KAGAKU KOGAKU RONBUNSHU
Online ISSN : 1349-9203
Print ISSN : 0386-216X
ISSN-L : 0386-216X
Volume 26 , Issue 1
Showing 1-23 articles out of 23 articles from the selected issue
  • TSUTOMU OHISHI, SETSURO HIRAOKA, YOSHIHITO KATO, YUTAKA TADA, NAOAKI I ...
    2000 Volume 26 Issue 1 Pages 1-5
    Published: January 10, 2000
    Released: July 27, 2010
    JOURNALS FREE ACCESS
    Power consumption in an agitated vessel with an “EGSTAR” agitator, which has been practically used as a bioreactor, was measured under aeration. The power consumption of the “EGSTAR” agitator did not decrease so much with aeration, in contrast to the result of a disk turbine impeller. In the turbulent flow region of Red>300, the power number at a specified gas flow rate takes a maximum value. The correlations of the maximum power number Npg, R and the rotational speed NR at which the power number takes the maximum are derived using both operating conditions and impeller dimensions.
    The power number under aeration Npg in the range of N/NR>1 in turbulent flow region is correlated with the rotational speed N, with help of NR and Npg, R, as
    Np/Npg, R= (N/NR) -0.30
    The combination of the correlation of Npg above with the correlations of Npg, R and NR gives rise to the following power correlation of EGSTAR agitator under aeration.
    Npg=0.68NA-0.08
    Fr-0.19
    (hd/d) 0.01
    (1-ε) 0.22
    Np, R
    The power consumption of EGSTAR agitator under aeration is not affected so much by gas flow rate, in contrast to the result of a disk turbine impeller.
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  • TOMIO MIMURA, KOUJI MATUMOTO, MASAKI IIJIMA, SHIGEAKI MITSUOKA
    2000 Volume 26 Issue 1 Pages 6-10
    Published: January 10, 2000
    Released: July 27, 2010
    JOURNALS FREE ACCESS
    Applicability of the chemical absorption process to carbon dioxide removal and recovery under effluent gas conditions equivalent to those for coal-fired power plants was tested.
    From the pilot plant test results using KS-3 absorbent at an exhaust gas flow rate of 450m3/h, overall performance of the system was confirmed by about 200 hours' operation with 50ppm coexisting SOx.
    Furthermore it is found, that longer operation is permitted, judging from the experimental evidence of KS-3's corrosion properties under coal-fired conditions compared to those at LNG-fired power plants.
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  • KENJI YASUNAKA, TSUKASA FUJIMURA, NOBUYUKI NISIMOTO
    2000 Volume 26 Issue 1 Pages 11-17
    Published: January 10, 2000
    Released: March 15, 2010
    JOURNALS FREE ACCESS
    The purpose of this report is to elucidate influence of welding conditions on seam weldability of a surface-finished steel sheet. The analytical equation for temperature rising in welding was obtained by means of Joule's heating law for the proposal welding model. Then, the relation between the weldability and the welding condition was considered.
    The experimental results are as follows.
    (1) Weldability becomes poor with an increase in welding speed. (2) Weldability improves with increasing current frequency. (3) Weldability improves with an increase in applied force.
    From the analytical equation, temperature at the end of the current path (exit point of electrode) changes periodically with current frequency and these deviations increase with increasing speed, decreasing current frequency and decreasing current path. It is considered that “Splash” is easy to cause, as much as the wider temperature deviation, and then weldability becomes poor. These analytical results may support the experimental results qualitatively.
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  • KOZO ARAHORI, TOSHIHARU SHIBATA, KUNIO SHINOHARA, TOMOYUKI UCHIYAMA, M ...
