-
Soichi ISHIHARA, Yoshio MURAKAMI, Kohei NAKASHIMA, Shinji FURUICHI
Article type: Article
Pages
149-150
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
CONFERENCE PROCEEDINGS
RESTRICTED ACCESS
We reported in the previous paper that the fresh air short-circuits not only from the scavenge port or the crankcase through the piston clearance to the exhaust port (leakage flow) but also from the exhaust port through the piston clearance to the scavenge port or the crankcase (leakage reverse flow) for the two-stroke engine. In this paper the pressure of the scavenge port, the crankcase and the exhaust port was measured. Using the pressure and the amount of the air delivered to the cylinder, the leakage flow rate and the leakage reverse flow rate were calculated. We clarified that the leakage flow rate is almost the same and the leakage reverse flow rate is reduced when the delivery ratio is increased.
View full abstract
-
Masao YOSHIDA, Soichi ISHIHARA, Yoshio MURAKAMI, Masago YAMAMOTO
Article type: Article
Pages
151-152
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
CONFERENCE PROCEEDINGS
RESTRICTED ACCESS
This is a study of the effect of residual heat between fins of air-cooled cylinders. The object of the study is to find out what portion of cylinders should be cooled in order to achieve the optimum air-cooling effect and uniform cooling of fins. Aluminum-alloy cylinders with trapezoidal fins were made and used as experimental cylinders. Five cylinders were made with different pitches of fins and the maximum number of fins was installed. A dedicated testing system, mainly composed of a blower, a differential pressure gauge, a data logger and a test section, was also made. The ventilation speeds were 0,20,40and 60km/h. Thin thermocouples were installed between the fins of sample cylinders and local temperatures were measured at 30 points.
View full abstract
-
Yingjun JIN, Yutaka TAKADA, Norimasa IIDA
Article type: Article
Pages
153-154
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
CONFERENCE PROCEEDINGS
RESTRICTED ACCESS
The actual NOx emission at roadside in a narrow street was clarified by no-board measurement system. The factors that caused an intensive NOx pollution were analyzed, considering road infrastructures, traffic conditions, driver's operations and NOx emission pr running distance. As the results, it was found that obstacles such as utility poles, parking cars, poor visibility for driver, stops in an intersection, which lead to deceleration and acceleration of a vehicle caused intensive NOx pollution in a narrow street.
View full abstract
-
Shuichi OHMORI, Tadashi NARABAYASHI, Michitsugu MORI
Article type: Article
Pages
155-156
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
CONFERENCE PROCEEDINGS
RESTRICTED ACCESS
Using high-performance steam injector (SI) system technology, which outperforms conventional SIs in application of a wider operating range and enables multistage parallel operation, we have carried out a study on a simplified nuclear power plant design to apply high-performance SIs in core coolant injection systems and feedwater heating systems. The most use of substantially simplified SIs and application of this technology for nuclear power plants could incorporate innovative ideas to make plants free from severe accidents, and reduce material, and develop a severe-accident-free design to enhance the reliability and international cose competitiveness of Japanese nuclear power plants. The present research project has been carried out by Tokyo Electric Power Company, Toshiba Corporation, and six Universities in Japan, funded from the Institute of Applied Energy (IAE) of Japan as the national public research-funded program.
View full abstract
-
Tadashi NARABAYASHI, Michitsugu MORI, Takayuki TERAI, Haruki MADARAME, ...
Article type: Article
Pages
157-158
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
CONFERENCE PROCEEDINGS
RESTRICTED ACCESS
In order to develop a competitive and high performance Next Generation BWR with fossil power plant, an internal CRD using a heatproof ceramics insulated coil is under development. In case of a 1700MWe next generation BWR, the internal CRDs are installed in a RPV whose size is equivalent to the 1356 MWe ABWR, and there will be no space required for CRDs and CRD exchange under RPV. These advantages realize a compact PCV and reduced volume of a reactor building. Moreover, the internal CRDs eliminate penetration via a bottom flange of RPV, and lower installation level of RPV in a drywell. This brings further advantages of elimination of RIA (Reactivity Induced Accidents) caused by CR withdrawing under pressure boundary broken, and easy IVR (In Vessel Retention) by vessel bottom cooling in case of a severe accidents.
View full abstract
-
Kenichi Tezuka, Michitsugu Mori, Yasushi Takeda, Masanori Aritomi, Hir ...
