JSME International Journal Series B Fluids and Thermal Engineering
Online ISSN : 1347-5371
Print ISSN : 1340-8054
ISSN-L : 1340-8054
Volume 47 , Issue 2
Special Issue on International Conferences on Power and Energy System
Showing 1-37 articles out of 37 articles from the selected issue
PAPERS
  • Fumiyoshi KIMURA, Tatsuo TACHIBANA, Kenzo KITAMURA, Tsutomu HOSOKAWA
    2004 Volume 47 Issue 2 Pages 156-161
    Published: 2004
    Released: January 25, 2005
    JOURNALS FREE ACCESS
    Natural convective flows of water induced around heated vertical cylinders have been investigated experimentally. Special interests were paid to the influences of cylinder diameter on the turbulent transition and also on the local heat transfer characteristics of the cylinders. The diameters of the cylinders were varied systematically from 10 to 165mm. Visualizations of the flows around the cylinder and of the surface temperatures of the heated cylinders have been carried out to determine the onset of turbulent transition. The result showed that the onset of turbulent transition shifts toward downstream with decreasing the cylinder diameters, when, in particular, the diameters are smaller than 60mm. Moreover, the local heat transfer coefficients of the cylinder show marked increase in the both regions of laminar and turbulent flows with decreasing the diameters.
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  • Shixue WANG, Yoshio UTAKA
    2004 Volume 47 Issue 2 Pages 162-167
    Published: 2004
    Released: January 25, 2005
    JOURNALS FREE ACCESS
    The condensation heat transfer characteristic curves for a ternary vapor mixture of water, ethanol and air (or nitrogen) under several ethanol concentrations and relatively low concentrations of air (or nitrogen) were measured. The effect of non-condensable gas on several different domains in the condensation curves was discussed. The effect of non-condensable gas in the domains controlled by the diffusion resistance and the filmwise condensation was not notable; whereas that in the domain dominated by the condensate resistance of dropwise mode was remarkable. Moreover, variations due to changes in non-condensable gas concentration of several characteristic points representing the curves were discussed.
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  • Toru MITSUTAKE, Fumihisa KANO, Tetsuo OOSATO, Akio SAYANO, Miyuki AKIB ...
    2004 Volume 47 Issue 2 Pages 168-172
    Published: 2004
    Released: January 25, 2005
    JOURNALS FREE ACCESS
    Under forced convection and atmospheric pressure conditions, heat transfer characteristics were studied using an annulus channel of a heater rod with highly-wettable surface. Improvement of phase change heat transfer under boiling and condensation process requires that either liquid heated or vapor cooled can contact a heat transfer surface effectively, but either a vapor layer or a liquid film can be formed repeatedly on the surface during boiling and condensation processes. As oxide semiconductor materials are known to be highly wettable, TiO2 was coated on a heater rod surface. The Leidenfrost temperature for the TiO2 coated surface was higher than that for the uncoated surface. Under mass flux conditions from 600 to 1700kg/m2s, the heater rod surface temperature at variable power conditions was measured. A higher heat flux at the point where the forced convection vaporization started and a larger critical heat flux were observed for the TiO2 coated surface than that for the uncoated surface.
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  • Satoshi GAMOU, Koichi ITO, Ryohei YOKOYAMA, Shu YOSHIDA
    2004 Volume 47 Issue 2 Pages 173-179
    Published: 2004
    Released: January 25, 2005
    JOURNALS FREE ACCESS
    An optimal planning method of system structure is proposed to determine kinds, numbers and capacities of equipment for an energy supply system installed in commercial and public buildings from economic viewpoint. In this method, they are determined together with maximum contract demands of utilities such as electricity and natural gas so as to minimize the annual total cost in consideration of system's annual operational strategies corresponding to seasonal and hourly energy demand requirements. A numerical study is carried out for an office building with total floor area of 15000m2. Through the study, the following are clarified: (a) the optimal system structure for the office building; (b) the economic effects of the optimal system compared to other typical energy supply systems; (c) the influence on the optimal system structure of the future efficiency improvement and initial capital cost reduction of equipment.
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  • Michitaka IKEDA, Hisao MAKINO, Hideki MORINAGA, Koichi HIGASHIYAMA
    2004 Volume 47 Issue 2 Pages 180-185
    Published: 2004
    Released: January 25, 2005
    JOURNALS FREE ACCESS
    Because of large recoverable reserves, sub-bituminous coal is an important energy resources. The disadvantage of sub-bituminous coal is that it contains more than 20% moisture. This makes ignition less efficient. And combustion flame became diffused. Both emissions of NOx and unburned carbon in fly ash become high. We have already shown that these emissions can be reduced by adjusting the air injection conditions from the burner to better suit sub-bituminous coal combustion. However, the reduction is insufficient compared with bituminous coal combustion. In this investigation, influence of two-stage air injection conditions on NOx and unburned carbon concentration in fly ash was studied and the optimum air injection conditions necessary in order to reduce those emissions were clarified.
