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Teruhisa Horita, Haruo Kishimoto, Katsuhiko Yamaji, Yue-Ping Xiong, Na ...
Article type: Research Paper
2007 Volume 40 Issue 13 Pages
1172-1177
Published: December 27, 2007
Released on J-STAGE: December 27, 2007
Advance online publication: October 10, 2007
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The chemical stability of Fe–Cr alloys (ZMG232 and SUS430) was examined in fuel atmosphere of SOFC, especially in H
2–H
2O atmosphere. Oxide scales were formed on the alloy surface with a thickness of 3–5 μm at 1073 K for 1000 h by the diffusion of cations through the scale. The microstructures and elemental distribution of oxide scale/alloy interfaces were analyzed by the depth and surface analysis techniques: Mn–Cr–(Fe) spinel, Cr
2O
3, and internal Si oxides were identified from surface to inner oxides. An anomalous thick oxide scale formation was found on SUS430 surface in H
2–H
2O atmospheres. A thick oxide scale was composed of Fe, Cr, and Mn oxides. A relatively high concentration of Fe was observed at top surface of oxide scale. The distribution of Si was found inside the oxide scale, suggesting an increase of oxygen potential and fast diffusion of Si inside the oxides. The formation of anomalous thick oxide scale can affect the stability of Fe–Cr alloy interconnects by changing the cell connections at scale/alloy/cell interfaces.
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Haruo Kishimoto, Yue-Ping Xiong, Katsuhiko Yamaji, Teruhisa Horita, Na ...
Article type: Research Paper
2007 Volume 40 Issue 13 Pages
1178-1182
Published: December 27, 2007
Released on J-STAGE: December 27, 2007
Advance online publication: October 10, 2007
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Direct feeding of several hydrocarbon fuels was carried out at 800°C for a SOFC with scandia stabilized zirconia (ScSZ) electrolyte and nickel–ScSZ (Ni–ScSZ) cermet anode. Liquid hydrocarbons as
n-dodecane (paraffin type C
12H
26) and low sulfur content kerosene were used and fed to the anode at steam/carbon ratio (S/C) of 2. Continuous operation was achieved for more than 120 h with
n-dodecane without anode degradation. However, the Ni–ScSZ anode completely detached from the electrolyte when low sulfur kerosene was used as fuel. After operation with the kerosene, nickel particles grew more than 3 μm in diameter although particle growth was about 1 μm under the
n-dodecane. The nickel sintering seems to be enhanced by aromatic hydrocarbons and/or sulfur compounds in the kerosene. From thermodynamic consideration, liquid NiS could form under SOFC operation conditions with 30 ppm of sulfur containing hydrocarbon fuels.
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Hiroshi Fukunaga, Yoshimi Numazawa, Akinori Fueoka, Chikao Arai, Toru ...
Article type: Research Paper
2007 Volume 40 Issue 13 Pages
1183-1186
Published: December 27, 2007
Released on J-STAGE: December 27, 2007
Advance online publication: October 10, 2007
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A Pd doped perovskite La
0.85Sr
0.15Cr
0.9Ni
0.05Pd
0.05O
3 (LSCNP) was investigated as a candidate for a metal-free anode material of solid oxide fuel cell in comparison with La
0.85Sr
0.15Cr
0.9Ni
0.1O
3 (LSCN). The performance of anodes of LSCNP and LSCN with and without mixing Sm doped Ceria (SDC) was measured using H
2 and dry-CH
4 as fuel. The maximum current density of the cell in H
2 increased approximately twofold by the doping of Pd for the anode with or without SDC. The rate of the anodic reaction in H
2 was enhanced mainly by the catalytic activity of LSCNP and additionally by SDC. When dry-CH
4 was used as the fuel, the cell with LSCNP-SDC anode was the only cell which was able to perform power generation. Both the doping of Pd to the perovskite and the mixing of SDC contributed to the ability to operate SOFC in dry CH
4. The anode reaction did not occur when SDC was not in the anode, indicating that the supply of oxide ion was the rate determining step. Pd, which is considered to deposit from LSCNP in reducing atmosphere, seemed to be the reaction site of the electrochemical methane oxidation since the reaction rate was low for LSCN-SDC. Although slight indication of carbon deposition was observed, Pd doped perovskite would be a good candidate for metal-free SOFC anode.