    2000 Volume 26 Issue 1 Pages 18-22
    Published: January 10, 2000
    Released: March 15, 2010
    JOURNALS FREE ACCESS
    Lapping tests are carried out with an artificial poly-crystal diamond powder of sharp size-distribution and different shapes. The effect of particle shape on lapping characteristics is examined. The particle shape is described by expanding x and y coordinates of the particle outline into Fourier seriesindependently. Then, the shape is represented by elongation ratio of the approximated ellipse calculated from the first-order Fourier coefficient and asymmetricity, polygonality and edge sharpness by slopes along the particle outline based on higher-order Fourier coefficients. Lapping characteristics are evaluated by the rate of decrease in work thickness, and by the surface roughness. As a result, a correlation equation was obtained where the lapping rate increases with increasing polygonality and edge sharpness and decreasing elongation and asymmetricity, and the surface roughness isn't significantly affected by the particle shape. Thus, it becomes possible to prepare diamond particles of different shapes by adjusting only the lapping rate.
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  • ATSUKO SHIMOSAKA, KOJI HAYASHI, YOSHIYUKI SHIRAKAWA, JUSUKE HIDAKA
    2000 Volume 26 Issue 1 Pages 23-30
    Published: January 10, 2000
    Released: March 15, 2010
    JOURNALS FREE ACCESS
    Stress analysis in the compaction of ceramic powder was performed by Finite Element Method (FEM) to predict the optimum conditions. In order to apply to practical problem, the powder bed was treated as elasto-plastic material, and the constitutive equation was derived from Drucker-prager's yield function expressed in terms of invariants of stress tensors and Hill's anisotropic parameters on stress in the powder bed. The powder bed has multiform bulk density distribution, along with behavior of discontinuous deformation during compression whereby, the mechanical characteristics of the powder bed change during compaction. Thus, it is necessary that the powder characteristics are treated as a variant associate with the progress of powder compaction.
    In this paper, Young's modulus and strain-hardening rate are expressed as a function of minor principal stress and strain. These function can be determined from a triaxial compression test. Hill's anisotropy parameters induced at compaction process were numerically obtained by simulation of the compacting behavior of particles which was performed by Particle Element Method (PEM).
    On the basis of the proposed constitutive model, the problem of powder compaction is analyzed. The calculated results of the nonlinear stress-strain relation, stress distribution during powder compaction agree well with the measured ones. It is shown that the procedure proposed here offer the useful information to decide the optimun conditions of powder compaction.
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  • YOSHIRO INOUE, YUSHI HIRATA
    2000 Volume 26 Issue 1 Pages 31-39
    Published: January 10, 2000
    Released: March 15, 2010
    JOURNALS FREE ACCESS
    In order to clarify the fundamental relation between fluid mixing and flow field, mixing processes in a time-periodic cellular convection are numerically analyzed. The effects of amplitude and frequency of the perturbation flow on mixing rate, mixedness and final mixing pattern are quantitatively analyzed with new measures of mixedness. The increase in amplitude of perturbation enhances both the mixing rate and the mixedness, but brings about no quantitative change in the mixing pattern. On the other hand, change in the frequency reconstructs the fundamental structure of the mixing pattern and causes serious and complex changes in the mixing rate and the final mixedness, because the frequency relates to the resonance condition of the flow field.
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  • SUSUMU TAKAHASHI, KORYO KOJIMA, MASANARI KUDO, SANKICHI TAKAHASHI
    2000 Volume 26 Issue 1 Pages 40-44
    Published: January 10, 2000
    Released: March 15, 2010
    JOURNALS FREE ACCESS
    The changes in the liquid structure and the state of hydrogen bonds of water with respect to temperature change were examined experimentally using the 17O-chemical shift method. Three types of water of identical origin having different concentrations of dissolved salts were used as samples. The following results were obtained:
    1) The 17O-chemical shift method is useful for analyzing the liquid structure of the water because 17O-chemical shift is not effected by the concentration of dissolved salt and thus a continuous spectrum can be obtained.
    2) Using a logarithmic temperature scale, the transition temperatures of the liquid structure of water are confirmed to be at 288K and 313K, which is consistent with values indicated by temperature dependency of density and specific heat of the water.
    3) The temperature dependency of 17O-chemical shift can be explained using continuum and mixture models.
    4) The correlation between 17O-chemical shift and half-width can be evaluated by displaying their temperature dependency along with the ratio of [H+] at 313K and that at a given temperature.
