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| 1.
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中村, 卓人 ; 小林, 佳弘 ; 古畑, 朋彦 ; 新井, 雅隆
概要:
application/pdf<br />Journal Article<br />Nano meter size particulate matter (nano-PM) and polycyclic aromatic hydrocarbons (PAHs) have harmful effects for human health. It was thought that PAHs were a precursor of nano-PM. Then
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fundamental information of PAHs behavior in combustion process has been required to establish reduction technologies for nano-PM emission. In this paper, PAHs concentration, PM composition, and number concentration of PM in diffusion flames of methane (CH_4) and propane (C_3H_8) were investigated. As the result, benzene and toluene formed from fuel (methane or propane) had the two peaks at upstream and at downstream of PAHs-soot transition region in the flames. Moreover, concentration of PAHs formed from propane was higher than that formed from methane. In addition, both of soot and SOF compositions in PM formed from propane flame showed higher concentrations than those in methane flame.
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| 2.
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森田, 真一 ; 渡辺, 直樹 ; 古畑, 朋彦 ; 新井, 雅隆
概要:
application/pdf<br />Journal Article<br />Six-stroke diesel engine proposed here has six processes in one cycle, i.e. intake, 1st compression, 1st combustion, 2nd compression, 2nd combustion and exhaust. By the direct EGR in the 2nd
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combustion process, NO emission could be expected to decrease. However, much Soot was exhausted by a weak mixing in the 2nd combustion process. A high pressure injection with a common rail was introduced into the engine to improve the mixing in the second combustion process. As a result, more NO was exhausted while Soot was decreased due to better mixing. In this study, to decrease NO and Soot simultaneously, two stage fuel injection was applied to the 1st combustion. When the main injection timing for the 1st combustion process was extremely delayed, NO and Soot were decreased. It was considered that NO reduction was due to the 1st combustion of low temperature and EGR effect in the 2nd combustion. Also, Soot reduction was due to a relatively long ignition delay for the 2nd combustion
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| 3.
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山本, 知恵美 ; 内野, 寿一 ; 古畑, 朋彦 ; 新井, 雅隆
概要:
application/pdf<br />Journal Article<br />Nanometer size particulate matter (Nano-PM) emitted from diesel engine has been received many anxieties due to its harmful potential for health. The objective of this study is to develop a
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standard Nano-PM generator using liquid fuels, and to investigate the relationship between the characteristics of PM and operation parameters of the generator. A fundamental pool flame of diesel fuel was used for generation of Nano-PM. Scanning Mobility Particle Sizer (SMPS3034) was used to measure the size distribution of PM, and the components of PM were analyzed using a combustion type exhaust gas analyzer (MEXA-1370PM). Thermal diluter was used to investigate the heating effect on size distribution of PM. Main parameters of the PM generator were height and pattern of diffusion flame. Two types of diffusion flame were formed on a fuel pool. One is a small flame where the flame tip was closed and no visible soot was observed. The other was an open tip flame that emitted visible soot from its tip. As for the size distribution of PM, peak diameter increased gradually with an increase of fuel consumption rate. Main component of Nano-PM exhausted from a closed flame was SOF, however dry soot was the main component of open flame. Under hot thermal dilution, number of large particles decreased but number of small particles increased.
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| 4.
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佐々木, 徹 ; 天野, 俊輔 ; 渡辺, 哲也 ; 古畑, 朋彦 ; 新井, 雅隆
概要:
application/pdf<br />Journal Article<br />A low NO_x combustor for kerosene-fueled micro gas turbine based on a new concept was proposed. The combustor consisted of primary and secondary combustion zones, and they were
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connected by a throat. A swirler was set between the primary and secondary combustion zones. In order to enhance recirculation of burned gas in the primary combustion zone, combustion air was introduced through the swirler and forced to flow upward to the combustor bottom. In this study, fundamental combustion characteristics such as lean combustion limit, exhaust gas composition and combustion gas temperature were measured using three fuel atomizers which rated flow rates were 3.0 gallon/h, 4.5 gallon/h and 6.0 gallon/h respectively. It was shown that the combustion stability and emission characteristics in the case of 3.0 gallon/h nozzle were superior to those in other cases. Further, gas velocity in the primary combustion zone was measured by Leaser Doppler Anemometer (LDA) and behavior of the recirculation of burned gas was investigated
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| 5.
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小林, 佳弘 ; 天谷, 賢児 ; 古畑, 朋彦 ; 新井, 雅隆
概要:
application/pdf<br />Journal Article<br />Nano meter size particulate matter (PM) and polycyclic aromatic hydrocarbons (PAHs) have harmful effects for human health. Investigations of fundamental characteristic of formation behavior of
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PAHs in combustion process were required for the reduction of nano-PM emission. In this paper, PAHs characteristics in diffusion flames of paraffin fuels were investigated using laser diagnostic and gas sampling methods. Methane (CH_4), propane (C_3H_8) and hexane (C_6H_<14>) were used as the test fuels. A laser induced fluorescence (LIF) method was used to obtain the spatial distributions of PAHs which were precursor molecules of soot. Spatial distributions of soot were also measured by a laser induced incandescence (LII) method. A transition region from PAHs to soot was defined from the results of LIF and LII. Further, PAH concentrations in the test flames were measured using a gas chromatography (GC). Profiles of PAHs concentrations of test flames were compared. As the results, it was found that the low carbon number fuels such as propane and methane are remained to some fuel at downstream part. And, these some fuels were changed to large PAHs at downstream part.
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| 6.
