All issues
Volume 34, Issue 6
Displaying 1-18 of 18 articles from this issue
- |<
- <
- 1
- >
- >|
Transport Phenomena, Fluid Mechanics and Mixing
-
ZDZISLAW JAWORSKI, JAN DUDCZAK2001 Volume 34 Issue 6 Pages 715-723
Published: 2001
Released on J-STAGE: April 26, 2002
JOURNAL RESTRICTED ACCESSBatch mixing of a tracer in a stirred tank was simulated by means of a commercial CFD code and the probability distribution of the tracer concentration was studied. Two mixer configurations along with three modes of tracer addition were examined. It is found that the effect of the mixer configuration on the values of the probability density function is manifested virtually throughout the entire process, whereas that of the addition mode gradually diminishes as the process progresses. The effect of the scale of scrutiny on the concentration distribution was analysed using five scale levels and its importance is confirmed in the initial period of homogenisation. The applicability of the beta function to model the probability density function obtained numerically was evaluated. It is concluded that the beta model does not fully reflect the distribution complexity.View full abstractDownload PDF (97K) -
KAZUHIRO SHIMIZU, MITSUO KAMIWANO, MEGURU KAMINOYAMA, KAZUHIKO NISHI2001 Volume 34 Issue 6 Pages 790-801
Published: 2001
Released on J-STAGE: April 26, 2002
JOURNAL RESTRICTED ACCESSIn the present work, for expression and evaluation of characteristics of the drop size distribution, we propose the indices of representative diameter, Ds*, sharpness, Ss* and skewness, Sa. We investigated the drop size distributions with varying dispersed phase concentrations and impeller speeds as stirred operation condition factors in various impeller stirred tanks using a real-time high-speed image processing system, which was developed by ourselves. From the drop size distribution obtained, we discuss quantitatively the characteristics of the drop size distribution in various impeller stirred tanks with three defined indices. As a result, it is found that the defined indices can express and be used to evaluate more accurately the drop size distribution over a wide range of dispersed phase concentrations and impeller speeds. It is also found that three-dimensional plots showing the dependence of the defined indices on the dispersed phase concentration and the impeller speed as stirred operation condition factors can express and be used to evaluate the characteristics of the liquid-liquid dispersion conditions in each stirred tank. Furthermore it is found that the relationship between the defined indices and the dispersed phase concentration for constant power consumption per volume can be used to discuss the quality of performance of the liquid-liquid dispersions in various impeller stirred tanks.View full abstractDownload PDF (209K) -
YASUSHI KOITO, KOTARO TAGAWA, YASUHIRO MARUTA, KAZUYOSHI TANAKA, OSAMU ...2001 Volume 34 Issue 6 Pages 819-827
Published: 2001
Released on J-STAGE: April 26, 2002
JOURNAL RESTRICTED ACCESSExperimental and numerical analyses are conducted to investigate the effect of the size of a formstable phase change material (FS-PCM) on discharge characteristics of packed-bed latent heat storage columns. Two types of cross-linked polymer pellets having different dimensions are used as the FS-PCM and water is used as the heat transfer fluid (HTF). Experimental results on the heat transfer in the packed bed of each FS-PCM and the discharge characteristics of the packed bed are reported. By using the empirical equations for estimating the heat transfer coefficient between the FS-PCM and the HTF obtained in the present experiment, the transient variation of the temperature of the HTF at the outlet of the packed bed is calcualted with a numerical method, and they agree with the experimental results under various operating conditions. It is also shown that by increasing the contact time between the FS-PCM and the HTF in the packed bed, the demerits caused by the thermal resistance in the FS-PCM and between the FS-PCM and the HTF are overcome.View full abstractDownload PDF (192K)
Materials and Devices
-
CHUNG-KUNG LEE2001 Volume 34 Issue 6 Pages 724-730
Published: 2001
Released on J-STAGE: April 26, 2002
