KAGAKU KOGAKU RONBUNSHU
Online ISSN : 1349-9203
Print ISSN : 0386-216X
ISSN-L : 0386-216X
Volume 34 , Issue 1
Showing 1-31 articles out of 31 articles from the selected issue
Special Issue [Phenomenological Analysis and Process Intensification]
  • Chiaki Kuroda, Hideyuki Matsumoto, Satoko Fujioka
    Type: Reviews
    2008 Volume 34 Issue 1 Pages 1-7
    Published: January 20, 2008
    Released: February 06, 2008
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    This study describes an original view of the expected process intensification (PI) and a methodology for its realization by comparing the present state and trends of PI in the United Kingdom, Europe and USA with those in Japan. It is presently thought that PI should be a model-based process design strategy involving technological innovation at the core of green process engineering (GPE) with the aim of a quantum leap. On the other hand, a clear concept of PI is yet to emerge in Japan, and while it is sometimes interpreted in the above manner, the meaning of model-based is a little different. In particular, constructive design techniques based on phenomenalistic models are regarded as important, through which a quantum leap may be expected to emerge. For the expected PI technology, the systematic integration of process systems, namely compactification, is important, and this will result in complicated systems incorporating many precise elements. This will require a complicated system design strategy that surveys, in order, material design, device design and process design, in which one of the essential problems will be multi-scale modeling- simulation of dynamic complicated systems. In sum, the expected PI will involve design and development strategies for process technology that integrate new model-based unit operations based on various phenomenalistic models represented by the transport phenomena theory. A remaining problem will be further development of precise, efficient and flexible modeling-simulation techniques of complicated systems.
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  • Kazuhiro Mae, Taisuke Maki, Nobuaki Aoki
    Type: Reviews
    2008 Volume 34 Issue 1 Pages 8-17
    Published: January 20, 2008
    Released: February 06, 2008
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    In micro space, mixing and heat transfer are promoted by changing the balance of transport properties. Mixing in micro space is categorized into two types: rapid mixing and precise diffusion control. In this paper, these mixing types were expressed in terms of micro fluid segment. Since rapid mixing is accomplished through proper design of the micro mixer, the logic of micro mixing was summarized with the effect for the production of nano-particles. The possibility of a new reaction system design was also evaluated by the effectiveness for a strict control of active species based on the reaction mechanism. On the other hand, it was shown that precise diffusion control by designing a micro space had a significant effect for strict control of nano-particle size. In addition, the layout of micro fluid segments in the microreactor was also effective for controlling the selectivity of multiple reactions. Based on these results, a method of reactor design including segment shape was proposed as a vector of new reaction engineering for process intensification.
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  • Hideki Tokanai, Eiji Harada, Masafumi Kuriyama
    Type: Research Papers
    2008 Volume 34 Issue 1 Pages 18-24
    Published: January 20, 2008
    Released: February 06, 2008
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    The local heat transfer and air flow characteristics were experimentally investigated in the wake region formed behind a vertical flat plate in uniform air flow. In the wake region, a dead space in which the air flow velocity was extremely small was formed behind the vertical plate. Near the top edge of the dead space, it was found that the air velocity was increased and a large velocity fluctuation was generated. The heat transfer coefficient was small in the dead space because natural convection mainly occurred. Under suitable conditions, however, the heat transfer was enhanced by almost 50% over that in the absence of the vortex promoter.
    From consideration of the heat transfer enhancement, air flow velocity and velocity fluctuation, a correlation equation was proposed for the heat transfer coefficients. Namely, the Nusselt numbers at each position in the wake region were evaluated combination of the Nusselt number for the velocity fluctuation and that in uniform air flow.
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  • Hideki Tokanai, Eiji Harada, Masafumi Kuriyama
    Type: Research Papers
    2008 Volume 34 Issue 1 Pages 25-31
    Published: January 20, 2008
    Released: February 06, 2008
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    An experimental investigation was performed to clarify the heat transfer characteristics of thermal storage particle–water slurry in which micro-capsulated phase-change particles were dispersed in water through a capillary. First, the physical properties including density, thermal conductivity and specific heat of thermal storage particles were evaluated by measuring the physical properties of the slurry. From flow experiments in a capillary, it was confirmed that the thermal storage particle slurries was a power-law fluids, and the apparent viscosity of the slurries was a obtained.