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  • Yoshizo SUZUKI, Tomoyuki NOJIMA, Akihiko KAKUTA, Hiroshi MORITOMI
    2004 Volume 47 Issue 2 Pages 186-192
    Published: 2004
    Released: January 25, 2005
    JOURNALS FREE ACCESS
    A conceptual design of an energy recovering system from sewage sludge was proposed. This system consists of a pressurized fluidized bed combustor, a gas turbine, and a heat exchanger for preheating of combustion air. Thermal efficiency was estimated roughly as 10-25%. In order to know the combustion characteristics of the sewage sludge under the elevated pressure condition, combustion tests of the dry and wet sewage sludge were carried out by using laboratory scale pressurized fluidized bed combustors. Combustibility of the sewage sludge was good enough and almost complete combustion was achieved in the combustion of the actual wet sludge. CO emission and NOx emission were marvelously low especially during the combustion of wet sewage sludge regardless of high volatile and nitrogen content of the sewage sludge. However, nitrous oxide (N2O) emission was very high. Hence, almost all nitrogen oxides were emitted as the form of N2O. From these combustion tests, we judged combustion of the sewage sludge with the pressurized fluidized bed combustor is suitable, and the conceptual design of the power generation system is available.
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  • Akihisa ASAI, Kazuhiro IZAKI, Youichi EGAMI, Kouhei TSUJI, Shunji KUMA ...
    2004 Volume 47 Issue 2 Pages 193-199
    Published: 2004
    Released: January 25, 2005
    JOURNALS FREE ACCESS
    Karita Power Station New Unit 1, which started commercial operation on July 3, 2001, has adopted the new power generation system PFBC, Pressurized Fluidized Bed Combustion, a combined cycle generation system. The system boasts high thermal efficiency, excellent environmental characteristics and compact size. Output from the steam turbine generator and gas turbine generator is 290MW and 75MW, respectively, with total output adjusted to 360MW, making the unit the largest PFBC plant in the world. In October 2002, combustion tests were conducted using an anthracite coal from Yangquan; and in April 2003, a world record was achieved for continuous operation hours of a PFBC plant. This paper focuses on the outline and operation status of Karita New Unit 1.
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  • Kwang-Jae MYONG, Motoyuki ARAI, Tomoyuki TANAKA, Jiro SENDA, Hajime FU ...
    2004 Volume 47 Issue 2 Pages 200-206
    Published: 2004
    Released: January 25, 2005
    JOURNALS FREE ACCESS
    In this study, droplet atomization and vaporization characteristics with multi-component fuel were investigated by experimental and numerical simulation methods. Spray characteristics of multi-component fuel including spray cone angle, spray angle and spray tip penetration were analyzed from shadowgraph imaging. Numerical simulation to investigate spatial distribution of fuel-vapor concentration of each component within multi-component fuel was implemented in KIVA code. Vaporization process was calculated by a simple two-phase region which was approximated by modified saturated liquid-vapor line. Experimental results show that spray cone angle and spray angle become larger increasing in mass fraction of low boiling point component. And spray tip penetration becomes shorter with increasing in mass fraction of low boiling point component in vaporizing spray during that is same on every mixed fuel in non-vaporizing spray. From numerical simulation results, temporal and spatial distribution of each fuel vapor concentration was found to be stratification.
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  • Tetsuji SEKO, Ryosuke MATSUMOTO, Yoshitomo SHINTANI, Isao ISHIHARA, Ma ...
    2004 Volume 47 Issue 2 Pages 207-213
    Published: 2004
    Released: January 25, 2005
    JOURNALS FREE ACCESS
    An advanced-type compact water-tube boiler has been designed on the basis of the new concept of cooling flame by water-tube bank in the furnace, and is referred to as “tube-nested combustor”. It realized drastic reduction in boiler size as well as in the NOx emission. In this present study, aiming at further improvement of boiler efficiency and reduction of NOx emission, the combustion characteristics in the furnace were investigated by using the test boiler of 0.5t/h steam output. Experimental results indicated that the NOx formation was restricted in the narrow area close to the burner exit, and that the CO-concentration decreased drastically with the combustion gas stream through the tube-bank. These facts were closely related to the experimental evidence of the cross-sectional distribution of gas temperature being rather uniform owing to the agitation by the tube-bank. These experimental results verified the soundness of the boiler design and, in addition, gave relevant information on local combustion characteristics available for the R&D of the next generation tube-nested combustor.
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  • Ryosuke MATSUMOTO, Isao ISHIHARA, Mamoru OZAWA, Keizo IMAHORI
    2004 Volume 47 Issue 2 Pages 214-220
    Published: 2004
    Released: January 25, 2005
    JOURNALS FREE ACCESS
    This study focuses on fundamental characteristics of DME (Dimethyl Ether) combustion, aiming at the development of low-NOx combustion. DME is one of the most promising new alternative fuels owing to its cleanness of the exhaust gas and wide applications. Combustion experiments using a diffusion burner were conducted for characterizing DME through the comparison with the results of LPG and 13A-city gas. Experimental results demonstrated a high potential of DME for a boiler and a gas-turbine fuel. DME has a wide stable-combustion range compared with those of the other fuels. In this study, the concept of the low-NOx combustion, referred to as the tube-nested combustion, was applied to the DME combustion. This tube-nested combustor consists of tube banks to cool the burning flame leading to NOx reduction. Then, the NOx emission of the DME combustion was successfully reduced to a level suitable for practical applications.