JOURNAL RESTRICTED ACCESSEffects of calcination temperature on the surface irregularity and pore connectivity of sol-gel processes derived TiO2 have been investigated based on the fractal and percolation analysis of their nitrogen isotherms, respectively. Fractal analysis suggested that the surface rugosity of TiO2 may be described as self-affine instead of self-similar and that thermal effects may induce a slight increase on the surface roughness despite a large reduction of BET surface area and pore volume. On the other hand, percolation analysis reported that the mean coordination number of pore network of TiO2 samples covered the range of 2.1-2.7 and thermal effects may slightly decrease this value.View full abstractDownload PDF (97K) -
YASUMASA TAKAO, MUTSUO SANDO2001 Volume 34 Issue 6 Pages 828-833
Published: 2001
Released on J-STAGE: April 26, 2002
JOURNAL RESTRICTED ACCESSThis short communication offered one of flame aerosol synthesis of aluminum nitride, AlN, as a new filler-powder supply-route for resin polymer composite system filled with ceramic particles, which would have a promising advantage in thermal conductivity. Flame AlN synthesis was based on the aerosol preparation of conventional LPG-O2-N2-NH3 system flame, and the particulate raw material. Effects of flame temperature and heat amount were studied on the direct-nitridation of Al through CH4, C3H8, C2H2 flame of LPG-O2-N2-NH3 system. As-prepared resultants were consisted of an Al-O-N system and a remained Al raw material, and their annealed powder was comprised of an AlN majority and a little α-Al2O3. Heating amount increments resulted in the yield-increase of polyphasic intermediate system of Al-O-N and that of AlN. Flame synthesized powder had a fairly large aerosol particle size, roughly 10 μm in average size, and a bimodal size distribution. Especially, the new AlN powder had a non-squarish shape rather than one of marketed products with angular morphology, which would be good for high-density packing. Feasible potential of this synthesis method was confirmed to provide the AlN powder having suitable properties as the filler-powder.View full abstractDownload PDF (185K)
Separations
-
MIKIHIRO NOMURA, YASUYUKI MINETA, NAOKO YAMAGUCHI, EIICHI KIKUCHI, KOI ...2001 Volume 34 Issue 6 Pages 731-736
Published: 2001
Released on J-STAGE: April 26, 2002
JOURNAL RESTRICTED ACCESSA novel organic-ceramic membrane having stable Si-C bonds was developed for separation of high temperature organic solutions. Porous vycor glass was employed for a substrate which was modified by a series of chemical vapor deposition (CVD) and hydrosilylation. 1,3,5,7-Tetramethylcyclotetrasiloxane (H4) was used as a CVD source in order to introduce Si-H bonds on the surface of porous vycor glass. The Si-H bonds were then catalytically hydrosilylated with olefins. As a result, organic functional groups were introduced via Si-C bonds. A compact membrane was obtained when CVD treatment was carried out at 343 K. The membrane that was modified by the hydrosilylation of styrene showed benzene permselectivity in benzene/cyclohexane vapor permeation test at 373 K. The separation factor of benzene over cyclohexane was 2.9 and benzene flux was 1.2 × 10-8 mol m-2s-1Pa-1, and the permeation properties are stable for more than 1000 min at 373 K.View full abstractDownload PDF (158K) -
SHR-PING LIN, CHUN-I LIN, HSI-KUEI CHEN2001 Volume 34 Issue 6 Pages 737-742
Published: 2001
Released on J-STAGE: April 26, 2002
JOURNAL RESTRICTED ACCESSBleaching of sesame oil with acid activated rice hull ash was investigated. Lovibond color indices of sesame oils before and after bleaching with the ash were determined to calculate the bleaching efficiency of the ash. Experimental results indicated that the ratio of rice hull ash/acid, agitation speed of activation and pH value of ash had no effect on the bleaching efficiency in the ranges of variables studied. Increase in activation temperature might increase the bleaching efficiency slightly when the temperature was low. When it was over 30°C, the efficiency remained constant. Bleaching efficiency was found to increase significantly with the ratio of rice hull ash/sesame oil. When the bleaching temperature was increased, the efficiency was found to increase slightly, reach a maximum at 120°C and then decrease. Increase in agitation speed of bleaching might increase the efficiency slightly. But it levelled off when the speed was over 80 rpm. The bleaching efficiency remained constant initially and reduced slightly with bleaching time when it was longer than 30 min.View full abstractDownload PDF (80K) -