    Next, heat transfer experiments were carried out for the slurry in the capillary. As a result, the heat transfer coefficient under the phase-change condition was found to increase up to twice the value under the non-phase-change condition. By use of appropriate properties to define the non-dimensional parameters, it was found that the heat transfer coefficients of slurry were expressed well by the empirical correlation commonly used.
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  • Shiro Yoshikawa, Tai Shimasaki
    Type: Research Papers
    2008 Volume 34 Issue 1 Pages 32-39
    Published: January 20, 2008
    Released: February 06, 2008
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    Cross-flow ultrafiltration of macromolecule solutions in a module with microchannels is expected to afford faster diffusion from the membrane surface and other advantages. Cross-flow ultrafiltration devices with microchannels are expected to be used for separation and refining and as membrane reactors in microchemical processes. Though these devices can be applied for continuous operation of microchemical processes, there have been few papers on their performance. The purpose of this study is to understand the relationship among operational conditions and performance of cross-flow ultrafiltration devices with microchannels.
    In this study, PVP aqueous solution was used as a model solute of macromolecules such as enzymes. Cross-flow ultrafiltration experiments were carried out under constant pressure conditions at various operational conditions. The permeate flux decreased in the beginning of each experiment. After about 2,000 seconds, the permeate flux reached a constant value. In this study, the performance of the device was discussed based on the constant values. It appeared that the permeate flux increased with increases of transmembrane pressure (TMP) and feed flow rate and that it decreased with increase of feed fluid concentration. These results indicate that the distributions of pressure and concentration in the axial direction of the channel and the axial convective transport of the solute have significant effects on the permeate flux.
    Based on these indications, a new model of the transport phenomena in the feed liquid side channel and the permeation through the membrane was developed. In the model, concentration distributions in the cross sections at the local axial position of the channel were derived taking the concentration polarization model into account. From the relationship between concentration and viscosity of the solution, the velocity distributions in the cross sections were obtained. Based on the distributions and the mass balance, osmotic pressure, transmembrane pressure and permeate flux at a local axial position were calculated. As a result, the permeate flux of the module was calculated as an average value of the distribution of permeate flux in the axial direction of the channel. The calculated results were confirmed to be valid experimentally. This model is expected to be useful in design of cross-flow ultrafiltration modules and the determination of operational conditions.
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  • Masaki Simazoe, Yuusuke Sugikawa, Toshihisa Ueda
    Type: Research Papers
    2008 Volume 34 Issue 1 Pages 40-47
    Published: January 20, 2008
    Released: February 06, 2008
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    The effect of periodic operation on the mixing process of a non-element mixer was investigated experimentally. Into the main flow of glycerin in a pipe of 10 mm ID, more glycerin was injected periodically through a perpendicular branch pipe of 3 mm ID. The flow was intrinsically laminar. When the branch flow was injected, the fluid was folded and stretched under the influence of the parabolic velocity distribution of the pipe flow. The flow pattern was determined by the flow volumes of the main and branch flows in one period. The mixing pattern was modeled as an axi-symmetric interface. The progress of the mixing was estimated by advective mixing and mixing due to molecular mixing. The advective mixing was quantitatively estimated from the increase in the area of the interface between the main flow and the branching flow. The mixing due to molecular mixing was estimated from the concentration distribution in the pipe. In addition, the ratio between the area where advective mixing is dominant and that where mixing due to molecular diffusion is dominant was defined. The progress of the mixing could be estimated from the total value of the advective mixing and the mixing due to molecular diffusion and the area ratio between advective mixing and mixing due to molecular diffusion.
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  • Sakiko Daimon, Buntaro Okada, Yushi Hirata, Yoshiro Inoue
    Type: Research Papers
    2008 Volume 34 Issue 1 Pages 48-56
    Published: January 20, 2008
    Released: February 06, 2008
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    To clarify the influence of mixing on chemical reactions, the effects of convective and diffusive mixing on the spatiotemporal structure of the concentration field in a Lotka-Volterra periodic reaction is analyzed. At the beginning of mixing, concentration distribution is not uniform spatially, and the oscillation mode differs at every position. After a long time, however, the concentration becomes uniform throughout a whole system, and then synchronizes and oscillates with a unique period. The whole concentration field is regarded as an assembly of concentration oscillators. This assembly is a dynamical network of short-range interactions due to diffusion and recombination caused by convective flow. With this model, the process to final coherent oscillation mode and the factors affecting on it were analyzed.