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佐々木, 徹 ; 天野, 俊輔 ; 渡辺, 哲也 ; 世取山, 幸作 ; 古畑, 朋彦 ; 新井, 雅隆
概要:
application/pdf<br />Journal Article<br />A low NO_x combustor for kerosene-fueled micro gas turbine based on a new concept was proposed. The combustor consisted of primary and secondary combustion zones, and they were
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connected by a throat. A swirler was set between the primary and secondary combustion zones. In order to enhance recirculation of burned gas in the primary combustion zone, combustion air was introduced through the swirler and forced to flow upward to the combustor bottom. In this study, effects of configuration of primary combustion zone on combustion gas flow in it were investigated. The length of primary combustion zone, swirler vane angle, diameter of throat and height of guide vane were changed independently from the standard configuration. Distributions of gas flow in the primary combustion zone were measured with LDA. The relation between combustion stability and the distributions of gas flow was discussed, and it was found that appropriate combustion gas recirculation in the primary combustion zone was necessary to keep combustion stability high.
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| 7.
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星野, 浩之 ; 満山, 陽平 ; 齊藤, 正浩 ; 古畑, 朋彦 ; 新井, 雅隆
概要:
application/pdf<br />Journal Article<br />In order to reveal the soot removal mechanism in Electric Diesel Particulate Trap (E-DPT), mechanism of soot trapping and re-burning of soot particles in exhaust gas was investigated using
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one channel electric diesel particulate trap (1 channel E-DPT). The E-DPT is capable to trap soot particles by applying DC electric field between electro-plates. The results showed that soot particles like a whisker grew up from negative electrode side toward positive one. Soot particles trapped on the plates formed many soot bridges in narrow space between electro-plates. Formation of soot particles depended on electric intensity. In the condition of F=200 kV/m, lumps of soot were observed instead of whisker like soot bridges and soot trapping and soot re-burning were balanced. Ignition of the soot lump was occurred at the contact point between the lump and electro-plate, however re-burning of whole the lump was rarely observed. Remained soot drifted to down stream. It is thought that many remained soot particles were discharged from the E-DPT. Incomplete reburning of soot lump caused soot removal efficiency deterioration of E-DPT. In the case of narrow space and high electric intensity (F=600kV/m, L=0.5mm), however, soot bridge re-burning was main phenomenon and soot lump re-burning was controlled
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| 8.
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山本, 克臣 ; 中路, 智晴 ; 古畑, 朋彦 ; 新井, 雅隆
概要:
application/pdf<br />Journal Article<br />In order to reduce CO_2 emission from combustion systems with fossil fuel, it
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is necessary to increase thermal efficiency of them. Heat recovery from flue gas is very effective in increasing thermal efficiency of a small furnace. Through this heat recovery, temperature of flue gas decreased with increasing a recovery amount of heat. It is feared that a decrease of temperature newly causes secondary condensed particles in a stack, and these particles become a problem in future. In this study, therefore, particulate matters (PM) in a flue gas stream from a spray combustion furnace were sampled and their compositions and size distributions were measured. As the result, it was shown that the mass of volatile matters in PM and the number of particle gradually increased along the stack. It was found that, moreover, the condensation of volatile matters probably occurred under the condition that flue gas temperature was below 460℃. From these results, it was clear that secondary condensed particles were formed in the stack.
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| 9.
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倉持, 大輔 ; 川口, 知宏 ; 古畑, 朋彦 ; 新井, 雅隆
概要:
application/pdf<br />Journal Article<br />Ignition and combustion characteristics of diesel spray impinged on an extrude
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d wall, which was a top of cylindrical column, were experimentally investigated. Appearance positions of OH and C_2 radical luminosities and luminous flame kernel were stereoscopically observed using a two-way fiber optical system. The extruded column was fixed in a high temperature and high pressure combustion chamber. A diesel spray was impinged vertically to the extruded wall. Effects of cylindrical column diameter (D=5,10,15mm, ∞(flat wall)) on ignition and combustion characteristics were investigated. As the result, appearance position of OH luminosity was observed near the spray tip except for D=∞ (flat wall). The maximum volume of luminous flame impinged on the extruded wall was strongly influenced by the diameter of the column. In a condition of low-ambient temperature, the maximum volume of blue flame on the extruded column of 10 mm diameter was larger than those on other columns.
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| 10.
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小林, 佳弘 ; 天谷, 賢児 ; 古畑, 朋彦 ; 新井, 雅隆
概要:
application/pdf<br />Journal Article<br />In this study, formation mechanisms of PM (particulate matter) and its precursor (PAHs (polycyclic aromatic hydrocarbons)) were investigated as a fundamental PM study of diesel fuel
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combustion. A laminar diffusion flame of diesel fuel at a small pool-wick combustion equipment was used as the test flame. Spatial distributions of PAHs and soot in the flame were measured by a laser induced fluorescence (LIF) and a laser induced incandescence (LIT) methods. Emission spectra of PAHs fluorescence were analyzed by a spectroscope. Since the peak wavelength of the LIF spectrum of PAHs could be described as a function of the carbon number of PAHs, the molecular size of PAHs could be estimated. PAH species in the flame were measured using a gas chromatography (GC). LIF and GC data were compared for understanding the transition behavior from PAH to soot. These results suggested that the PAHs molecules rapidly grew up to the soot particles at nucleation area of PM. It was confirmed that relatively small PAHs species such as benzene and toluene existed in sooting region, however, the larger PAHs such as fluorine and pyrene could not be observed in the sooting region.
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