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  • Hidenori KOSEKI
    2004 Volume 47 Issue 2 Pages 221-227
    Published: 2004
    Released: January 25, 2005
    JOURNALS FREE ACCESS
    This paper describes an investigation conducted on flame stability and exhaust emissions from a turbulent diffusion combustor, fueled with low-calorific gas, for a small-scale fuel cell. It is important to maintain flame stability in the combustor, even under lean fuel conditions, and to suppress CO emission in the exhaust gas. An imitation off-gas, in which hydrogen and methane were diluted by adding nitrogen, with Wobbe indices ranging from ca. 4400-8700, corresponding to the fuel utility ratio of 90%-60%in the fuel cell, was supplied to the combustor, and the blow-off limits, CO, and NOx emissions were experimentally investigated. The results show that the blow-off excess air ratios increases with an increasing Wobbe index and with decreasing fuel input to the combustor, and that they are proportional to the hydrogen concentration in the fuel to the power of 0.5-1.0. In addition, it was found that the Damköhler numbers at blow-off limits decreased with decreasing fuel input and with increasing Wobbe indices, and that the product of (SS / V·M)A[H2][O2]0.5 was constant at blow-off limits. Furthermore, NOx emissions from the combustor were low, less than 20ppmV (O2=0%), it was also found that the apparent activation energy of NOx emission derived from Arrhenius plots was almost equal to that of prompt NO in the combustion of imitation off-gas.
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  • Hiroyuki INOUE, Hirofumi DAIGUJI, Eiji HIHARA
    2004 Volume 47 Issue 2 Pages 228-234
    Published: 2004
    Released: January 25, 2005
    JOURNALS FREE ACCESS
    A catalyst layer is one of the key elements in polymer electrolyte membrane fuel cells (PEMFC). Improvements in the performance of a membrane electrode assembly (MEA) for PEMFC are much influenced by an electrochemically active surface area in a catalyst layer. But the relation between the structure of a catalyst layer and the cell performance has not been clarified yet. In the present study, catalyst layers with different structure and composition were fabricated, and the structural properties of catalyst layers, such as thickness and roughness, and the polarization curves were measured. The experimental results suggested that there is an optimum mass ratio of electrolyte in a catalyst layer for the cell performance, and the thickness and roughness of a catalyst layer change significantly at the optimum mass ratio.
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  • Yukio HISHINUMA, Takemi CHIKAHISA, Fumio KAGAMI, Tomohiro OGAWA
    2004 Volume 47 Issue 2 Pages 235-241
    Published: 2004
    Released: January 25, 2005
    JOURNALS FREE ACCESS
    At temperatures below freezing, air humidity becomes lower and produced water at the cathode freezes on the surface of catalyst, and it is difficult to start a PEFC (Polymer Electrolyte Fuel Cell) at a cold district. The object of the work is to study the performance of the fuel cell below the freezing point by experiments and simulation. To investigate the characteristics of the starting of a temperature below freezing the performance of a single cell was measured at temperatures from -3 to -25°C and pressures from 1 to 2 atm. The results of the experiments and simulation indicate that the performance of a PEFC decreases at higher current densities and pressures, and lower cell temperatures because of ice more produced on the reactive area of the cathode. To maintain the cell performance below freezing point, it is effective to adjust the current densities and gas flow rate to balance the produced and removed water. However at -5°C, heat generated in the fuel cell is effective to warm the cell and make self-starting possible. These results shows that it is necessary to heat the cell with an additional heat source in order to start the fuel cell below -5°C.
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  • Keisuke TAKESHITA, Yoshiharu AMANO, Takumi HASHIZUME, Toshitaka TAKEI, ...
    2004 Volume 47 Issue 2 Pages 242-248
    Published: 2004
    Released: January 25, 2005
    JOURNALS FREE ACCESS
    The performance of the rectifying column affects the coefficient of performance (COP) of an ammonia absorption refrigerator. Ammonia mass fraction of refrigerant is one of the key parameters indicating the performance of the rectifying column. We propose a method to estimate the refrigerant mass fraction with mass and energy balance equations around the separator at the inlet of the evaporator, and describe the results of experiments which measured the refrigerant mass fraction by sampling from the refrigerant receiver. Throughout these investigations, the refrigerant mass fraction turned out to be lower than the expected value calculated from the condition of dry-saturated vapor at the top of the rectifying column. The refrigerant mass fraction can be estimated within an accuracy of 0.3% by the estimation method based on mass and energy balance equations.
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  • Hirohide FURUTANI, Nikolaj UZUNOW
    2004 Volume 47 Issue 2 Pages 249-255
    Published: 2004
    Released: January 25, 2005
    JOURNALS FREE ACCESS
    Recovery of waste heat is an effective means of achieving energy conservation, and the total amount of industrial waste heat is still notable. However, the value of waste heat as an energy source is low (low exergy). Its utilization therefore requires larger recovery systems with increased costs. The concept of introducing a second, high-quality heat source in the form of H2-O2 combustion in order to improve the system's performance is presented here. System analysis of the combination effect (higher output from combined than from separate sources) was conducted. The investigation results show that the systems under consideration have the potential for significant merits under moderate conditions. The proposed combination of low- and high-quality heat sources also permits reductions in the system size and cost.
