JOURNAL OF CHEMICAL ENGINEERING OF JAPAN
Print ISSN : 0021-9592
Volume 47 , Issue 7
Showing 1-20 articles out of 20 articles from the selected issue
Editorial Note
  • 2014 Volume 47 Issue 7 Pages edit_7
    Published: July 20, 2014
    Released: July 20, 2014
    JOURNALS FREE ACCESS
    Editor-in-Chief
    Takao Tsukada (Tohoku University)

    Associate (Editor-in-Cheifs)
    Manabu Shimada (Hiroshima University)
    Masahiro Shishido (Yamagata University)

    Editors
    Ryuichi Egashira (Tokyo Institute of Technology)
    Jun Fukai (Kyushu University)
    Choji Fukuhara (Shizuoka University)
    Toshitaka Funazukuri (Chuo University)
    Takayuki Hirai (Osaka University)
    Jun-ichi Horiuchi (Kitami Institute of Technology)
    Eiji Iritani (Nagoya University)
    Yoshinori Itaya (Gifu University)
    Noriho Kamiya (Kyushu University)
    In-Beum Lee (Pohang University of Science and Technology (POSTEC))
    Kouji Maeda (University of Hyogo)
    Hideyuki Matsumoto (Tokyo Institute of Technology)
    Nobuyoshi Nakagawa (Gunma University)
    Masaru Noda (Fukuoka University)
    Hiroyasu Ogino (Osaka Prefecture University)
    Mitsuhiro Ohta (The University of Tokushima)
    Eika W. Qian (Tokyo University of Agriculture and Technology)
    Yuji Sakai (Kogakuin University)
    Noriaki Sano (Kyoto University)
    Naomi Shibasaki-Kitakawa (Tohoku University)
    Ken-Ichiro Sotowa (The University of Tokushima)
    Hiroshi Suzuki (Kobe University)
    Nobuhide Takahashi (Shinshu University)
    Shigeki Takishima (Hiroshima University)
    Yoshifumi Tsuge (Kyushu University)
    Tomoya Tsuji (Nihon University)
    Da-Ming Wang (National Taiwan University)
    Takuji Yamamoto (University of Hyogo)
    Yoshiyuki Yamashita (Tokyo University of Agriculture and Technology)
    Miki Yoshimune (National Institute of Advanced Industrial Science and Technology (AIST))

    Editorial office:
    The Society of Chemical Engineers, Japan
    Kyoritsu Building, 4-6-19, Kohinata, Bunkyo-ku
    Tokyo 112-0006, Japan
    journal@scej.org

    AIMS AND SCOPE:

    Journal of Chemical Engineering of Japan, an official publication of the Society of Chemical Engineers, Japan, is dedicated to providing timely original research results in the broad field of chemical engineering ranging from fundamental principles to practical applications. Subject areas of this journal are listed below. Research works presented in the journal are considered to have significant and lasting value in chemical engineering.

    Physical Properties and Physical Chemistry
    Transport Phenomena and Fluid Engineering
    Particle Engineering
    Separation Engineering
    Thermal Engineering
    Chemical Reaction Engineering
    Process Systems Engineering and Safety
    Biochemical Food and Medical Engineering
    Micro and Nano Systems
    Materials Engineering and Interfacial Phenomena
    Energy
    Environment
    Engineering Education
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  • Nobuyoshi Nakagawa, Takao Tsukada
    Type: Editorial Note
    2014 Volume 47 Issue 7 Pages 495-496
    Published: July 20, 2014
    Released: July 20, 2014
    JOURNALS FREE ACCESS
    Outstanding Paper Awards Subcommittee of Journal of Chemical Engineering of Japan has assessed the 116 papers published in volume 46 into 2013, and the editorial board finally selected the five papers for JCEJ Outstanding Paper Awards of 2013; those are the papers on “Radiation Properties of Coal Char Particle Cloud,” “Evaluation of a Self-Heat Recuperative Thermal Process Based on Thermodynamic Irreversibility and Exergy,” “Micropore Filling Phase Permeation of a Condensable Vapor in Silica Membranes: A Molecular Dynamics Study,” “A Front-Tracking Method for Three-Phase Computations of Solidification with Volume Change,” and “Development of New Hybrid VOCs Treatment Process Using Activated Carbon and Electrically Heated Alumite Catalyst.”