Article type: Article
Pages
159-160
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
CONFERENCE PROCEEDINGS
RESTRICTED ACCESS
As nuclear power plants are highly aging, readings of flowmeters for reactor feedwater systems drift due to the changes of flow profiles. The causes of those deviations are affected by the change of wall roughness of inner surface of pipings. To cope with those concems, time-of-flight ultrasonic flowmeters are being introduced to nuclear power plants in the United States. However, flow profile factors (PFs), which adjust measurand to real flow rates, also strongly depend on flow profiles. To determine profile factors for actual power plants, manufactures of flowmeters usually conduct factory calibration tests under ambient flow conditions. Indeed, flow measurements with high accuracy for reactor feedwater require them to conduct calibration tests under real conditions, such as liquid conditions and piping layouts. These make it inevitable in quite a few measuring errors for large pipings in power plants. Therefore, the measurement accuracy of flow rate by conventional time-of-flight ultrasonic flowmeters is questionable. This paper discussed sophisticated high-accuracy feedwater flowmeter which directly measures the flow profile of reactor feedwater.
View full abstract
-
Hiroshi IKEDA, Takeshi SHIMIZU, Tadashi NARABAYASHI, Koji NISHIDA, Tos ...
Article type: Article
Pages
161-162
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
CONFERENCE PROCEEDINGS
RESTRICTED ACCESS
Reduction of the pressure drag losses of steam separator systems for BWR (Boiling Water Reactor) plants is advantageous in that it makes the required pump head lower and enhances core stability. And lower pump power contributes directly to cost reduction. In this paper we describe a design procedure for developing steam separators for BWR plants with lower pressure drag losses by means of the combination of a simulation method and a scale-model experiment. It is found from three-dimensional two-phase simulation that the inlet pressure loss and outlet pressure loss in the swirler are dominant and the turning angle of vane and twisting angle of vane are important for separating steam-water mixture in the swirler. We designed the swirler with lower pressure losses using the swirler geometry parameter selected by two-phase simulation method. It is shown that the separator with the improved swirler can decrease pressure losses more than 30 percent compared to the conventional separator.
View full abstract
-
Yukitaka YAMAZAKI, Takahisa KONDO, Tadashi NARABAYASHI, Shinichi MOROO ...
Article type: Article
Pages
163-164
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
CONFERENCE PROCEEDINGS
RESTRICTED ACCESS
In order to verify the two-phase flow simulation method, 1/2.22 scale test section was used for high-pressure two-phase flow test. The pressure characteristics and the separating performance of the improved swirler designed by two-phase simulation method are also verified by 1/2.22 scale model experiment. It is found that the improved swirler can decrease pressure losses by about 59 percent compared to the conventional swirler and it can almost keep the same discharged water rate as the conventional swirler. We confirmed that the separator system with the selected swirler can decrease pressure losses more than 20 percent compared to the total pressure losses of the conventional separator without decreasing the discharged water rate by 1/2.22 scale-model experiment.
View full abstract
-
Kenji NISHIDA, Toshiyuki MIZUTANI, Tadahiko SUZUTA, Yoshiyuki Kondoh, ...
Article type: Article
Pages
165-166
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
CONFERENCE PROCEEDINGS
RESTRICTED ACCESS
A steam generator of PWR plant has moisture separators which have the function to separate water from two-phase flow of water and steam. Recently, corresponding to the request for power uprating of operating plants and /or construction of future plants with large thermal capacity, a development of moisture separator with high performance which can correspond to an increase of steam flow rate has been required. Therefore, we have developed the moisture separator with high performance (J model) by performing the verification test under actual plant operating conditions (high pressure and high temperature). The developed separator features are the followings, (1) to have small diameter of swirl vane hub, (2) to have horizontal slits at riser barrel, (3) to have slots with lips at the top of downcomer barrel. Based on the combination of the high pressure test results and thermal hydraulic analyses results, value of SG moisture carry over (MCO) is evaluated. As a result, evaluated MCO value is less than 0.01%, which is less than our target value of 0.1%.
View full abstract
-
Shoichi MORIYA
Article type: Article
Pages
167-168
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
CONFERENCE PROCEEDINGS
RESTRICTED ACCESS
This paper describes the proposal of "Frequency Range Method" by which metal surface temperature fluctuation can be evaluated using the effective heat transfer coefficient predictid by "the power spectrum method" and fluid temperature fluctuation data. The validity of the Frequency Range Method was examined using parallel impinging jet test data on the basis of comparison of "the Improved Time Range Method" developed by the author. It was found that the metal temperature fluctuations predicted by the two methods agreeded with the corresponding experimental data and the validity of the methods were demonstrated. Metal surface temperature fluctuation was predicted by the two methods. The predicted results appeared to be in good agreement each other and no marked difference in prediction accuracy were found between the Improved Time Range Method and the Frequency Range Method.