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  • Hideki Hagihara, Yushi Hirata, Yoshiro Inoue
    Type: Research Papers
    2008 Volume 34 Issue 1 Pages 57-63
    Published: January 20, 2008
    Released: February 06, 2008
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    Appropriate patterning of pH distribution to obtain high conversion and selectivity of the main product was analyzed for series-parallel reactions whose reaction rates strongly depend on hydrogen ion concentration, under laminar flow in microchannels. When pH distribution in the inlet solution is adjusted so as to enhance the main reaction and suppress side reactions, the selectivity increases but conversion decreases. However, by increasing the number of inlet channels, it is possible to raise both conversion and selectivity. In addition, the conditions for obtaining high selectivity by collecting only the partial stream containing a high concentration of the main product at the outlet of a microchannel were analyzed.
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  • Keigo Matsuda, Koichi Iwakabe, Masaru Nakaiwa, Hitoshi Kosuge, Sho Kat ...
    Type: Research Papers
    2008 Volume 34 Issue 1 Pages 64-69
    Published: January 20, 2008
    Released: February 06, 2008
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    The present work discusses a method for process intensification of the distillation process of separation. A model of an internally heat-integrated distillation column (HIDiC) with concentric and compact heat exchanger types was developed using a rate-based model and the separation of multicomponent mixture was simulated in a simulator which is capable of predicting steady-state conditions. The developed model was applied to concentric and compact heat exchanger types of HIDiC, and their separation and operation performances were compared. It was found that the HIDiC compact heat exchanger process can also be used for zero reflux and/or no reboil operation. This process improved the function and performance of conventional distillation separation process and could be miniaturized. In addition, the HIDiC compact heat exchanger showed highly energy saving performance compared with the conventional distillation processes.
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  • Kinpei Horiuchi, Masaru Nakaiwa, Koichi Iwakabe, Keigo Matsuda, Masayu ...
    Type: Research Papers
    2008 Volume 34 Issue 1 Pages 70-75
    Published: January 20, 2008
    Released: February 06, 2008
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    Operation and energy savings in the separation of a twelve-component hydrocarbon mixture by the pilot plant of an internally heat-integrated distillation column (HIDiC) were studied. Based on the operation results, a HIDiC simulator was developed using the commercial process-simulation software. The operation and simulation results showed that zero external reflux and zero reboiler heat duty operation were the most economical operation conditions, and that energy reduction of 62% compared to the conventional distillation column is achievable under these conditions. With the HIDiC simulator developed, a process flow involving heat exchange between the overhead vapor and the feed was studied, and the possibility of further energy-saving operation of the HIDiC was suggested.
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  • Nobuhide Takahashi, Hiroshi Mano, Kazuhiro Okabe, Miho Nakamura, Yuich ...
    Type: Research Papers
    2008 Volume 34 Issue 1 Pages 76-84
    Published: January 20, 2008
    Released: February 06, 2008
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    Use of a hollow fiber membrane for chemical absorption of CO2 is expected to significantly reduce the volume and construction cost of equipment in comparison with a conventional packed tower. In the present study, experiments to examine the effects of membrane properties on CO2 absorption performance were performed using a counterflow-type hollow fiber membrane contactor. The membrane materials employed were PTFE, PP and PE; and 30 wt% MEA aqueous solution was used as an absorbent of CO2. In addition, a simulation model was developed to examine the effects theoretically.
    Except for the drawn membrane of PE, the measured values of total mass transfer coefficient and CO2 recovery rate were in good agreement with the values predicted by the simulation, proving the validity of the simulation model developed in this study. The hollow fiber membranes of PP and PE showed high CO2 recovery rates of 80–90%. On the other hand, the hollow fiber membranes of PTFE were larger in diameter and thickness, resulting in the lowest CO2 recovery rates. In the case of PTFE, CO2 recovery rate increased with increasing pore diameter of membrane, which was theoretically supported by the simulation model, while it decreased with increasing pore diameter in most cases of PP and PE.