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  • Yoshiharu TSUJIKAWA, Ken-ichi KANEKO, Jun SUZUKI
    2004 Volume 47 Issue 2 Pages 256-260
    Published: 2004
    Released: January 25, 2005
    JOURNALS FREE ACCESS
    Solid oxide fuel cell (SOFC) has been extensively developed in many countries as an ultra-high efficient energy converter. Such high temperature fuel cell can be operated as a hybrid system of integrating of turbo machinery. A major decision is whether to place the cell stack in pressurized or unpressurized section. This paper discusses the exhaust energy recovery from fuel cells by use of turbo machines under unpressurized conditions, working with inverted Brayton cycle in which turbine expansion, cooling by heat exchanger and draft by compressor are made in an open cycle mode. It is denoted as “atmospheric pressure turbine (APT)”.
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  • Kazuhiko KUNITOMI, Shoji KATANISHI, Shoji TAKADA, Takakazu TAKIZUKA, X ...
    2004 Volume 47 Issue 2 Pages 261-267
    Published: 2004
    Released: January 25, 2005
    JOURNALS FREE ACCESS
    The GTHTR300 aiming at electric generation with its thermal efficiency of 46% is a safe and economically competitive HTGR in 2010s. A helium gas turbine system connected with the reactor is designed based on existing technologies developed for fossil gas turbine systems. However, there are some uncertainties in performance of a helium gas compressor, electric magnetic bearings and control system. In order to confirm these technical uncertainties, a 1/3 scale model of the compressor and 1/3 scale magnetic bearings will be manufactured and tested in the simulated condition of the GTHTR300. Also, a 5MW helium gas loop composed of the gas turbine system and electric heaters will be constructed, and control performance during startup and shutdown, and off- normal transients such as loss of off site loads will be tested to streamline the gas turbine system. This paper describes R&D plans focusing on the 1/3 scale compressor model test as well as unique design features of the GTHTR300.
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  • Jie LIU, Seiichi KOSHIZUKA, Yoshiaki OKA
    2004 Volume 47 Issue 2 Pages 268-276
    Published: 2004
    Released: January 25, 2005
    JOURNALS FREE ACCESS
    A non-equilibrium, multi-phase, multi-component code PROVER-I is developed for propagation phase of vapor explosion. A new thermal fragmentation model is proposed with three kinds of time scale for modeling instant fragmentation, spontaneous nucleation fragmentation and normal boiling fragmentation. The role of fragmentation mechanisms is investigated by the simulations of the pressure wave propagation and energy conversion ratio of ex-vessel vapor explosion. The spontaneous nucleation fragmentation results in a much higher pressure peak and a larger energy conversion ratio than hydrodynamic fragmentation. The instant fragmentation gives a slightly larger energy conversion ratio than spontaneous nucleation fragmentation, and the normal boiling fragmentation results in a smaller energy conversion ratio. The detailed analysis of the structure of pressure wave makes it clear that thermal detonation exists only under the thermal fragmentation circumstance. The vapor explosion is weak in larger vapor volume fraction conditions. In a large-scale vapor explosion, the hydrodynamic fragmentation is essential when the pressure wave becomes strong, so a small energy conversion ratio is expected.
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  • Muhammad Hadid SUBKI, Masanori ARITOMI, Noriyuki WATANABE, Moon Ki CHU ...
    2004 Volume 47 Issue 2 Pages 277-286
    Published: 2004
    Released: January 25, 2005
    JOURNALS FREE ACCESS
    The purpose of the study is to experimentally investigate driving mechanism of major instabilities simulated in a natural circulation experimental loop, under a predetermined range of system operating pressure and inlet subcoolings. Pressure range of 0.1 up to 0.7MPa, input heat flux range of 0 up to 577kW/m2, and inlet subcoolings of 5, 10 and 15K respectively, are applied in the experiments. The objective of the study is to formulate a rational startup procedure, in which major thermohydraulic instabilities can be detected and prevented. The study clarifies that four (4) kinds of thermohydraulic instability might occur even up to a higher pressure of 0.7MPa. The instabilities' sequence is as follows: (1) geysering induced by condensation accompanied by flashing, (2) oscillation induced by hydrostatic head fluctuation, (3) density wave oscillations, and (4) flashing accompanying those instabilities. The experiments confirmed that the geysering region gets narrower and suppressed with the increased system pressure. With chimneys, natural circulation can be achieved reliably and more easily. However, the flashing in the chimney cannot be avoided at low system pressure. Stable two-phase natural circulation can be established if the system pressure is increased beyond 0.7MPa, after the high frequency density eave oscillation thoroughly suppressed. The experiments were analyzed based on frequency domain of each instability phenomenon.