View full abstract
-
Kouji SHIINA, Tsutomu KAWAMURA, Kenji OGURA, Kouichi TANIMOTO, Toshihi ...
Article type: Article
Pages
169-170
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
CONFERENCE PROCEEDINGS
RESTRICTED ACCESS
In a branch pipe with closed end, the cavity flow penetrates into the branch pipe from the main loop and the thermal boundary layer occurs because the cavity flow is a hot fluid, but the heat removal causes the colder fluid in the branch pipe. It is possible for the thermal stratification to affect the structural integrity. Therefore, it is necessary to establish the pipe design standard to suppress thermal fatigue. The pipe design standard consists of the maximum penetration depth L_<sv> and the minimum penetration depth L_<sh>. First of all, in order to establish the evaluation method for L_<sh>, the visualization test and the temperature fluctuation test were carried out. Theoretical formula of thermal stratification was introduced from the heat balance model. Using this model, the empirical equation was obtained from the map of fluid temperature fluctuation. The method can predict the vortex penetration depth by cavity flow in the horizontal branch pipe.
View full abstract
-
Nobuyuki TAKENAKA, Masatsugu HASE, Akira NAKAMURA
Article type: Article
Pages
171-172
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
CONFERENCE PROCEEDINGS
RESTRICTED ACCESS
Many pipes branch off from the main pipe in nuclear power plants. When the main flow in the main pipe is hotter than the fluid in a branch pipe that branches off downward, the hot water penetrates into the branch pipe with the cavity flow induced by the main flow and causes thermal stratification. Some experiments were conducted to elucidate the mechanism of this fluctuating thermal stratification. When the main flow was heated and the thermal stratification interface was at the elbow, "burst" phenomena occurred in the interface in connection with great heat fluctuation. Visualization of the temperature fluctuation phenomena caused by the "burst" phenomena was conducted by using thermo chronic liquid crystal.
View full abstract
-
Naoki OGAWA, Youichi IWAMOTO, Itaru MUROYA, Kiminobu HOJO
Article type: Article
Pages
173-174
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
CONFERENCE PROCEEDINGS
RESTRICTED ACCESS
A method for simulating crack growth that takes into consideration the release of residual stress has been developed using an automatic element re-division function. The release of residual stress was estimated using this newly developed method after the initial residual stress distribution was calculated using three-dimensional FE analysis. In order to verify the validity of the method, the release of residual stress was measured at the weld joint of a plate and then compared with estimated values. The results of this comparison confirmed that the simulation method does estimate the residual stress after crack extension to a high degree of accuracy.
View full abstract
-
Masahiro OOKAWA, Akio SHIOIRI, Kumiaki MORIYA, Yoshiaki OKA, Hideo MOR ...
Article type: Article
Pages
175-176
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
CONFERENCE PROCEEDINGS
RESTRICTED ACCESS
This paper describes outline of development porject of Supercritical-water Cooled Power Reactor (SCPR), which has innovative and economical potentials. This project was launched to realize the potential with a national fund. The project is focusing on plant conveptual design, thermal hydraulics and material screening. We have progressed in the core & fuel design, RPV design and BOP design. To minimize the uncertainty brought from the differences between supercritical puressure fossil boilers and the SCPR core conditions, we are carrying out experimental study as well as analytical study. To principally find Zircaloy alternatives, a material screening is performed through simulated irradiation tests, corrosion tests and mechanical tests, at high-temperatures.
View full abstract
-
Hideo Komita, Shinichi Morooka, Hideo Mori
Article type: Article
Pages
177-178
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
CONFERENCE PROCEEDINGS
RESTRICTED ACCESS
Although thermohydraulics of supercritical pressure (SCP) water has been extensively studied for fossil boilers, the core conditions of Supercritical Water Cooled Power Reactor (SCPR) are different from fossil boilers. The purpose of this study is to get better understanding of thermohydraulics performance of SCPR. The small hydraulic tube tests were carried out with SCP HCFC22. The test results were compared with some heat transfer correlations. For normal heat transfer, Watts' correlation shows the best predictability among them. On the other hand, for the deteriorated heat transfer, modified heat transfer correlation was proposed.