    The drawn membranes of PE showed remarkably high CO2 recovery rates near 100%, indicating that the drawing treatment of hollow fiber membranes was very effective in enhancing mass transfer through them.
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  • Hidetada Nagai, Ko Kuwabara, Giorgio Carta
    Type: Research Papers
    2008 Volume 34 Issue 1 Pages 85-94
    Published: January 20, 2008
    Released: February 06, 2008
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    A simulation model describing L-lysine behavior in multicolumn cation exchange separation was developed and used to investigate the effect of column number in adsorption and desorption of counter-current multicolumn systems.
    DIAION SK-1B was used as an example of cation exchange resin, which has 8% of DVB content. L-lysine dissociation constants, ion exchange equilibrium constants and intraparticle diffusivities were measured at 25°C. These fundamental parameters were applied for multicolumn simulation. All calculated results were obtained for a column of 1.5 cmφ×10 cm and switching time of 3600 s.
    1. In the case of single-column adsorption, L-lysine leakage in the adsorption train was observed at a feed rate of 5.7×10−2 mol/h of L-lysine when monovalent lysine solution was fed to the multicolumn system. Two- and three-column adsorption systems showed L-lysine leakage at feed rates of 1.2×10−1 mol/h and 1.4×10−1 mol/h of L-lysine, respectively. Thus, the increase of column number from 1 to 2 was effective for prevention of the leakage, while the increase of column number from 2 to 3 was not effective.
    2. In the case of single-column elution, L-lysine was not completely desorbed at any feed rate of ammonia into the system. Two- and three-column desorption systems showed similar results, with complete L-lysine desorption at feed rates of 6.6×10−2 mol/h and 1.0×10−1 mol/h of ammonia, respectively.
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  • Takashi Aida, Takanori Yotsumoto, Kaori Kimura, Ratanaporn Yuangsawad
    Type: Research Papers
    2008 Volume 34 Issue 1 Pages 95-101
    Published: January 20, 2008
    Released: February 06, 2008
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    Oxidative removal of a low concentration of CO from hydrogen was studied using a simulated moving bed reactor (SMBR) with 1wt% Pt/Al2O3 as a catalyst and adsorbent. Compared with an ordinary fixed bed reactor (FBR), SMBR showed higher CO removal when the ratio of the CO introduction rate to the active site moving rate (mCO) was smaller than 1. The presence of H2 enhanced the CO oxidation performance of FBR, whereas it barely affected the performance of SMBR. Effects of mCO, ratio of O2 introduction rate to active site moving rate (mO2), H2 concentration and O2 concentration on CO removal and COx concentration in H2 at the outlet of SMBR were investigated experimentally. The most important factor in order to enhance the CO removal was mCO: CO was not detected at the outlets when mCO was smaller than 1. The most important factor in order to enhance the COx concentration in H2 at the outlet was mO2: CO2-free H2 was obtained when mO2 was larger than 1. H2 concentration did not affect either the CO removal or the COx concentration in H2 at the outlet. O2 concentration affected mCO and mO2, which in turn influenced the CO removal and COx concentration in H2 at the outlet.
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  • Takafumi Horie, Takashi Aida
    Type: Research Papers
    2008 Volume 34 Issue 1 Pages 102-107
    Published: January 20, 2008
    Released: February 06, 2008
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    Forced composition cycling was conducted for oxidative coupling with Bi2O3–P2O5 in a microreactor in order to obtain high benzene yield and suppress CO2 production. A microreactor suitable for controlling flow was thought to work effectively in conducting forced composition cycling because it restrains axial diffusion. The results for cyclic operation of the microreactor and a packed bed reactor were compared on the basis of relaxation time. With the microreactor, forced composition cycling in a short period, 12 s, could be carried out. Although the shapes of the response curves for the microreactor (period: 12 s) and the packed bed reactor (period: 72 s) were similar when the periods were normalized, those of product yields were different. This is because the response to composition change was so accurate that the catalyst was kept in a high oxidation state. The maximum value of benzene production by forced composition cycling with the microreactor was about 4 times that of the steady state and about 2 times the maximum value of benzene production by forced composition cycling with the packed bed reactor.