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Special Issue for the International Symposium on Innovative Materials for Processes in Energy Systems 2013 (IMPRES2013)
  • Type: Preface
    2014 Volume 47 Issue 7 Pages 497
    Published: July 20, 2014
    Released: July 20, 2014
    JOURNALS FREE ACCESS
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  • Michihisa Koyama, Seiichiro Kimura, Yasunori Kikuchi, Takao Nakagaki, ...
    Type: Journal Review
    2014 Volume 47 Issue 7 Pages 499-513
    Published: July 20, 2014
    Released: July 20, 2014
    [Advance publication] Released: June 26, 2014
    JOURNALS FREE ACCESS
    It has been an important target to realize a sustainable energy usage in the future, regardless of the country. Japan is now compelled to consider a new paradigm of energy policy due to the nuclear power plant failures after March 11, 2011. To discuss the ideal or a favorable future of Japan’s energy, understanding the present status as well as the available energy options in the future will be an initial step, followed by discussion of the issues related to each option. The aim of this article is to summarize the present status of Japan’s energy systems and to clarify the major points of discussions for the realization of future sustainable energy systems. In addition, the major options of both energy supply and demand sides are summarized. The issues for realizing the future energy systems are discussed from the large-scale penetration of renewable systems, the demand side energy management and savings, the mobility, and the centralized electricity grid viewpoints, to provide a common basis for the discussion of future energy systems in Japan.
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  • Iori Shimada, Yoshito Oshima, Junichiro Otomo
    Type: Research Paper
    2014 Volume 47 Issue 7 Pages 514-520
    Published: July 20, 2014
    Released: July 20, 2014
    [Advance publication] Released: June 26, 2014
    JOURNALS OPEN ACCESS
    To evaluate the availability of non-Pt catalysts in a direct ethanol fuel cell operating at an intermediate temperature, a PdRu/C catalyst was synthesized by a liquid phase reduction method and its catalytic activity for ethanol electro-oxidation was investigated at approximately 250°C using a single cell fabricated with CsH2PO4 proton-conducting solid electrolyte. Electrochemical measurement and reaction product analysis revealed that direct electro-oxidation of ethanol and hydrogen production from ethanol proceeded in parallel on PdRu/C. The PdRu/C catalyst showed high activity for hydrogen production reaction comparable to that on the PtRu/C catalyst, which results in high current density at low electrode potentials (<200 mV). C–C bond dissociation proceeded rapidly on the PdRu/C catalyst, while the subsequent oxidation of the adsorbed C1 species may be the rate-determining step at the intermediate temperature. For further activation of the PdRu/C catalyst, activation of surface OH should be investigated.
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  • Akira Nishimura, Kazuhiro Iio, Masashi Baba, Taisuke Yamauchi, Masafum ...
    Type: Research Paper
    2014 Volume 47 Issue 7 Pages 521-529
    Published: July 20, 2014
    Released: July 20, 2014
    [Advance publication] Released: June 26, 2014
    JOURNALS RESTRICTED ACCESS
    The aim of this study is to construct a simple heat-transfer model to present the temperature of the interface between the polymer electrolyte membrane (PEM) and the catalyst layer at the cathode, i.e., the reaction surface, in a single cell of polymer electrolyte fuel cell (PEFC). The model is based on the temperature data of the separator measured by thermograph in a power-generation experiment. In addition, this study also aims to investigate the effect of the operation condition on the temperature of the reaction surface using the heat-transfer model developed. The heat-transfer model is constructed by assuming multi plate heat transfer for components of a single cell of PEFC. In this model, the temperature of the reaction surface under the rib of separator and that under the gas channel of the separator are assumed to be the same. The result shows that the temperature of the reaction surface is higher with increasing gas channel pitch. The impact of the flow rate of the supply gas on the temperature of the reaction surface is small when O2 is used as the cathode supply gas. When air is used as the cathode supply gas, the temperature of the reaction surface is higher than that when O2 is used. The temperature of the reaction surface at the inlet is lower than that at the middle and outlet of the cell. This study can explain these temperature characteristics under several conditions by power-generation performance and energy conversion of the fuel cell.