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  • Akihiko MIURA, Akiko MATSUO, Toshiharu MIZUKAKI, Takuya SHIRAISHI, Go ...
    2004 Volume 47 Issue 2 Pages 287-292
    Published: 2004
    Released: January 25, 2005
    JOURNALS FREE ACCESS
    This paper presents the results of an optical experiment which is carried out to measure the pressure and to observe the wave propagations when an explosion occurs in a model of a nuclear facility for preventing and mitigating the serious damage of nuclear facility. Numerical simulation is also performed to compare the phenomena in a model of nuclear facility. Nuclear facility is simulated as the several closed rooms in these experiments and simulations, because the nuclear facility is composed of many closed rooms. As a result, typical tendencies of pressure history are obtained, and it is confirmed that the explosion which occurs in a closed space is reflected in the complexity at the walls and interfered mutually with progressing waves. Finally, experimental results are compared with a numerical simulation. It is confirmed that the results of a numerical simulation show a good agreement with experimental results.
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  • Hidesada TAMAI, Masatoshi KURETA, Hiroyuki YOSHIDA, Hajime AKIMOTO
    2004 Volume 47 Issue 2 Pages 293-298
    Published: 2004
    Released: January 25, 2005
    JOURNALS FREE ACCESS
    The reduced-moderation water reactor (RMWR) consists of several distinctive structures; a triangular tight-lattice configuration and a double-flat core. In order to design the RMWR core from the point of view of thermal-hydraulics, an evaluation method on pressure drop characteristics in the rod bundles at the tight-lattice configuration is required. In this study, calculated results by the Martinelli-Nelson's and Hancox's correlations were compared with experimental results in 4×5 rod bundles and seven-rod bundles. Consequently, the friction loss in two-phase flows becomes smaller at the tight-lattice configuration with the hydraulic diameter less than about 3mm. This reason is due to the difference of the configuration between the multi-rod bundle and the circular tube and due to the effect of the small hydraulic diameter on the two-phase multiplier.
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  • Wei LIU, Masatoshi KURETA, Hajime AKIMOTO
    2004 Volume 47 Issue 2 Pages 299-305
    Published: 2004
    Released: January 25, 2005
    JOURNALS FREE ACCESS
    The Reduced-Moderation Water Reactor (RMWR) has recently becomes of great concern. The RMWR is expected to promote the effective utilization of uranium recourse. The RMWR is based on water-cooled reactor technology, with achieved under lower core water volume and water flow rate. In comparison with the current light water reactors whose water-to-fuel volume ratio is about 2-3, in the RMWR, this value is reduced to less than 0.5. Thereby, there is a need to research its cooling characteristics. Experimental research on critical power in tight lattice bundle that simulates the RMWR has been carried out in Japan Atomic Energy Research Institute (JAERI). The bundle consists one center rod and six peripheral rods. The 7 rods are arranged on a 14.3mm equilateral triangular pitch. Each rod is 13mm in outside diameter. An axial 12-step power distribution is employed to simulate the complicate heating condition in RMWR. Experiments are carried out under G=100-1400kg/m2s, Pex=2-8.5MPa. Effects of mass velocity, inlet temperature, pressure, radial peaking factor and axial peaking factor on critical power and critical quality are discussed. Compared with axial uniform heating condition, the axial non-uniform heating condition causes an obvious decrease in critical quality. Arai correlation, which is the only correlation that has been optimized for tight lattice condition, is verified with the present experimental data. The correlation is found to be able to give reasonable prediction only around RMWR nominal operating condition.
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  • Koichi HATA, Hirokazu KOMORI, Masahiro SHIOTSU, Nobuaki NODA
    2004 Volume 47 Issue 2 Pages 306-315
    Published: 2004
    Released: January 25, 2005
    JOURNALS FREE ACCESS
    The critical heat fluxes (CHFs) of subcooled water flow boiling for the test tube inner diameters (d=3 and 6mm) and the heated lengths (L=67, 120 and 150mm) are systematically measured for the flow velocities (u=4.0 to 13.3m/s), the inlet subcoolings (ΔTsub, in=48 to 148K), the outlet subcoolings (ΔTsub, out=10.5 to 95.1K), the inlet pressure (Pin=753 to 995kPa) and the outlet pressure (Pout=720 to 887kPa). The SUS304 tubes of L=67, 120 and 150mm for d=3mm and L=150mm for d=6mm are used. The values of L/d are 22, 40 and 50 for d=3mm, and 25 for d=6mm, respectively. The CHFs, qcr, sub, for a fixed ΔTsub, out become gradually lower with an increase in the L/d in the whole experimental range. The CHF correlation against outlet subcooling, which has been previously derived for L/d lower than 16, was modified to new one containing the L/d effect based on these experimental data. Furthermore, the relation between qcr, sub and L/d for a fixed ΔTsub, in was checked. The values of qcr, sub for a fixed ΔTsub, in became exponentially lower with the increase in L/d. CHF correlation against inlet subcooling has been given based on the experimental data for L/d ranging from 4.08 to 50. The correlations against outlet and inlet subcoolings can describe not only the CHFs obtained in this work for the inner diameter of 3 and 6mm at the outlet pressure of around 800kPa but also the authors' published CHFs data (1611 points) for the wide ranges of Pin=159kPa to 1MPa, d=3 to 12mm, L=33 to 150mm and u=4.0 to 13.3m/s within 15% difference for 30K≤ΔTsub, out≤140K and 40K≤ΔTsub, in≤151K.