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  • Ken-ichiro Sotowa, Nobumasa Shiraishi, Shigeru Sugiyama
    Type: Research Papers
    2008 Volume 34 Issue 1 Pages 108-112
    Published: January 20, 2008
    Released: February 06, 2008
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    The present study aims at developing a new chemical reactor for forced temperature cycling at a low energy cost. Forced temperature cycling is an attractive mode of chemical reactor operation, since it can achieve higher conversion and selectivity for a variety of chemical reactions than steady-state operations. However, there are only limited number of experimental investigation on the effects of forced temperature cycling on chemical reactions. This is because a large amount of energy is needed to quickly change the reactor temperature. With the reactor developed in this study, only 9 W of electric energy was required to achieve forced temperature cycling. In a sample case of the cycling operation for propylene oxidation, it was demonstrated experimentally that the selectivity and conversion can be controlled by employing the forced temperature cycling.
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  • Qi Zhang, Yu Guo, Lu Zhou, Makuto Sakurai, Hideo Kameyama
    Type: Research Papers
    2008 Volume 34 Issue 1 Pages 113-118
    Published: January 20, 2008
    Released: February 06, 2008
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    A plate methane steam reformer, consisting of closely spaced plates of electrically heated alumite catalyst (EHAC), has been numerically investigated from the viewpoint of heat and mass transfer. Based on the ordinary heat exchange reformer where endothermic and exothermic reactions take place in alternative chambers, a novel reformer was proposed by integrating a preheating chamber with the combustion chamber. The simulation results predicted that the novel reformer could be started up by electrical heating through the catalyst, even with the inlet combustion gas temperature of 298 K. In addition, the response to load fluctuation has also been numerically investigated. When the feed flow was increased to 1.5 times, a fast response to the load fluctuation was observed, which was attributed to the excellent heat transfer performance of the plate reactor.
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  • Hideaki Tsuneki
    Type: Research Papers
    2008 Volume 34 Issue 1 Pages 119-124
    Published: January 20, 2008
    Released: February 06, 2008
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    The demand for diethanolamine as a raw material for herbicides has been increasing, and a selective production process for diethanolamine is required. We found that pentasil-type zeolite modified with a rare earth element was an excellent catalyst with high activity and diethanolamine selectivity, and commercialized the process using this catalyst. The catalyst is deactivated in several days, so regeneration of the catalyst is necessary. Analysis and modeling of catalyst deactivation are necessary for industrial process design and for determination of operation conditions. We analyzed deactivated catalysts and catalyst-bed temperature profile change in relation to ethylene oxide conversion, and proposed a model in which cumulative reaction amount of ethylene oxide and diethanolamine corresponds to catalyst deactivation. This model can explain the change of temperature profile and product distribution, and is useful for reaction process design.
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  • Naoto Ohmura, Yuka Zenitani, Koudai Nagata, Norihisa Kumagai, Teiji Ta ...
    Type: Research Papers
    2008 Volume 34 Issue 1 Pages 125-129
    Published: January 20, 2008
    Released: February 06, 2008
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    The present work investigated the effect of mixing and pH of solution on latex particle coagulation from the aspect of process intensification. Experiments were conducted in a CSTR under conditions below the critical micelle concentration of emulsifier in order to reduce emulsifier consumption. When the rotational number of a 2-bladed impeller of half-moon shape was varied as a control parameter, the reaction state depended on mixing below 200 rpm. Under these mixing conditions, the monomer conversion was low and particle coagulation was suppressed. On the other hand, at above 200 rpm the reaction state was controlled by polymerization reaction, and high monomer conversion was obtained irrespective of the rotational number of impeller. These mixing conditions enhanced particle coagulation, and larger particles were obtained. When pH of solution was varied as the other control parameter, higher pH values (pH=6 and 7) enhanced particle coagulation, the mean particle size increased up to 3 μm with time and particles of larger than 10 μm were observed in the sample obtained at the maximum mean particle size. Under these conditions, a bimodal particle size distribution was obtained in the process of particle growth to the maximum mean diameter, while a mono-dispersed distribution was obtained in the process of decreasing mean particle size from the maximum value.