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  • Ryuji Kikuchi, Misato Yokoyama, Shohei Tada, Atsushi Takagaki, Takashi ...
    Type: Research Paper
    2014 Volume 47 Issue 7 Pages 530-535
    Published: July 20, 2014
    Released: July 20, 2014
    [Advance publication] Released: June 26, 2014
    JOURNALS OPEN ACCESS
    Novel nickel catalysts based on magnesium aluminate spinel-type mixed oxides are developed as hydrocarbon reforming catalysts for hydrogen supply to polymer electrolyte fuel cells. The spinel catalysts were prepared by co-precipitation and the Pechini method, and the spinels prepared by the former method exhibited higher activity for methane steam reforming. The effect of spinel composition, Mg1−xNixAl2O4 (x=0.17, 0.35, 0.50, 0.70, 1) was investigated on the activity and resistance to carbon deposition in steam reforming reaction. The turnover frequency for methane steam reforming at a steam-to-carbon (S/C) ratio of 2 increased with increase in the x value from 0.17 to 0.35, and then gradually decreased with further increase in the nickel content. The carbon deposition tolerance of the spinel catalysts was examined in propane steam reforming at S/C=1 and 600°C. The propane conversion during the reaction was ca. 98% over all catalysts tested, and the amount of deposited carbon, determined as carbon dioxide by temperature programmed oxidation, was least at x=0.17, which is 1/8 of that deposited on a conventional Ni/γ-Al2O3 catalyst. The spinels with x≤0.5 exhibited smaller amounts of carbon deposition, and thus superior tolerance to deactivation.
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  • Chihiro Okuno, Lu Zhou, Yu Guo, Lu Jia, Makoto Sakurai, Hideo Kameyama
    Type: Research Paper
    2014 Volume 47 Issue 7 Pages 536-541
    Published: July 20, 2014
    Released: July 20, 2014
    [Advance publication] Released: June 26, 2014
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    A metal-monolithic anodic alumina supported nickel catalyst with an interfacial NiAl2O4 layer was prepared to investigate its performance in the steam reforming of methane (SRM). Compared with commercial catalysts, this catalyst showed excellent SRM durability at 700°C. This is believed to result from the presence of the interfacial NiAl2O4 layer, which could anchor the top metallic Ni particles, and thus effectively suppress oxidation and sintering of Ni. The nickel reduced from the interfacial NiAl2O4 layer was found to be vital for SRM durability. By varying the preparation conditions of calcination temperature and impregnation sequence, a catalyst with an optimum interfacial NiAl2O4 layer was obtained. The catalyst morphologies in this study are also examined.