View full abstract
-
Kazuaki KITOU, Yoshihiko Ishii, Kouji Fujimura, Masayoshi Matsuura
Article type: Article
Pages
179-180
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
CONFERENCE PROCEEDINGS
RESTRICTED ACCESS
The applicability of three-dimensional heat transmission simulation using a high Re number k-ε model for supercritical pressure R-22 was evaluated. The calculated heat transfer coefficient using the standard k-ε model was good in agreement with the experiment results of Kyushu University researchers below 90℃. On the other hand, the calculated heat transfer coefficient became smaller than experimental results by 20% or more in temperature range above 90℃, which temperature was near the pseudo-critical temperature where coolant properties changed rapidly. C/E using the standard k-ε model and MARS scheme was 0.99 below 90℃, 0.79 above 90℃ and 0.94 of all temperature range. It is expected that standard k-ε model can be applied in where coolant temperature was enough lower than the pseudo-critical temperature. Using the two-layer model, which can use a smaller mesh near the pseudo-critical temperature will be considered in the near future.
View full abstract
-
Fumihisa Kano, Yumiko Tsuchiya, Norihisa Saito, Akio Shioiri, Shigeki ...
Article type: Article
Pages
181-182
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
CONFERENCE PROCEEDINGS
RESTRICTED ACCESS
The SCPR is expected to be an innovative nuclear power system with considerably higher thermal efficiency and smaller specific volume. Material compatibility for core components, in particular fuel claddings, is thought to be a key factor for the viability of SCPR Material screening is performed through literature survey, simulated irradiation tests, corrosion tests, SCC tests, and mechanical tests under SCPR conditions. Candidate materials in this study are selected from materials used in three industrial fields : fossil power plant, waste processing plant and nuclear power plant. This paper describes the results of electron beam irradiation tests for the assessment of irradiation resistance and SCC tests with austenitic stainless steels. Simulated irradiation tests were performed for austenitic stainless steels, nickel base alloys and titanium alloys at 563K, 723K and 823K up to five displacement per atom (dpa) using a high-energy transmission electron microscope (HVTEM) with the electron beam of 1000kV. The susceptibility to intergranular stress corrosion cracking (IGSCC) was evaluated by slow strain rate tests (SSRTs), which were performed using an SCPR test loop at the strain rate of 4X(10)^<-7>/s, the temperatures from 563 to 823K and the pressure of 25MPa in high purity water with 8 ppm dissolved oxygen (DO). The results for sensitized Type 304 SS indicated that the IGSCC susceptibility decreased with increasing temperature. It was found the upper limit of IGSCC susceptibility existed for sensitized type 304 SS at around 673K, above which IGSCC susceptibility disappeared.
View full abstract
-
Shigeki KASAHARA, Jiro KUNIYA, Kumiaki MORIYA, Norihisa SAITO, Shigeno ...
Article type: Article
Pages
183-184
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
CONFERENCE PROCEEDINGS
RESTRICTED ACCESS
One of the major technical issues is development of materials for the supercritical-water cooled power reactor (SCPR) fuel claddings and core components. The materials will be used under the high-pressurized water in the temperature range of 573K-823K. Therefore, they should involve good properties of mechanical integrity, corrosion resistance and radiation damage. Technical issues of the material development were clarified from the literature survey of the material technologies for the fields of supercritical pressure fossil fired power plants, supercritical-water waste processing plants, and nuclear power plants. After that, test materials were nominated from austenitic and ferritic stainless steels, Ni-based alloys and Ti-based alloys. Tensile tests at 550℃ were conducted to evaluate the mechanical integrity of the materials under high temperature environments. General corrosion tests and 1 MeV electron irradiation tests were carried out under the SCPR core conditions, which were expected from the current research of the SCPR core design. The database will be applied to the screening of the most promising materials for the fuel claddings and to improvement of the SCPR system design. In this paper, the framework of the material development is introduced, and the data from general corrosion tests and electron irradiation tests are presented.