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  • Satoko Fujioka, Hideyuki Matsumoto, Chiaki Kuroda
    Type: Research Papers
    2008 Volume 34 Issue 1 Pages 130-135
    Published: January 20, 2008
    Released: February 06, 2008
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    An unstable oscillatory phenomenon induced by local change of property in a shear flow with an exothermic reaction was investigated. Effects of viscosity on patterns of oscillation were quantitatively analyzed by applying analysis/modeling methods with different viewpoints. A timed Petri Net based on the qualitative model of the oscillation was used for a qualitative simulation. It was confirmed that the frequency of oscillation near a point of occurrence increased with increase of viscosity. In a transition area where oscillatory patterns complicatedly change in the direction of flow, it is difficult to use a systematic method like a Petri Net for a quantitative analysis of complex oscillatory patterns. Therefore Fractal analysis was applied based on the visualized oscillatory patterns, and the effects of viscosity were investigated. It was confirmed that viscosity was an important parameter also in the transition area of oscillatory patterns. In this unstable oscillatory phenomenon, the oscillatory pattern is considered to occur based on a strong interaction of momentum and heat transfer that have different time scales. For the prediction of oscillatory flow patterns by using the temperature fluctuation data, effects of viscosity on the temporal patterns of temperature oscillation were investigated. Fractal analysis of time series was introduced, and it was also confirmed that viscosity was an important parameter for the control of oscillatory patterns of temperature. Characteristics of spatial patterns and temporal patterns of the oscillation in the area of occurrence and transition were extracted respectively by using analysis/modeling methods with different viewpoints. In future work, the dynamics of the oscillation should be simulated by the integration of those analysis/modeling methods to predict the state of oscillatory flow in the reactor by the measurement of temperature.
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  • Hideyuki Matsumoto, Naoki Miyamoto, Daisuke Kobayashi, Chiaki Kuroda
    Type: Research Papers
    2008 Volume 34 Issue 1 Pages 136-143
    Published: January 20, 2008
    Released: February 06, 2008
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    For the continuous operation of emulsion polymerization of styrene using ultrasound, the system structure for indirect ultrasonic irradiation was investigated. From examination of the structure of flow reactor that could utilize ultrasound field, it was found to be necessary for the reactor design to consider the configuration of the bottom facing the transducer, the method for supply of nitrogen gas, and the liquid level inside the reactor. Consequently, application of a perpendicular cylindrical reactor was proposed, which was effective for the indirect irradiation system.
    Next, the dynamic behavior of a continuous polymerization system employing the above-mentioned reactor model was analyzed. It was found that the flow operation based on an appropriate mean residence time resulted in lower polydispersity of the product than the batch operation. Moreover, it was demonstrated that application of a recycling system and modification of the system structure could intensify the process using ultrasonic irradiation.
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  • Takao Ohmori, Weifang Yu, Sho Kataoka, Takuji Yamamoto, Akira Endo, Ma ...
    Type: Notes
    2008 Volume 34 Issue 1 Pages 144-147
    Published: January 20, 2008
    Released: February 06, 2008
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    Process intensification of a membrane rector for hydrogen production using methane steam reforming under a periodic operation was investigated via numerical simulation. In the periodic operation used, the reactor wall temperature was set to vary sinusoidally along its axis. As a result, we found that the hydrogen production rate can be increased by 7% using the appropriate wall temperature modulation. The factors of the improvement in efficiency that give rise to the process intensification were also discussed from the viewpoint of optimizing reactions and/or transport phenomena in every part of the process.
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  • Hidetoshi Sekiguchi, Ryusuke Zushi
    Type: Notes
    2008 Volume 34 Issue 1 Pages 148-151
    Published: January 20, 2008
    Released: February 06, 2008
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    The production of H2O2 as an environmentally benign chemical was attempted using underwater electrical discharge with ultrasonic irradiation to examine the synergic effects of ultrasound and plasma. The results showed that H2O2 production was reduced, while the production efficiency based on the energy consumption for the discharge was improved. The study suggested that ultrasonic irradiation may be an effective method to intensify processes in underwater electrical discharge.