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  • Mitsuhiro Kubota, Keiichi Matsuo, Ryo Yamanouchi, Hitoki Matsuda
    Type: Research Paper
    2014 Volume 47 Issue 7 Pages 542-548
    Published: July 20, 2014
    Released: July 20, 2014
    [Advance publication] Released: June 26, 2014
    JOURNALS RESTRICTED ACCESS
    Ammonia has attracted great attention as a hydrogen carrier owing to its high hydrogen content of 17.8 wt%. However, a high pressure of approximately 1 MPa is required to store NH3 in its liquid state at room temperature. The toxicity of ammonia has raised a great deal of concern about leakage from the storage vessel to the ambient atmosphere. To solve this problem, we have focused on absorption and desorption reactions of ammonia with metal chlorides. Some metal chlorides can store NH3 in the form of a stable chemical substance even at room temperature and low NH3 concentrations. Moreover, metal ammine complexes decompose into metal chlorides and ammonia by heating at relatively low temperatures below 473 K. In this study, the reaction characteristics of MeCl2·lNH3 (Me=Mn, Ni, Mg, Sr, and Ca) complexes were investigated by using a thermogravimetric analyzer. A detailed study was carried out on the NH3 absorption/desorption reactions using MnCl2 and NiCl2 because of their considerably high NH3 absorption capacity and fast reaction rates. A rate expression was determined as a function of the reaction temperature and NH3 pressure for the reaction-controlled period. It was also demonstrated that the reactivity of the metal chlorides was maintained after ten cycles of absorption and desorption.
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  • Sou Hosokai, Koichi Matsuoka, Koji Kuramoto, Satoru Matsuda, Yoshizo S ...
    Type: Research Paper
    2014 Volume 47 Issue 7 Pages 549-554
    Published: July 20, 2014
    Released: July 20, 2014
    [Advance publication] Released: June 26, 2014
    JOURNALS RESTRICTED ACCESS
    An in situ bio-oil upgrading process employing two circulating fluidized beds (CFBs) in series is proposed. One CFB allows the rapid pyrolysis of biomass and the other CFB facilitates bio-oil upgrading in the presence of a catalyst. In bio-oil upgrading CFBs, bio-oil is deoxygenated with hydrogen which is known as the hydrodeoxygenation (HDO) process. A system analysis was carried out on this process with respect to heat and mass balance to optimize the process efficiency and operating conditions. The product distribution of the pyrolysis CFB was experimentally obtained using a fluidized-bed reactor. According to the experimental results, a pyrolysis temperature of 823 K produced the highest bio-oil yield of 66 mass%. Based on the analysis of the bio-oil upgrading process, the maximum energy conversion from biomass to bio-oil was determined to be as high as 70% with respect to the biomass lower heating value (LHV). The energy conversion was strongly affected by the amount of hydrogen that was introduced to the bio-oil upgrading CFB. The bio-oil upgrading CFB produced a large amount of heat owing to the exothermic reaction of the HDO process. Heat elimination from the bio-oil upgrading CFB was required to maintain the catalyst temperature. It was found that the thermal utilization of unreacted hydrogen and an increased bio-oil yield during pyrolysis are required to further improve the energy conversion.
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  • Yugo Osaka, Kohei Yamada, Takuya Tsujiguchi, Akio Kodama, Hongyu Huang ...
    Type: Research Paper
    2014 Volume 47 Issue 7 Pages 555-560
    Published: July 20, 2014
    Released: July 20, 2014
    [Advance publication] Released: June 26, 2014
    JOURNALS RESTRICTED ACCESS
    The removal of sulfur dioxide (SO2) contained in the combustion exhaust gas from medium-scale facilities is necessary because of its role as an air pollutant. In this study, we focus on dry DeSOx filters that use simple desulfurization materials to capture SO2; in particular, we used manganese dioxide (MnO2) that takes part in the sulfation (MnO2+SO2→MnSO4). We determined the reactivity of high-surface-area MnO2 (HSSA MnO2) with SO2 using thermogravimetry. We obtained the desulfurization rate for a sample of MnO2 that was wash-coated on a monolith. The MnO2 sample, having a specific surface area of 250 m2/g, absorbed 0.43–0.45 gSO2/gMnO2. Under this experimental condition, the conversion of the sulfation was dependent on the amount of the supported MnO2. The absorption efficiency of these samples was more than 90.0%. Based on our results, we estimated that 20 m3 of absorbent was required to capture the exhaust gas of an ocean ship with a crossing time of 20 d, operating at 8,500 kW power at 450°C.
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  • Takahiro Tanaka, Eiki Tabata, Takao Nakagaki, Mamoru Mizunuma, Yasuko ...