View full abstract
-
Michio SADATOMI, Akimaro KAWAHARA, Tsukasa KUNO
Article type: Article
Pages
185-186
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
CONFERENCE PROCEEDINGS
RESTRICTED ACCESS
The purpose of this study is to describe analytically two-phase void drift phenomena in a 2×3 rod bundle channel simulating BWR fuel rod bundle. For that, a subchannel analysis code, which was developed by the present authors and based on a two-fluid model, was used, and prediction of gas and liquid flow redistribution due to void drift between subchannels in the 2×3 rod bundle channel was conducted. In the code, a void settling model for evaluating the void drift effect was incorporated with usual conservation equations of mass and momentum. From a comparison, it was found that the subchannel analysis code can predict well the data on subchannel flow and void fraction variations in the 2×3 rod channel if an appropriate correlation was employed to evaluate wall and interfacial friction forces.
View full abstract
-
Michitsugu Mori, Kenichi Tezuka, Yuuichi Kagami, Hideaki Tezuka
Article type: Article
Pages
187-188
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
CONFERENCE PROCEEDINGS
RESTRICTED ACCESS
Dry-out and rewetting on fuel rods in a reactor core, possibly observed during the events of pump trip or reactor power increase etc., are significant phenomena from the viewpoints of securing the integrity of a fuel rod and safety evaluation on MCPR in the design. The two-phase flow boiling visualization experiments of dry-out and rewetting processes by a high-speed digital movie were successfully carried out under BWR rated-operating condition of ∿7MPa and ∿286℃ in the present work; on the other hand, these visualization tests could be found only under the atmospheric pressure conditions so far. The tests were carried out using the thermal-hydraulic experimental loop of Tokyo Electric Power Co., Inc. (TEPCO), which enables us to directly observe the two-phase flow boiling, dry-out and rewetting phenomena under the BWR rated-operating conditions of ∿7MPa and ∿286℃. The observations by a high-speed digital movie, measurements of void fraction increase by optical-fiber void probes and rods' surface temperature soaring and steep diving by thermocouples brought us incontrovertible evidences of the occurrence of rewetting just after dry-out in transients.
View full abstract
-
Masaki MISAWA, Akio SUZUKI, Naoki ICHIKAWA, Masaharu KURODA, Akihiko M ...
Article type: Article
Pages
189-190
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
CONFERENCE PROCEEDINGS
RESTRICTED ACCESS
This paper describes the instanteneous cross section void fraction measurement in a double cylinder natural circulation test facility using a wire-mesh sensor built in the vessel cross sections. The inner and outer cylinders with their inner diameters of 0.49m and 0.39m, respectively, were placed co-centrically to simulate basic natural circulation flow to be developed around a chimney of a natual circulation nuclear reactor for next generation. Air was uniformly introduced from the bottom plate of the inner cylinder to drive upward flow in the chimney and downward flow in the downcomer. The natural circulation velocity of water remained almost unchanged while air flow rate was increased. This is mainly due to increased amount of bubbles trapped in the downward flow in the downcomer region.
View full abstract
-
Akihiko MINATO, Takuji NAGAYOSHI, Masaya OHTSUKA, Masaki MISAWA, Akio ...
Article type: Article
Pages
191-192
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
CONFERENCE PROCEEDINGS
RESTRICTED ACCESS
Natural circulation type boiling water reactors are expected as promising next generation nuclear reactors, because recirculation system is reduced and loss of coolant event is mitigated. Three-dimensional gas-liquid two-phase flow in the chimney above the core is important for developing natural circulation flow rate through void fraction profile and carry under bubbles into the downcomer. The experiments were carried out using the test section with double cylinders imitating the pressure vessel and the chimney of a natural circulation reactor. Numerical analysis of the experiments have been performed using the extended two-fluid model, which can treat large scale interface directly and small scale interface with the averaged parameters as conventional two-fluid model. Transient gas-liquid two-phase flow after air injection in the bottom cross-section of the inner cylinder are calculated. Predicted natural circulation velocity in the downcomer is overestimated by 10% compared with experimental data.
View full abstract
-
Tadahiko SUZUTA, Kikuo NAKAMURA, Kazunori INOUE, Seiji ARITA, Jyunji O ...
Article type: Article
Pages
193-194
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
CONFERENCE PROCEEDINGS
RESTRICTED ACCESS
The safety concept of APWR+ on small LOCA event is adopted to use the Steam Generator (SG) for decay heat removal. Therefore, it is very important to be maintained the natural circulation in primary system on small LOCA event to transfer decay heat from core to SG. The natural circulation of two phase flow with non-condensable gas may be hindered by the siphon brake in the u-bend region of SG. This paper focuses the siphon brake phenomena on U-bend tube, and report the air-water and steam-water with non-condensable gas test results. Also, the two phase natural circulation code CANAC3-3D is verified to use these data.
View full abstract