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  • OSAMU TANOUE, MITSUHIRO YOSHIDA, YOICHIRO KOGA, RYUICHI UEOKA
    2000 Volume 26 Issue 1 Pages 45-49
    Published: January 10, 2000
    Released: March 15, 2010
    JOURNALS FREE ACCESS
    In order to develop a new reaction-control system with artificial enzymes, we investigated the hydrolytic cleavage of p-nitrophenyl esters (CnPNP) catalyzed by hydroxamic acids (HA) in cationic micellar (CTAB) and reversed micellar (CTAB) aggregate systems in aqueous solutions and organic media, respectively. It is noted that the remarkably highly rate-enhancement for the long-chained substrate (p-nitrophenyl hexanoate, C6PNP) with the long-chained catalyst (2-hexyldecanohydroxamic acid, HDHA) in the CATB micellar systems should be fairly related to a favorable orientation of reactants through the hydrophobic interaction between C6PNP and comicelles of CTAB and HDHA. On the other hand, it is found that the short-chained substrate (p-nitrophenyl acetate, C2PNP) is most effective for its hydrolytic cleavage with the hydrophilic catalyst (benzohydroxamic acid, BHA) in the CTAB reversed micellar system. This might be attributable to a higher distribution ratio of the C2PNP into the inner aqueous phase than those of longer-chained substrates.
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  • KOICHIRO SHIOMORI, YOSHINOBU KAWANO, SHIRO KIYOYAMA, HIDEKAZU YOSHIZAW ...
    2000 Volume 26 Issue 1 Pages 50-55
    Published: January 10, 2000
    Released: March 15, 2010
    JOURNALS FREE ACCESS
    Entrapment of bovine serum albumin into microcapsule using polylactic acid as a wall material was carried out by solvent evaporation of a W/O/W emulsion prepared by a two-step emulsification method. Effects of the conditions in the first step emulsification, which gave a W/O emulsion, and the concentrations of additives in the inner and outer aqueous phases on the entrapment efficiency and the morphology of the microcapsule are discussed. The entrapment efficiency of albumin decreases with increasing in the hold up of dispersion phase in the first step W/O emulsion preparation, and the concentration of additives in the inner aqueous phase. On the other hand, by ultrasonic treatment for W/O emulsion and an increase in the concentration of additives in the outer aqueous phase, entrapment efficiency of the protein increases. Permeation of water from the outer into the inner aqueous phase by osmotic pressure difference, which causes the coalescence of the inner aqueous phase droplets and a decrease in the capsule wall thickness, decreases the entrapment efficiency. By considering these factors, almost all the amount of albumin dissolved in the inner aqueous phase can be entrapped in the capsule, and it is possible to control the entrapment of water soluble core materials in the preparation of microcapsules by the solvent evaporation method.
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  • KOSAKU ISHIMI, YUICHI KOYAMA, NAOYUKI OKAZAKI, HARUO ISHIKAWA
    2000 Volume 26 Issue 1 Pages 56-61
    Published: January 10, 2000
    Released: March 15, 2010
    JOURNALS FREE ACCESS
    Flow of a Newtonian liquid film and the supporting liquid with a longitudinal wave disturbance, which is imparted to the liquid film by means of a sinusoidally oscillating barrier, is numerically simulated in a rectangular trough. The effects of surface dilatational viscosity and elasticity of the liquid film on amplitudes and time lags of tracer particles deposited on the liquid film are investigated. A comparison between the present theoretical results and predictions based on a linear oscillation theory by Maru and Wasan (1979b) indicates that the oscillation of films cannot be expressed by the simple linear theory, and that the measurement of surface dilatational viscosity by the longitudinal wave technique needs a more exact analytical method. Experiments on the oscillation in a castor oil-water system were carried out. Analysis of the experimental results based on the present theory shows that the surface dilatational viscosity of castor oil is Newtonian.
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  • MAKIO NAITO, TADASHI HOTTA, TOMOHIDE TANIMOTO, SHIGEHISA ENDOH, KIYOSH ...