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  • Hitomi ITOH, Mayumi OCHI, Isao FUJIWARA, Takashi MOMOO
    2004 Volume 47 Issue 2 Pages 316-322
    Published: 2004
    Released: January 25, 2005
    JOURNALS FREE ACCESS
    Life estimation was performed for the stress corrosion cracking (SCC) that occurs in deaerated and wet hot pure steam at the bottoms of the threads of bolts made of SCM435 (equivalent to AISI 4137) used in steam turbine. SCC is believed to occur when corrosion pits are formed and grow to critical size, after which SCC is initiated and cracks propagate until the critical fracture toughness value is reached. Calculations were performed using laboratory and field data. The results showed that, for a 40mm diameter bolt with 0.2% offset strength of 820MPa, the critical crack depth for straight-front cracks was 5.4mm. The SCC life depends on the lubricant used; the SCC life estimated from this value is approximately 70000 hours when graphite is used as a lubricant.
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  • Kazuyuki TAKASE, Hiroyuki YOSHIDA, Yasuo OSE, Hidesada TAMAI
    2004 Volume 47 Issue 2 Pages 323-331
    Published: 2004
    Released: January 25, 2005
    JOURNALS FREE ACCESS
    A reduced-moderation light water reactor (RMWR), which is studied by the Japan Atomic Energy Research Institute, needs to the volume ratio between the coolant and fuel less than 0.2, in order to achieve 1.1 or more high breeding ratios. The RMWR fuel assembly consists of many fuel rods with a diameter of around 10mm with the triangular tight-lattice configuration in the radial direction. A minimum gap width between adjacent fuel rods is about 1mm. Moreover, spacers are set to keep uniformly the gap width between fuel rods horizontally. These spacers are installed at a fixed interval to the flow direction in a reactor core. As a result of this, a complicated flow is formed around each spacer because of a large flow disturbance. Then, fundamental liquid film flow behavior in a narrow channel with a three-dimensional rectangular rib was analyzed numerically using a newly developed two-phase flow analysis code. From this study the following conclusions were derived: a wake behind the spacer rib takes place easier when the initial film thickness is short and then the gas velocity is higher than the liquid velocity; and, the liquid film thickness reduces with increasing the gas velocity.
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  • Kenji KIKUCHI, Shigeru SAITO, Yuji KURATA, Masatoshi FUTAKAWA, Toshino ...
    2004 Volume 47 Issue 2 Pages 332-339
    Published: 2004
    Released: January 25, 2005
    JOURNALS FREE ACCESS
    Lead bismuth eutectic (LBE) is favored by spallation neutron sources and coolant in the sub-critical reactor at the accelerator driven nuclear transmutation system (ADS). Technical issues of ADS are material technology of how to compromise with flowing lead bismuth, high-energy proton accelerator technology and a sub-critical reactor system technology. This paper describes LBE technology developed at JAERI. First a scenario in order to realize the ADS is shown. The concept of spallation target test facility is introduced with a target design of thermo-fluid dynamics. Base data of flow rate and temperature of Pb-Bi during LBE circulation are described. The results of LBE loop operation under the flowing conditions of target design concept are reported. The stagnant corrosion tests were done to know the controlling parameters among the various steels. The tube-type oxygen sensor with having the solid electrolyte was studied. Cleaning techniques were developed to remove LBE from materials.
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  • Kimichika FUKUSHIMA, Takashi OGAWA
    2004 Volume 47 Issue 2 Pages 340-343
    Published: 2004
    Released: January 25, 2005
    JOURNALS FREE ACCESS
    Hydrogen, a potential alternative energy source, is produced commercially by methane (or LPG) steam reforming, a process that requires high temperatures, which are produced by burning fossil fuels. However, as this process generates large amounts of CO2, replacement of the combustion heat source with a nuclear heat source for 773-1173K processes has been proposed in order to eliminate these CO2 emissions. In this paper, a novel method of nuclear hydrogen production by reforming dimethyl ether (DME) with steam at about 573K is proposed. From a thermodynamic equilibrium analysis of DME steam reforming, the authors identified conditions that provide high hydrogen production fraction at low pressure and temperatures of about 523-573K. By setting this low-temperature hydrogen production process upstream from a turbine and nuclear reactor at about 573K, the total energy utilization efficiency according to equilibrium mass and heat balance analysis is about 50%, and it is 75%for a fast breeder reactor (FBR), where turbine is upstream of the reformer.