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  • Hidetoshi Sekiguchi, Hisashi Ito
    Type: Notes
    2008 Volume 34 Issue 1 Pages 152-155
    Published: January 20, 2008
    Released: February 06, 2008
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    The non-catalytic amination of 1-decene using atmospheric pressure non-thermal plasma was investigated. The reaction was carried out by exposing ammonia plasma jet to liquid 1-decene. The products identified included 1-decylamine and 2-decylamine, as well as decane. A reaction mechanism was proposed from the results obtained. The study suggested the atmospheric pressure non-thermal plasma jet was attractive for the amination of organic compounds having carbon double bond without use of a catalyst.
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Particle Engineering
  • Nobusuke Kobayashi, Yasuyuki Ueda, Yuri Ohshika, Kenji Mizuno, Shigeo ...
    Type: Research Papers
    Subject area: Particle Engineering
    2008 Volume 34 Issue 1 Pages 156-160
    Published: January 20, 2008
    Released: February 06, 2008
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    A continuous type vibration mill was developed for the effective pulverization of woody biomass. A conventional vibration mill was upgraded the continuous pulverization system to increase woody biomass pulverization yield. To increase the yield, a weir was mounted at the exit of the vibration cylinder, by which the pulverization time was controlled. A closed pulverization system was also developed to increase the throughput of woody powder. As a result, the upgraded continuous type vibration mill was able to improve the yield of woody powder and pulverization efficiency dramatically.
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Thermal Engineering
  • Takuji Harada, Hirotatsu Watanabe, Yohsuke Matsushita, Shoji Tanno, Hi ...
    Type: Research Papers
    Subject area: Thermal Engineering
    2008 Volume 34 Issue 1 Pages 161-167
    Published: January 20, 2008
    Released: February 06, 2008
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    Secondary atomization in emulsified fuel is widely accepted to explain a decrease in NOx, CO and soot emissions. Although secondary atomization of emulsified fuel droplets is known to be stochastic, little detailed information is available on this behavior. In this paper, the effect of emulsified fuel droplet temperature and initial diameter on secondary atomization was investigated. The purpose of this study was to reveal the occurrence conditions of vapor outbreak (puffing), which is a form of secondary atomization. A water/n-dodecane emulsified fuel droplet suspended from a thermocouple was set into an electric furnace, and secondary atomization of the droplet was observed by using a hi-speed camera. The effects of the initial diameter of the water/n-dodecane emulsified fuel droplet and wall temperature of the furnace were also investigated. As a result, the probability of puffing increased with an increase in furnace wall temperature and the initial diameter of the emulsified fuel droplet.
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Process Systems Engineering and Safety
  • Hajime Eguchi
    Type: Research Papers
    Subject area: Process Systems Engineering and Safety
    2008 Volume 34 Issue 1 Pages 168-174
    Published: January 20, 2008
    Released: February 06, 2008
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    Production Support Systems (PSS) in the chemical factory are considered to contribute to improved productivity and increased sales of products by speeding up production. Recently, however, doubt has been cast on the cost-efficiency of investment in these systems, so the introduction of new PSS and development of new functions have been slowing down. Nevertheless, PSS based on process systems engineering are expected to play important roles in raising the productivity of chemical factories and it is not desirable to suspend the development of the basic functions of PSS. In this paper, a new criterion of efficiency based on labor-saving effect is proposed instead of the conventional estimate of return on investment in PSS. In order to explain the procedure, an example of the estimation for a chemical process is shown.
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Micro and Nano Systems
  • Yoshikazu Yamasaki, Masato Goto, Akira Kariyasaki, Shigeharu Morooka
    Type: Research Papers
    Subject area: Micro and Nano Systems
    2008 Volume 34 Issue 1 Pages 175-180
    Published: January 20, 2008
    Released: February 06, 2008
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    In developing unit operations for microreactor systems, an Archimedean microchannel was fabricated and used to separate solid particles (glass beads of 22 and 40 μm in diameter) from water. The spiral channel was 700 μm in width and 500 μm in height, with an innermost radius of 2.5 mm, and an outermost radius of 5.0 mm, and was held either horizontally or vertically. After 2.5 turns, the channel was bifurcated to the outlets. The slurry was introduced into the inner end of the microspiral. Solid particles moved along with the secondary flow (Dean vortex), and, at the same time, ascended to the lower walls due to gravity. The samples recovered at the outlets were dried and weighed, and the separation factor of particles was determined.