    2000 Volume 26 Issue 1 Pages 62-67
    Published: January 10, 2000
    Released: March 15, 2010
    JOURNALS FREE ACCESS
    The composite process of deposition of fine particles onto the surface of core particles by a highspeed elliptical-rotor-type mixer is analyzed. In this paper, the effect of fine particle size on the composite process is investigated. Soda-lime glass beads were selected as core particles, and three kinds of titanium dioxide were used as fine particles. The mass fraction of fine particles fixed on the surface of the core particles was measured with a wet sieve technique, and the coated layer of fine particles was observed by a scanning electron microscope.
    As a result, the mass fraction of fine particles deposited onto the surface of the core particle increases as the rotor revolution and the processing time increase regardless of fine particle size. However, the detachment of fine particles from the core particles occurs after a certain processing time regardless of fine particle size. The critical revolution decreases as the fine particle size increases. Below the critical revolution, the mass fraction of fine particles increases as the fine particle size decreases. These results are explained by considering the cechanics of powder beds.
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  • ROBERTO MASSAHIRO SERIKAWA, TAKASHI USUI, TATSUYA NISHIMURA, HIROKAZU ...
    2000 Volume 26 Issue 1 Pages 68-75
    Published: January 10, 2000
    Released: March 15, 2010
    JOURNALS FREE ACCESS
    SCWO characteristics are investigated for a vertical type, down stream continuous reactor system with mixing nozzle and sapphire windows. 2-propanol, hexane and biphenyl solution are used as fuel and air as oxidizer. 2-propanol is observed to be effective as makeup fuel to keep a stable autogenic SCWO reaction. Even for low air ratio as 1.1, high decomposition rate without CO, NO, NO2 or soot production is achieved. Calculated and experimental flue gas composition is in good agreement for a wide range of air ratio. Spontaneous flame formation is observed for SCWO of 2-propanol using air ratio over 1.8. These flame formations are not particular to 2-propanol and are also confirmed when using hexane and biphenyl solution as fuel.
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  • HIDEO SHINAGAWA, KIKUO OKUYAMA
    2000 Volume 26 Issue 1 Pages 76-80
    Published: January 10, 2000
    Released: March 15, 2010
    JOURNALS FREE ACCESS
    The distribution of molecular number flux reflecting from the conduit wall along the conduit axis in the free molecular flow through a cylindrical tube with an orifice restricted exit was analyzed based on an analogy between free molecular flow and radiative heat transfer, and a Monte Carlo method. The distribution of the molecular number density on the conduit wall along the conduit axis was determined by assuming that the ratio of the molecular number flux reflecting from the conduit wall to that entering into the conduit inlet corresponds to the ratio of the molecular number densities at each position. The distribution of molecular number density determined by both analyses were in good agreement. The molecular number density increases with increasing cross-sectional area ratio of cylindrical tube to orifice opening β. The distribution of molecular number density in the conduit with length to radius ratio L/R 1 and β 2 has a minimum, and the position at which the minimum occurs shifts to the downstream side with increasing L/R.
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  • SHIRO KIYOYAMA, KOICHIRO SHIOMORI, YOSHINOBU KAWANO, KEISUKE FUKADA, Y ...
    2000 Volume 26 Issue 1 Pages 81-87
    Published: January 10, 2000
    Released: March 15, 2010
    JOURNALS FREE ACCESS
    Abstract A continuous emulsification apparatus, which was a column type mixer with vibration plates, is developed. The characteristics of emulsification using the emulsifier are investigated under various experimental conditions. The mean residence time and volume fraction of dispersion phase have almost no effect on average diameter and variance of the emulsion prepared. It is found that the average diameter and it's variance are determined by the frequency and ratio of space area between the vibration plates and cross-section of the emulsifier (R). The average diameter of the emulsion is formulated as a function of the frequency and the ratio of space area at constant values of mean residence time and volume fraction of dispersion phase as following equations.
    D=a·fb
    aO/W=8.07×109R4.74, bO/W=-1.28log (R) -2.67
    aW/O=6.95×105R+0.55, bW/O=-1.43
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  • AKIRA NISHIMURA, SEIICHI DEGUCHI, HITOKI MATSUDA, MASANOBU HASATANI, A ...