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  • Yasushi YAMAMOTO, Kouji HIRAIWA, Shinichi MOROOKA, Nobuaki ABE
    2004 Volume 47 Issue 2 Pages 344-350
    Published: 2004
    Released: January 25, 2005
    JOURNALS FREE ACCESS
    An innovative fuel cycle system concept named BARS (BWR with an Advanced Recycle System) has been proposed as a future fuel cycle option aiming at enhanced utilization of uranium resources and reduction of radioactive wastes. In BARS, the spent fuel from conventional light water reactors (LWRs) is recycled as a mixed oxide (MOX) fuel for a BWR core with the fast neutron spectrum by means of oxide dry-processing and vibro-packing fuel fabrication. The fast neutron spectrum is obtained by means of triangular tight fuel lattice. Further study on BARS, especially on tight lattice MOX fuel, has been initiated as a joint study by Toshiba and Gifu University. The objective of this paper is to show the latest progress of the study on BARS, especially concerning the thermal-hydraulics measurements for tight lattice bundle.
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  • Hiroyasu OHTAKE, Yasuo KOIZUMI
    2004 Volume 47 Issue 2 Pages 351-357
    Published: 2004
    Released: January 25, 2005
    JOURNALS FREE ACCESS
    Critical heat fluxes (CHFs) on inclined plates and hemispheres in the case of saturated pool boiling were investigated analytically. In the present model, the most dangerous wavelength and propagation velocity in the Kelvin-Helmholtz instability on the liquid-vapor interface were calculated to determine the length and the velocity of the coalesced bubbles at CHF. The time period for which the coalesced bubble covered the heated surface was calculated as the length divided by the velocity. In close to the surface oriented downward, the characteristic length was provided by the length of the heater; the characteristic velocity was given by the correlation of the rising velocity of a spherical cap bubble with 17 to 40mm the equivalent diameter. The predictions agreed well with previous experimental data obtained for an inclined plate in overall inclination angle. The model given as a function of the inclination angle was developed for the CHF on a hemisphere. The extended model well represented the experimental data on hemispheres.
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  • Noriyoshi MAEDA, Kenichi TAJIMA
    2004 Volume 47 Issue 2 Pages 358-362
    Published: 2004
    Released: January 25, 2005
    JOURNALS FREE ACCESS
    In order to perform research activity for aging countermeasure of nuclear power plant effectively, Plant Life Engineering Center (PLEC) was established in Japan Power Engineering and Inspection Corporation (JAPEIC) in April 2000 sponsored by Ministry of International Trade and Industry (MITI, presently METI). Outlined activities of PLEC are as follows. Results of technical survey for research and development for aging phenomena have been summarized in a table (Research Map) categorizing them into “inspection and monitoring”, “evaluation method for aging” and “preventive maintenances and refurbishment”. Necessary research themes have been extracted from the Research Map consulting to experts of the specified research area and they are summarized into Medium and Long-term Research Perspective (Research Perspective), which contains prioritized research themes and outlined specification of each theme. Several new research themes proposed by various organizations and selected by PLEC as effective for the regulation activities are identified and proposed to be funded by METI every year. This paper also provides outlines and obtained results of aging related research projects currently conducted by JAPEIC sponsored by METI.
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PAPERS
  • Shuzo HIRAHARA, Norio YOSHIKAWA, Hideki NUKADA, Haruhi OH-OKA, Masahir ...
    2004 Volume 47 Issue 2 Pages 363-368
    Published: 2004
    Released: January 25, 2005
    JOURNALS FREE ACCESS
    A noncontact squeegeeing device is used just after the development process in a liquid toner electrophotographic printing system. By using capillary forces, this device removes almost all of the surplus liquid adhering to the photoreceptor surface. Though the device has a simple structure and has even been used in actual systems, there is not much information regarding the mechanism of the device available in the literature, and the mechanism does not seem to have been theoretically analyzed. In this paper, some equations are derived from the lubrication approximation theory based on the condition that total liquid flow is zero. The calculation results obtained using these equations show good agreement with the experimental results for the variation of the characteristics of the squeegeeing efficiency with the circumferential surface velocities of rollers. The proposed equations make the calculation of the squeegeeing characteristics easy and thus facilitate improvement of the device and further development of the system.
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  • Masahiro TAKEI, Mitsuaki OCHI, Yoshifuru SAITO, Kiyoshi HORII
    2004 Volume 47 Issue 2 Pages 369-377
    Published: 2004
    Released: January 25, 2005
    JOURNALS FREE ACCESS
    A new reconstruction method, which is called Generalized Vector Sampled Pattern Matching (GVSPM) method, has been applied to an ill-posed inverse problem of a capacitance-computed tomography for solid air two-phase flow. In pseudo two-phase flow images, the correlation of the reconstructed images by GVSPM is higher than those by a conventional Newton Raphson (NR) iterative method by 32.5%. Moreover, in solid air two-phase flow images, the deviation between the particles volume fraction by experimental capacitance and that by the reconstruction methods is calculated. As a result, the volume fraction deviation of GVSPM reconstructed image is lower than that of NR by 56.7%. Also, the time-mean correlation between the experimental capacitance and the capacitances from the reconstruction method is calculated. As a result, GVSPM method improves the correlation by 23.6%as compared with NR method. The accurate reconstruction of GVSPM results from an inner product calculation between the experimental capacitance and the capacitance from the reconstructed images as an objective function.