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Tamara Kharlamova, Svetlana Pavlova, Vladislav Sadykov, Olga Lapina, D ...
Article type: Research Paper
2007 Volume 40 Issue 13 Pages
1187-1191
Published: December 27, 2007
Released on J-STAGE: December 27, 2007
Advance online publication: October 10, 2007
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Al- and Sr-doped apatite-type lanthanum silicates (ATLS) have been prepared using mechanochemical activation (MA) and Pechini (Pe) methods. MA of a stoichiometric mixture in the high-power planetary ball mill provides the formation of a high purity crystalline ATLS at room temperature after 20–35 min activation. The phase composition and local structure of doped ATLS are determined by milling time and the dopant content. 5 min MA of carbonate precursors obtained via Pe method results in the formation of a single-phase ATLS at 900°C.
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Nobuhide Takahashi, Hidenori Kagamifuchi, Akifusa Hagiwara, Koichi Yam ...
Article type: Research Paper
2007 Volume 40 Issue 13 Pages
1192-1198
Published: December 27, 2007
Released on J-STAGE: December 27, 2007
Advance online publication: October 10, 2007
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A simulation model has been developed for the analysis of heat, flow and mass transfer coupled with the electrochemical reactions and current collection of a solid oxide fuel cell (SOFC) located in a double-tube type testing device. The simulation model was used to examine the influence of the current collection conditions and gas flow rates on the temperature and concentration fields in the device, and on the resulting cell performance. The results indicated that the high flow rate of air induced a great temperature gradient near the cell surface. It was also pointed out that the low flow rate of fuel significantly lowered the cell performance through the concentration field, especially when the flow channel for fuel gas was not enough long. The mathematical simulation of the phenomena occurring in the testing device as well as at the cell can be a strong measure for precise interpretation of the experimental results and the development of SOFCs.
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Nobuyoshi Nakagawa, Mohammad Ali Abdelkareem
Article type: Research Paper
2007 Volume 40 Issue 13 Pages
1199-1204
Published: December 27, 2007
Released on J-STAGE: December 27, 2007
Advance online publication: October 10, 2007
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The effect of CO
2 discharge from the CO
2 gas layer formed between the anode surface and a porous carbon plate, PCP, was investigated to in order to clarify the role of the PCP and the CO
2 gas layer on the performance and mass transfer in a passive DMFC using different types of PCPs with different pore structures. The relation between the gas discharge through or not through the PCP and the DMFC performance as well as the effect of the gas pressure in the layer were investigated using PCPs with a small pore size, i.e., 1 μm average diameter, PCPS, and that with a large pore size, a 42 μm average diameter, PCPY. The formation of the CO
2 gas layer was essential for significantly limiting the methanol transport to the anode surface where the gaseous methanol diluted in the CO
2 gas contacted with it. The resistance of the methanol transport across the PCP was affected by the pore structure of the PCP, i.e., the pore size and the bubble point pressure. The discharging of bubbles through the large pore size PCP of 42 μm accelerated the methanol transport through the PCP in contrast to the small diameter PCP.