TORU TAKASHINA, SHINTARO HONJO, NAOHIKO UKAWA, TSUYOSHI OISHI2001 Volume 34 Issue 6 Pages 810-818
Published: 2001
Released on J-STAGE: April 26, 2002
JOURNAL RESTRICTED ACCESSTo investigate the mechanism of SO2 absorption with the chemical reaction in the limestone-gypsum process, the effect of limestone concentration and particle size on the SO2 absorption rate in limestone slurry was studied by using a stirred tank reactor at a constant pH and high temperature (50°C). An absorption model with a reaction plane based on the film model was also proposed for an actual flue gas desulfurization (FGD) plant. For the SO2 absorption rate depending on the concentration and particle size of limestone powder, the experimental values agreed quite well with the results calculated with the absorption model, regarding the limestone dissolution rate within the liquid.View full abstractDownload PDF (109K) -
HIROSHI YOSHIDA2001 Volume 34 Issue 6 Pages 840-843
Published: 2001
Released on J-STAGE: April 26, 2002
JOURNAL RESTRICTED ACCESSUsing a batch type experimental apparatus for electro-osmotic dewatering, it was previously confirmed that an electric field applied intermittently was available for efficient performance of its dewatering. In this study, a cross-flow continuous type experimental apparatus, which was constituted of two vertical cylindrical electrodes, was made and used for electro-kinetic dewatering of slurry. The effect of the electric field that is intermittently applied to the slurry flowing down between the cylindrical electrodes was investigated experimentally. It is shown that the amount of removed water per electric power consumption under the intermittent electric field was much larger than that under continuous DC, and that the intermittent power application was also available in such a cross-flow continuous type apparatus.View full abstractDownload PDF (170K) -
TOSHINORI TSURU, TERUTAKA TOYOSADA, TOMOHISA YOSHIOKA, MASASHI ASAEDA2001 Volume 34 Issue 6 Pages 844-847
Published: 2001
Released on J-STAGE: April 26, 2002
JOURNAL RESTRICTED ACCESSA new type of photocatalytic reaction system, in which filtration and a photocatalytic reaction occur simultaneously, is reported. The concentration of trichloroethylene (TCE) in permeate stream decreased by approximately 5 ppm while TCE permeating porous TiO2 membranes under conditions of blacklight irradiation. In addition, membrane fouling by polyethyleneimine, which caused a decrease in permeate flux, was also found to be reduced by photocatalytic reaction.View full abstractDownload PDF (41K)
Process Systems Engineering
-
HSIAO-PING HUANG, MING-WEI LEE, CHUN-YUN TSAI2001 Volume 34 Issue 6 Pages 748-756
Published: 2001
Released on J-STAGE: April 26, 2002
JOURNAL RESTRICTED ACCESSA block-oriented nonlinear system consists of a series of blocks. These blocks represent both memoryless nonlinearity and linear dynamics that comprise the overall input-output dynamics of the system. Under this category, the nonlinear systems are represented as Wiener-, Hammerstein-, Wiener-Hammerstein, and Hammerstein-Wiener type of models, etc. Since methods used to estimate the parameters vary with different types of model, structure identification becomes an essential step in identification. In this article, a strategy based on the results of consecutive relay feedback experiments is proposed to select a model among those block oriented ones aforementioned. After the model structure has been determined, estimation of parameters can then proceed. A few example processes are used to illustrate the identification by this proposed method.View full abstractDownload PDF (112K) -
BYOUNGGWAN KANG, JUNG CHUL SUH, MASAHIDE WAKAKURA, EN SUP YOON2001 Volume 34 Issue 6 Pages 802-809
Published: 2001
Released on J-STAGE: April 26, 2002
JOURNAL RESTRICTED ACCESSIn this article, a strategy for automatic hazard analysis of batch process and the integrated automatic hazard analysis systems are proposed. The suggested process models for hazard analysis are based on multimodeling approach, which aims the improvement of the effectiveness and efficiency of reasoning process by cooperation of multiple models. According to the multimodeling concept, four process representation models, including operational, material, behavioral and functional knowledge bases, and four hazard inference algorithms are established. For a case study, a batch pharmaceutical process is tested and a maloperation analysis is performed, and the case study showed more successful capture of hazard information using the devised analysis system than the traditional systemsView full abstractDownload PDF (214K)