    Type: Research Paper
    2014 Volume 47 Issue 7 Pages 561-568
    Published: July 20, 2014
    Released: July 20, 2014
    [Advance publication] Released: June 27, 2014
    JOURNALS RESTRICTED ACCESS
    Lithium ortho-silicate (Li4SiO4) is a suitable solid sorbent for capturing CO2 from solid oxide fuel cells. CO2 absorption reactors packed with porous-solid spherical pellets of Li4SiO4 show unsteady temperature distribution and capture ratio behavior owing to the unsteady CO2 absorption rate and highly exothermic process. The CO2 absorption rate of this sorbent reportedly depends on temperature, CO2 concentration, and CO2 accumulation, expressed as the weight change of the sorbent. Nevertheless, discussions of detailed mechanisms of CO2 absorption by this sorbent are rare. In this study, the modified unreacted core model is proposed to explain the mechanism of CO2 absorption of a porous-solid spherical pellet, and numerical analysis was conducted to simulate the unsteady behavior of the sorbent. Important properties such as the reaction rate constant, the gas film mass transfer coefficient, and the coefficient for effective diffusion through the product layers were empirically derived using thermogravimetry and a diluted packed-bed reactor. Numerical analysis by applying these parameters to the modified unreacted core model adequately explained the complicated CO2 absorption and regeneration behaviors.
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  • Mikihiro Nomura, Emi Matsuyama, Ayumi Ikeda, Makoto Komatsuzaki, Misa ...
    Type: Research Paper
    2014 Volume 47 Issue 7 Pages 569-573
    Published: July 20, 2014
    Released: July 20, 2014
    [Advance publication] Released: June 27, 2014
    JOURNALS RESTRICTED ACCESS
    CO2 separation through membranes represents a solution for efficient CO2 recovery. A high temperature CO2 permselective membrane can be applied to a membrane reactor for reforming reactions. However, CO2 permselective membranes have been primarily developed as low temperature polymeric membranes. Only a few articles have reported high temperature CO2 permselective membranes. We prepared silica membranes using chemical vapor deposition (CVD) for high temperature hydrocarbon separation. In this study, the pore size control of the silica membranes was investigated. CVD was performed at 150–450°C for 90 min. Propyltrimethoxysilane (PrTMOS) was used as the silica source. PrTMOS and O3 were provided from opposite sides of the porous alumina substrate. The CO2/N2 permeance ratio was the highest (20) using the membrane deposited at 270°C. The deposition conditions were investigated using FT-IR measurements of the PrTMOS hydrolysis powder. Absorption at 2,960 cm−1 indicated C–CH3 stretching. The ratio of the absorption at 2,960 cm−1 of the as-made sample and the calcined sample was evaluated. This ratio was the maximum (0.41) with treatment at 270°C. Thus, the CO2 permselectivity is likely due to the remaining alkyl groups on the membrane. The activation energy of CO2 permeation was negative, while that of N2 was 5.6 kJ mol−1. The negative activation energy indicates that the permeation is due to adsorption on the membrane.
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  • Ayumi Ikeda, Emi Matsuyama, Makoto Komatsuzaki, Misa Sasaki, Mikihiro ...
    Type: Research Paper
    2014 Volume 47 Issue 7 Pages 574-578
    Published: July 20, 2014
    Released: July 20, 2014
    [Advance publication] Released: June 27, 2014
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    Silica hybrid membranes have been developed for use as reverse osmosis (RO) membranes by using a counter-diffusion chemical vapor deposition (CVD) method. A silica source (phenyltrimethoxysilane; PhTMOS) and O3 were provided at opposite sides of a porous alumina substrate at 300°C for 90 min. The RO permeation test was conducted for 100 mg L−1 NaCl at 3.0 MPa. The highest NaCl rejection was 94.2% for a total flux of 1.7 kg m−2 h−1. The module length is an important factor in obtaining highly selective RO membranes. The short module (6 cm) was better because of the higher O3 concentration in the module. The decomposition conditions of phenyl groups on the silica surface are discussed for the hydrolysis powder of PhTMOS. According to FT-IR measurements, phenyl groups remained on the silica surface after O3 treatment for 90 min at 300°C, whereas the number of silanol groups decreased by approximately 30% upon O3 treatment at 300°C. The high Na+ rejection can be explained by the reduction of the silanol groups in the membrane.