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  • Wim BIERBOOMS
    2004 Volume 47 Issue 2 Pages 378-386
    Published: 2004
    Released: January 25, 2005
    JOURNALS FREE ACCESS
    A new method, so called constrained stochastic simulation, has been developed in order to generate extreme gust time series, to be used to calculate the extreme loading of wind turbines. A constrained simulation corresponds to the addition, in a special manner, of turbulence and a deterministic part (which resembles the auto correlation function of turbulence). The stochastic gusts produced in this way has been denoted NewGust and it is proved that they are, in a statistical sense, not distinguishable from gusts selected from a (very long) stochastic time series, with the same amplitude. The NewGust method forms a part of on overall probabilistic method to determine the distribution of the wind turbine response on gusts. This new probabilistic method enables wind turbine manufacturers to build more reliable and optimised wind turbines. The theoretical mean gust shape, as well as the probability of occurrence of gusts, has been verified by measurements. In addition preliminary comparisons between numerical load simulations and wind turbine load measurements have been carried out.
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  • Anugerah WIDIYANTO, Seizo KATO, Naoki MARUYAMA
    2004 Volume 47 Issue 2 Pages 387-395
    Published: 2004
    Released: January 25, 2005
    JOURNALS FREE ACCESS
    For solving decision problems in electric generation planning, a matrix operation based deterministic quantitative model called the Distance Based Approach (DBA) has been proposed for comparing the technical-economical and environmental features of various electric power plants. The customized computer code is developed to evaluate the overall function of alternative energy systems from the performance pattern corresponding to the selected energy attributes. For the purpose of exploring the applicability and the effectiveness of the proposed model, the model is applied to decision problems concerning the selection of energy sources for power generation in Japan. The set of nine energy alternatives includes conventional and new energy technologies of oil fired-, natural gas fired-, coal fired-, nuclear power, hydropower, geothermal, solar photovoltaic, wind power and solar thermal plants. Also, a set of criteria for optimized selection includes five areas of concern; energy economy, energy security, environmental protection, socio-economic development and technological aspects for electric power generation. The result will be a ranking of alternative sources of energy based on the Euclidean composite distance of each alternative to the designated optimal source of energy.
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  • Baoqing DENG, Chang Nyung KIM
    2004 Volume 47 Issue 2 Pages 396-402
    Published: 2004
    Released: January 25, 2005
    JOURNALS FREE ACCESS
    This paper presents a new CFD model for the transportation of volatile organic compound (VOC) from building materials to the room air in the case with high VOC concentration in the air when Langmuir model or other nonlinear adsorption isotherms are used. In this model, the concentration equation solves the equivalent air-phase concentration and uses the equivalent air-phase diffusion coefficient to calculate the mass flux. A new parameter, specific mass, arising from adsorption isotherm is presented to account for the sorption and desorption effect. The present model and two previous models are applied to the steady and unsteady problems. Results show that the present model correctly simulates the emission of VOC from building materials. And the present model is easy to use with commercial CFD software.
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  • Kazuhiro YAMAMOTO, Xiaoyi HE, Gary D. DOOLEN
    2004 Volume 47 Issue 2 Pages 403-409
    Published: 2004
    Released: January 25, 2005
    JOURNALS FREE ACCESS
    Even though laser diagnostics have significantly improved and can obtain an instantaneous 2D flame image of the velocity field, it is still difficult to obtain data such as scalar flux or reaction rates experimentally. It is also essential to understand 3D flame structures in turbulent combustion. Chemically non-reacting turbulent flows are complex and chemical reactions make the problem more complicated. Due to practical limitations of computational costs, conventional numerical methods are very expensive for carrying out 3D numerical simulations at high Reynolds numbers with detailed chemical reactions. In this study, we have used the lattice Boltzmann method (LBM) to simulate a combustion field. The LBM is an efficient alternative for the numerical simulation of this type of flow. To confirm the validity of the LBM, a flame in simple flow geometry is simulated and the laminar burning velocity is obtained. Both 2D and 3D simulations have been completed. A jet flame has been also simulated to demonstrate the LBM capability of simulating unsteady flames with vortices. The scheme with detailed chemistry has been tested for simulation of a counter-flow flame.
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  • Yonggyu LEE, Changup KIM, Seungmook OH, Kernyong KANG
    2004 Volume 47 Issue 2 Pages 410-415
    Published: 2004
    Released: January 25, 2005
    JOURNALS FREE ACCESS
    Effects of injection timing on mixture distribution were investigated in a liquid phase LPG injection engine for a heavy-duty vehicle. An optically accessible engine was made for planar laser induced fluorescence and flame imaging. Mixture distributions around the spark plug were quantified and compared for open and closed valve injection. Two-dimensional flame images were taken to investigate the effect of mixture stratification on flame propagation. In addition, the overall engine performance and emissions were compared for the injection timings at a selected condition. Unlike the case of closed valve injection, where a nearly homogeneous mixture is formed near the spark plug and the flame moves with swirl, in the case of open valve injection, a cloud of richer mixture than overall excess air ratio is formed near the spark plug and the flame moves in the direction of the rich mixture, which extends the limit of lean burn operation.
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