    Horizontal orientation: When the sedimentation velocity of the particles was higher than the central velocity of the secondary flow, particles were concentrated in the inner bottom corner of the channel.
    Vertical orientation: In this study, the outlets were located at an angle of 90° relative to the top of the channel. Concentration of solid particles varied along the direction of the liquid flow. Since the bifurcated outlets were located in the downward liquid flow region, solid particles were concentrated on the inner wall of the channel.
    CFD simulation was also performed. The calculation was approximately in agreement with the experiment. Calculated distributions of liquid and particle velocities, as well as those of particle concentration in the microchannel, gave beneficial suggestions for the design and operation of microspirals applicable to liquid/solid separation.
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Materials Engineering and Interfacial Phenomena
  • Takanori Watanabe, Michio Nawata, Jun Kobayashi, Noriyuki Kobayashi, M ...
    Type: Research Papers
    Subject area: Materials Engineering and Interfacial Phenomena
    2008 Volume 34 Issue 1 Pages 181-186
    Published: January 20, 2008
    Released: February 06, 2008
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    Fine particle production by emulsion combustion at high temperature was investigated to produce small phosphor particles with high luminance. In this study, Y2O3 : Eu particles of red fluorescence material were synthesized, and the effect of the process on its luminescence and structural characteristics were evaluated. A mixed solution of yttrium and europium nitrate and white kerosene were used as raw materials. W/O (water-in-oil) and W/O/W (water-in-oil-in-water) emulsions were prepared by stirring these raw materials and surfactants in an ultrasonic homogenizer. The production of phosphor particles was carried out by burning the emulsions in a high temperature furnace. The mean particle diameter of produced phosphor was less than 100 nm. The diameter of the particles made with the W/O/W emulsion was smaller than the estimated value based on the size distribution and concentration of the dispersed solution phases. Moreover, the luminescence intensity of the particles produced by the proposed process was 1.5 times that of the particles without emulsion combustion. However, the value for particles made from the W/O/W emulsion was approximately 45% of the phosphor made by a conventional method. More investigation on improvement of the luminescence is necessary.
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  • Masaaki Oda, Shinichiro Suga, Hidefumi Yoshii, Takeshi Furuta
    Type: Research Papers
    Subject area: Materials Engineering and Interfacial Phenomena
    2008 Volume 34 Issue 1 Pages 187-193
    Published: January 20, 2008
    Released: February 06, 2008
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    An innovative multi-layer coating method has been studied for preparation of gradient refractive index (GRIN) lenses. The preparation method employs a polymer optical fiber as a core fiber, which is subjected to a repeated process of alternating peripheral coating with polymer solutions of different refractive indices (RIs). Three polymer solutions with different RIs were used as coating solutions. The coating behavior of the polymer solutions on the periphery of the core fiber was studied by use of continuous multi-coating equipment. Regression analysis showed that the dimensionless coating thickness was well correlated with the capillary number, Ca, being proportionally dependent on Ca to the two-third power. The coating thickness was also dependent on the depth of the polymer solution in the reservoir.
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Environment
General Research and Others
  • Katsuhiko Sugimori, Yoshitomo Tawarayama, Takayuki Sato, Takamine Imad ...
    Type: Research Papers
    Subject area: General Research and Others
    2008 Volume 34 Issue 1 Pages 200-204
    Published: January 20, 2008
    Released: February 06, 2008
    JOURNALS RESTRICTED ACCESS
    In order to prevent hazardous contamination inside satellite stations by the sediment action of frozen toxic liquid propellant on the space suits of astronauts, it is necessary to understand the phase changes of the leaked liquid propellant in case of valve breakdown. Using MON-3 as the liquid propellant, the minimum flow rate of MON-3 released without freezing to the vacuum chamber was investigated. For all the experimental flow rates tested in this study (0.347×10−5−4.45×10−5 g/s), MON-3 was found to freeze when released into the vacuum chamber. Freezing may be caused by the loss of latent heat to the surroundings in the vicinity of the orifice outlet where vaporization occurs.
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