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  • Junichi Ryu, Takafumi Mizuno, Hirokazu Ishitobi, Yukitaka Kato
    Type: Research Paper
    2014 Volume 47 Issue 7 Pages 579-586
    Published: July 20, 2014
    Released: July 20, 2014
    [Advance publication] Released: June 27, 2014
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    The dehydration and hydration behaviors of Mg–Co mixed hydroxides and the effect of LiCl addition were studied to develop a new material for chemical heat storage. The formation of the mixed hydroxides and LiCl addition were expected to reduce the dehydration temperature of authentic magnesium hydroxide; this temperature corresponds to that of heat-storage operation. That the dehydration temperature of Mg–Co mixed hydroxides was found to be approximately 280°C, which was lower than that of authentic magnesium hydroxide. The mixed hydroxides showed higher hydration reactivities than authentic magnesium oxide at 110°C with 57.8 kPa of water vapor after dehydration at 300°C. The dehydration temperatures of Mg–Co mixed hydroxides were lowered by LiCl addition. LiCl-added Mg–Co mixed hydroxides showed higher hydration reactivities than the usual Mg–Co mixed oxides after dehydration at 250°C. The heat-output performance of LiCl/Mg0.95Co0.05(OH)2 was estimated as 715 kJ kg−1 after dehydration at 250°C. These results indicated that Mg–Co mixed hydroxides can be used to utilize industrial waste heat between 250°C and 300°C.
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  • Hongxia Zhang, Hironao Ogura
    Type: Research Paper
    2014 Volume 47 Issue 7 Pages 587-594
    Published: July 20, 2014
    Released: July 20, 2014
    [Advance publication] Released: June 27, 2014
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    From the viewpoints of energy and environmental problems in the world, the development of effective energy utilization technologies such as chemical heat storage/pump and their practical uses are required. In this paper, the hydration reaction rates of various size CaO particles for calcium oxide/water chemical heat storage/pump were studied using thermogravimetric analysis based on the grain model. Firstly, we calculate a reaction rate equation using the coefficient ηr for the particle size effects as model I, which is based on our previous method for calcium sulfate considering the effects of the particle size. Furthermore, the catalyst effectiveness factor taking into account the mass transfer resistance within the porous particles, the particle expansion and the pore size changes along with the hydration reaction is proposed and introduced into a new reaction model II, because the shapes of the calculated data in model I and the experimental data are different. As a result, it is demonstrated that the intraparticle mass transfer resistance increases as the particle size increases. Further, the proposed applied grain model I enables evaluation of this experiment roughly. Furthermore, the applied grain catalyst model II shows that the calculated conversion lines are consistent with the experimental data for 106–1,000 µmϕ particles considering the pressure drop inside the particles by the introduction of the catalyst effectiveness factor. In addition, the expansion ratio of the CaO particles is lower than that of the grains in the reaction model II.
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  • Odtsetseg Myagmarjav, Junichi Ryu, Yukitaka Kato
    Type: Research Paper
    2014 Volume 47 Issue 7 Pages 595-601
    Published: July 20, 2014
    Released: July 20, 2014
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    A new candidate for a chemical heat storage material used in a magnesium oxide–water chemical heat pump at medium- temperature (200–300°C) was developed. The new composite, named EML, was fabricated by mixing pure magnesium hydroxide (Mg(OH)2) with lithium bromide (LiBr) and expanded graphite, which are employed as reactivity and heat transfer enhancers, respectively. The effects of mixing mole ratios of LiBr-to-Mg(OH)2, α, on both dehydration and hydration were kinetically investigated by a thermogravimetric method. It was experimentally demonstrated that the reacted mole fractions of dehydration and hydration increased with increasing α value. Further, the activation energy, Ea, of the dehydration process was significantly reduced for the EML with high α. Therefore, it was concluded that the Ea values determined here are dependent on α. Further, the EML composite showed cyclic ability with repeat reactions over five cycles. Thus, this composite can be used as a chemical heat storage material because of its ability to store heat at medium-temperatures ranging from 220 to 300°C.