Biochemical, Food and Medical
-
MAHMOOD FARSHBAF, YOSHIHIRO KATOH, TAKEO MORIMOTO, TARO UDAKA, TOMOHIS ...2001 Volume 34 Issue 6 Pages 743-747
Published: 2001
Released on J-STAGE: April 26, 2002
JOURNAL RESTRICTED ACCESSRefolding of CAB was studied at high concentrations of protein and urea. Aggregate formation was decreased by using higher concentrations of urea in refolding buffer. Refolding yields of 60% were obtained at high concentrations of CAB by using urea concentrations of 3.0-4.0 M in renaturation mixture. Comparison of the refolding yield and the amount of soluble CAB in renaturation mixture indicated that the apparent specific activity of refolded CAB was lower than that of native one at higher concentrations of urea. Difference in the steric structures of native and refolded CAB was observed in CD spectra of these samples. However, removal of urea from loosely folded CAB solution by dialysis recovered the native structure of CAB, as well as its native specific activity. Hence the refolding efficiency after dialysis was improved to about 70-80% at CAB concentrations of 3-5 kg/m3. Effect of incubation time of renaturation mixture before dialysis was studied, and it was shown that incubation time less than 3 hours increased aggregate formation and decreased the refolding yield. Therefore, formation of more stable intermediates in the refolding pathway decreases aggregate formation during urea removal. These results lead to a consecutive dilution-dialysis method for refolding at high concentrations of proteins.View full abstractDownload PDF (54K) -
SHINJI SUGIURA, MITSUTOSHI NAKAJIMA, HIDEKI USHIJIMA, KOJI YAMAMOTO, M ...2001 Volume 34 Issue 6 Pages 757-765
Published: 2001
Released on J-STAGE: April 26, 2002
JOURNAL RESTRICTED ACCESSMicrochannel (MC) emulsification is a novel technique for preparing monodispersed emulsions. This study investigates the preparation of monodispersed water-in-oil (W/O) emulsions by means of a hydrophobic MC. The effects of surfactants, the properties of continuous oil phases and the flow velocity of the dispersed water phase through the channels on the MC emulsification were studied. The surfactants should be dissolved in the continuous oil phase to create water droplets from the MC without continuous outflow. There was an optimal HLB of surfactant for the monodispersity and stability of the prepared emulsions. Hexaglycerin pentaoleate (PO-500; HLB, 4.9) was found to be suitable for preparing the stable water-in-ethyl oleate emulsion and water-in-tetradecane emulsion. The average diameters and the coefficients of variation of the prepared emulsions were 27.4 μm and 20.6% for the water-in-ethyl oleate emulsion, and 19.1 μm and 4.2% for the water-in-tetradecane emulsion. Hexaglycerin condensed ricinoleic acid ester (HGCR) was suitable for preparing stable water-in-triolein emulsions. The average diameter and coefficient of variation of the emulsion were 39.8 μm and 6.5%. The effects of the viscosity and the hydrophobicity of the continuous oil phase were investigated. Monodispersed emulsions were prepared in the hydrophobic oil phases because hydrophobic oil phases prevent wetting of the MC plate with the water phase. The droplet diameter increased with an increase in viscosity of the continuous oil phase. When the high-viscosity continuous oil phase was used, droplet diameter increased with an increase in the flow velocity of the dispersed water phase through the channel.View full abstractDownload PDF (182K) -
HIROKAZU KIKUTA, KENJIRO KANO, HIROYUKI HONDA, TAKESHI KOBAYASHI2001 Volume 34 Issue 6 Pages 848-851
Published: 2001
Released on J-STAGE: April 26, 2002
JOURNAL RESTRICTED ACCESSBovine cathepsin C (CTC) production from a recombinant methylotrophic yeast Candida boidinii CT714 was investigated, in which CTC gene was driven by formate dehydrogenase promoter and strongly induced in the presence of methanol. Two step fermentation using DYS medium containing 1.0% (w/v) glucose for cell growth and MYS medium containing 2.5% (v/v) methanol for inducible production of CTC was suitable for efficient production. Methanol concentration within 1.5 to 3.5% (v/v) was preferable for CTC induction. After 24 h of cell growth and 72 h of induction, CTC production reached approximately 12 U/I (this corresponded to 2.15 U/g-dry cells). When vitamins were enriched in growth medium, CTC productivity was improved more than 3 times higher, and it was found that the effective vitamins were biotin, p-aminobenzoic acid and thioctic acid.View full abstractDownload PDF (37K)