    2000 Volume 26 Issue 1 Pages 88-93
    Published: January 10, 2000
    Released: March 15, 2010
    JOURNALS FREE ACCESS
    A pulsated fluidized bed is operated with two sequential durations of “on-period” with injecting fluidization air and “off-period” without injecting fluidization air. The experiments were carried out under intermittent fluidizing conditions consisting of the static bed formed through the whole bed during an off-period duration and fluidizing bed during an on-period duration. The effects of particle size, fluidization air velocity, and initial bed height on the characteristics of bubbles, which may strongly affect the particle mixing behaviors and heat transfer efficiency, are investigated. The number of bubbles and bubble size during the cycle were evaluated with a digital video camera. As a result, it can be seen that the fluidization air injected to the static bed induces either normal bubbling fluidization or large bubble fluidization with lifting up the static bed. It is recognized that the fluidizing state is shifted from normal bubbling fluidization to large bubble fluidization with increasing air veloity and/or initial bed height. It is found that large bubble fluidization, which is a characteristic of the pulsated fluidized bed, can be formed under lower air velocity with smaller particle.
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  • MANABU KANO, Natthaphon Showchaiya, SHINJI HASEBE, IORI HASHIMOTO
    2000 Volume 26 Issue 1 Pages 94-99
    Published: January 10, 2000
    Released: March 15, 2010
    JOURNALS FREE ACCESS
    For controlling product quality, which is difficult to measure on-line, an effective approach is to build an inferential control system. In the inferential control system, quality variables are estimated from measured process variables, and the estimates are controlled. Since the performance of the inferential control system depends on the inferential model, appropriate selection of the model is crucial for effective performance of the inferential control system. In this article, the performance of inferential control systems using steady-state, static, and dynamic models are compared. From the viewpoint of estimation, dynamic models are much better than both steady-state and static models. Nevertheless, the best control performance cannot be achieved by using the dynamic model. In addition, it is shown that manipulated variables must not be used as input variables of the inferential model.
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  • NORIKAZU NAMIKI, YOSHIO OTANI, CHI-MUN YUN, HITOSHI EMI, TAKESHI YAMAD ...
    2000 Volume 26 Issue 1 Pages 100-104
    Published: January 10, 2000
    Released: March 15, 2010
    JOURNALS FREE ACCESS
    Silica particles generated with Raskin nozzles are suggested as a substitute for DOP (dioctyl phthalate) particles for testing HEPA filters. However, the generation characteristics of Raskin nozzles from the silica suspension are not well understood yet. The present work investigates the generation characteristics of Raskin nozzles for silica particles by measuring the size distribution, the mass or number concentrations of silica particles and their electrical charges. As a result, (i) although atomization pressure increases mass or number concentration, the size distributions remain rather unchanged, (ii) suspension of smaller primary silica particles generates smaller agglomerated particles with a higher mass concentration, and (iii) a higher concentration of suspension does not necessarily generate a higher concentration of particles. Further, the light scattering characteristics of silica particles by LPC were evaluated by classifying the silica particles according to the electrical mobility. The LPC underestimates the size of silica particles by a factor of about 1.6 compared to DOP particles, leading to a serious deviation in particle penetration through air filters. Special caution is required for the light scattering characteristics and electrical charge when silica particles are used as a substitute of DOP particles for filter test.
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  • HIRONOBU IMAKOMA, TAKUJI YANO, KATSUYUKI KUBOTA, NAOTO OHOMURA, KUNIO ...
    2000 Volume 26 Issue 1 Pages 105-107
    Published: January 10, 2000
    Released: March 15, 2010
    JOURNALS FREE ACCESS
    Machine-made paper is a typical orthogonal anisotropic material vis-a-vis conductive heat transfer, and the effective thermal conductivity may change with moisture content. Two-dimensional temperature change with time within a layer of recycled paper sheets was measured using by an unsteady heating method with fine hot wire. Repeated the measurement, three-dimensional effective thermal conductivity of the layer was obtained from a set of analytical solution for the conductive heat transfer equation of the anisotropic media. The measured conductivity increases with moisture content on each dimension, and stepwisely near the fiber saturation point, which is estimated through the adsorption isotherm measured in the study.