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  • Yuji Suwa, Mikio Kumita, Hiroaki Komori, Akio Kodama, Yoshio Otani
    Type: Research Paper
    2014 Volume 47 Issue 7 Pages 602-607
    Published: July 20, 2014
    Released: July 20, 2014
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    In the present study, a calcium chloride-oxalic acid anodized alumina composite was proposed as a sorbent of water vapor for the application to adsorption chiller. CaCl2-anodic alumina composite sorbents were prepared by anodic oxidation of an aluminum plate in an oxalic acid bath, following the widening of pores in anodic oxide films with a sulfuric acid solution and the impregnation of saturated aqueous solution of CaCl2 into the pores at a reduced pressure. As a result, the alumina films prepared in an oxalic acid bath had numerous large pores, and their porosities were significantly larger than those of sulfuric acid-anodized alumina films. The amounts of CaCl2 impregnated into the alumina films were a function of the apparent densities of the films, and the maximum CaCl2 content was 39.7 wt%. The CaCl2-anodic alumina composites were capable of sorbing water vapor even in the relative pressure range below 0.3. With higher doses of CaCl2 contained by the alumina film, a larger amount of water vapor was sorbed by the composite. Furthermore, the CaCl2-oxalic acid anodized alumina composite showed a fast water sorption rate like commercial silica-gel particles.
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  • Takuya Tsujiguchi, Yugo Osaka, Akio Kodama
    Type: Research Paper
    2014 Volume 47 Issue 7 Pages 608-614
    Published: July 20, 2014
    Released: July 20, 2014
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    The effect of designing conditions, such as the length and the ratio of the adsorption area of the desiccant wheel, and the operation conditions, such as the volumetric flow rate and air velocity, on the volume of the desiccant wheel were estimated using numerical analysis in order to present an operation and designing concept which can minimize the size of the desiccant wheel. As example results, it was found that a 40% reduction in the volume of the desiccant wheel was expected comparing to that of a typical commercialized one when 8 g/kg of dehumidified water was obtained by selecting the appropriate operating/designing parameters. Moreover, when the volumetric flow rate of adsorption air and the regeneration air were the same at 500 m3/h, it was found that a 32% reduction in volume of desiccant wheel was expected comparing to that of a typical commercialized one when 8 g/kg of dehumidified water was obtained by operating it at appropriate conditions. These results suggested that a desiccant wheel can be miniaturized by selecting appropriate designing and operating parameters.
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  • Tomoe Yayama, Yoshihiro Kangawa, Koichi Kakimoto
    Type: Research Paper
    2014 Volume 47 Issue 7 Pages 615-619
    Published: July 20, 2014
    Released: July 20, 2014
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    This study theoretically investigates the influence of the growth orientation on In incorporation during metal-organic vapor phase epitaxy (MOVPE) growth. We propose a new theoretical model based on first-principles calculations that show the role of the N–H molecular layer on In incorporation. Under MOVPE growth conditions, III-nitride surfaces terminated by N–H molecular layers are stable. The N–H layer that covers the In atomic layer prevents In atom desorption and is replaced by Ga atoms. In incorporation is, therefore, more efficient for higher N–H layer coverage and stability. To investigate this relationship, calculation of the enthalpy change for the decomposition of an N–H molecular layer was performed. To take into account the experimental conditions, temperature dependence of surface reconstruction is considered. The trend of this enthalpy change depends on the growth orientation, which agrees well with the experimental In composition.
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