Safety, Environment and Energy
-
KWANG-HEE LIM2001 Volume 34 Issue 6 Pages 766-775
Published: 2001
Released on J-STAGE: April 26, 2002
JOURNAL RESTRICTED ACCESSIt has been reported that highly adsorptive granular activated carbon improves the biofilter performance. In this work the effect of adsorption property of the medium, on the biofilter capacity of eliminating organic components in waste gas streams is theoretically discussed using a biofilter model. In this first paper adsorption capacity is assumed to be in excess and steady-state solutions are compared with Ottengraf's solutions in various limiting situations. When first-order kinetics is used in the substrate utilization rate, as the value of α increases, the corresponding values of the dimensionless pollutant concentration in a biofilm and the dimensionless pollutant concentration in waste-gas streams through a biofilter become lower at a given value of Thiele modulus, through the thickness of the biofilm and the height of the biofilter, respectively. However, the effect of α becomes insignificant when the value of Thiele modulus becomes larger than a certain number. With zero order kinetics in the substrate utilization rate, for both situations of reaction limiting and diffusion limiting, their steady-state solutions are obtained.View full abstractDownload PDF (125K) -
KWANG-HEE LIM2001 Volume 34 Issue 6 Pages 776-789
Published: 2001
Released on J-STAGE: April 26, 2002
JOURNAL RESTRICTED ACCESSMathematical models for waste air treatment with a biofilter (part 1) are modified for the case that the adsorption capacity is limited. With the aid of process lumping the governing equations of unsteady states are solved analytically for the simple and easy utilization of a biofilter in industrial operations. Adopting clouding effect in κa in order to explain reversible adsorption processes when the adsorption capacity is limited as the adsorption sites on the surface of a medium are occupied, the modified model is applied to unsteady-state operations of a biofilter so that the trends of the predictions may be comparable to those of the experimental data of Hodge and Devinny when granular activated carbon or compost are used as the medium of a biofilter. The characteristics of this model do not require a numerical solution but a simple analytical algebraic solution to express the concentration of an organic pollutant in waste air streams even under unsteady operating conditions. Thus the modified model would satisfy the important model requirement of simplicity and would be a unique model that is able to explain theoretically the effect of adsorption capacity of the medium to the pollutant removal efficiency of a biofilter.View full abstractDownload PDF (164K) -
MITSUO YAMAMOTO, SEIICHI ONA, SUGURU NODA, MASAYOSHI SADAKATA2001 Volume 34 Issue 6 Pages 834-839
Published: 2001
Released on J-STAGE: April 26, 2002
JOURNAL RESTRICTED ACCESSExhaust gas from a diesel engine is one of the main causes of air pollution. It is difficult to reduce NO under the excess O2 concentration so that effective method of NO reduction has not been developed. In this study, nickel on the porous glass (VYCOR® glass) was examined as a catalyst for NO reduction. This catalyst was effective for NO reduction where 35% of NO was converted to N2 under excess O2 concentration (3%) in the tubular fixed-bed reactor. Adsorption rates of NO and O2 gases were measured in order to examine the mechanism of selective reduction of NO by porous VYCOR catalyst. It was proved that NO adsorption rate was much higher than O2 adsorption rate, so that difference of adsorption rate was one of the main causes of NO reduction. As a short lifetime of the catalyst was the serious disadvantage of the tubular fixed-bed reactor, another type of catalytic reactor was proposed and tested. It is a membrane reactor consisting of a porous VYCOR catalyst tube and a quartz tube. NO reduction under excess O2 concentration was also achieved in the membrane reactor. Maximum conversion from NO to N2 was 45%. The possibility of longer lifetime catalyst could be found.View full abstractDownload PDF (78K)
- |<
- <
- 1
- >
- >|