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  • RYOICHI NAGATA, SHINICHIRO GONDO, YOSHIMITSU UEMURA, YASUO HATATE
    2000 Volume 26 Issue 1 Pages 108-111
    Published: January 10, 2000
    Released: March 15, 2010
    JOURNALS FREE ACCESS
    MnO2 was immobilized in polyvinyl chloride membrane. A hydrogen peroxide sensor was set up by attaching the immobilized MnO2 membrane on top of a dissolved oxygen sensor of galvanic type. For comparison, sensors using catalase were also set up with immobilized catalase membrane or particles.
    The sensor was dipped in a certain volume of distilled water at a given temperature. Then, hydrogen peroxide aqueous solution of the fixed volume and concentration was added to the distilled water, and the response characteristics and stability of the sensor were investigated.
    The results obtained are summarized as follows. 1) It is found that the MnO2 membrane can be used as a membrane recognizing molecule for a hydrogen peroxide sensor. 2) The steady response value of these sensors is proportional to H2O2 concentration. 3) The response rate of the sensor using immobilized MnO2 membrane is the same as that of the sensor using immobilized catalase membrane. 4) When these sensors are stored in the distilled water at room temperature while not used, the sensor using MnO2 membrane shows stable response for more than three months.
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  • KENSAKU NAKAMURA, TOMOYUKI MIYATA, KAZUO NAKAMURA, KENJI YAMADA, HIROK ...
    2000 Volume 26 Issue 1 Pages 112-115
    Published: January 10, 2000
    Released: March 15, 2010
    JOURNALS FREE ACCESS
    With the aim of studying effective heat-energy exchange solutions in the Kalina cycle, highpressure and high-temperature vapor-liquid equilibrium relations for binary systems containing perfluorobenzene were measured in a pressure range up to 10MPa at 323.15 and 373.15K by use of a newly developed static equilibrium apparatus.
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  • KEIJI YASUDA, YOSHIKAZU TANAKA, HAJIME SUGITA, YOSHIYUKI BANDO, MASAAK ...
    2000 Volume 26 Issue 1 Pages 116-118
    Published: January 10, 2000
    Released: March 15, 2010
    JOURNALS FREE ACCESS
    In order to clarify the behavior of silica deposition in geothermal brine, the effects of initial concentration of silica monomer and pH on the mass of silica deposited on the surface of metal were examined by a Quartz Crystal Microbalance. The mass of deposited silica increases with increasing initial concentration of silica monomer. The behavior of silica deposition is different below pH=6 and above pH=7. It is considered that silica polymers with relatively low molecular weight deposited on the surface of metal as well as the silica monomer are deposited, but those with very high molecular weight are hardly deposited.
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  • JUN FUKAI, AKIRA OISHI, HIROMI OMORI, MAKOTO KANOU, YOSHIKAZU KODAMA, ...
    2000 Volume 26 Issue 1 Pages 119-121
    Published: January 10, 2000
    Released: March 15, 2010
    JOURNALS FREE ACCESS
    Carbon fibers with a high thermal conductivity were used to enhance the thermal conductivity of paraffin. Discharge characteristics of a capsule-type thermal energy storage unit using the carbon-fiber/ paraffin composite was experimentally examined. The volume fraction of the carbon fibers was changed from zero to 2%, The experimental results demonstrate that carbon fibers essentially improve the discharge characteristics of the heat storage unit. A heat transfer model previously developed by one of the authors almost predicts the experimental results.
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  • TAKAHIRO KAWAKATSU, NAOYA ODA, TOSHIKUNI YONEMOTO, MITSUTOSHI NAKAJIMA
    2000 Volume 26 Issue 1 Pages 122-125
    Published: January 10, 2000
    Released: March 15, 2010
    JOURNALS FREE ACCESS
    Monodispersed albumin gel microcapsules were produced by heat treatment of W/O (water in oil) emulsion which is prepared from albumin solution and decane containing tetraglycerin condensed ricinoleic ester as a surfactant using microchannel emulsification. The average size, standard deviation and geometric standard deviation of the gel microcapsules are 20μm, no more than 1μm and no more than 1.05, respectively, which are almost the same as those of W/O emulsion droplets.
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