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Tomohiro Nozaki, Kei Hayashi, Tsuyoshi Kajitani
Article type: Research Paper
2007 Volume 40 Issue 13 Pages
1205-1209
Published: December 27, 2007
Released on J-STAGE: December 27, 2007
Advance online publication: October 10, 2007
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We have studied crystal structure and high temperature thermoelectric properties of delafossite-type oxide CuFe
1–xNi
xO
2 (0 ≤
x ≤ 0.05). There is no significant difference in the lattice parameter
a among the Ni-doped samples and CuFeO
2 due to the decrease of Fe–O distance and simultaneous increase of O–Fe–O angle by the Ni doping. The lattice parameter
c is slightly longer in the doped samples than that of CuFeO
2, reflecting the increase of Cu–O distance. The decrease of the Fe–O distance indicates hole doping in the Fe-site. Because of the hole doping, the electrical conductivity
σ is enhanced to 18 S/cm. The Seebeck coefficient
S decreases slightly by the Ni doping, but remains high (
S > 250 μV/K). The obtained Seebeck coefficient at high temperature agrees well with theoretical values based on the generalized Heikes formula that takes the spin entropy flux into account. The thermal conductivity
κ of CuFe
1–xNi
xO
2 is relatively high (
κ > 4 W/mK). The maximum
ZT value,
ZT =
σS2T/
κ = 0.14 is obtained with the sample of
x = 0.01 at 1100 K.
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Hiroyuki Nakagawa, Akio Namba, Atul Sharma, Kouichi Miura
Article type: Research Paper
2007 Volume 40 Issue 13 Pages
1210-1215
Published: December 27, 2007
Released on J-STAGE: December 27, 2007
Advance online publication: October 10, 2007
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Treatments of wastewaters containing various organic compounds in small concentrations are causing serious problems elsewhere in the world, therefore, the development of efficient process for treating wastewaters has been desired. In this study a novel Ni-supported carbon catalyst that we developed was used for gasifying the organic compounds dissolving in an industrial wastewater under hydrothermal conditions. The organic compounds were almost completely gasified above 275°C under the conditions examined. Main gaseous products were CH
4, H
2, and CO
2, having the lower heating value of around 20 MJ/m
3, indicating that the product gas can be used as fuel gas. The product gas composition was highly dependent on pressure: H
2 and CO
2 were dominant components under 5 MPa, and CH
4 and CO
2 were dominant ones under 20 MPa when the wastewater was gasified at 300°C. Equilibrium calculation for the reactions clarified that these results reflected the state of water, vapor or liquid, in the reactor. A simple calculation for mass and energy balance of the proposed process showed that 46% of the lower heating value of the organic compound (aqueous isopropyl alcohol solution of 3.33 wt% in concentration) can be recovered as fuel gas under the conditions of
Tg = 350°C,
P = 20 MPa even when this process is operated as a stand-alone one. This result shows that the proposed process can be not only a wastewater treatment process but an energy production process if certain conditions were met.
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Yoshinori Saito, Nobuyuki Wada, Yukio Sakabe
Article type: Research Paper
2007 Volume 40 Issue 13 Pages
1216-1220
Published: December 27, 2007
Released on J-STAGE: December 27, 2007
Advance online publication: October 10, 2007
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We tested the use of Ba
2TiO
4 to remove CO
2 from steam reforming gas of CH
4 and thereby increase the concentration of H
2 in the gas. The results of passing reforming gas through a reactor filled with a CO
2 absorbent based on Li
4SiO
4 ceramics at 600 to 700°C demonstrated that the concentrations of CO
2 and CO were reduced, while the H
2 concentration was increased to about 95%, by the progression of the water shift reaction. At a temperature of 650°C or less, or a space velocity of 250 h
–1 or less, the use of a shift reactor might not be necessary after the reforming because the CO concentration was less than 2000 ppm.
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Yu Guo, Thanh Phong Tran, Lu Zhou, Qi Zhang, Hideo Kameyama
Article type: Research Paper
2007 Volume 40 Issue 13 Pages
1221-1228
Published: December 27, 2007
Released on J-STAGE: December 27, 2007
Advance online publication: October 10, 2007
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A plate-type metal-monolithic anodic alumina supported nickel catalyst (Ni/Al
2O
3/Alloy) was employed to investigate the reactivity and the catalyst deactivation in the SMR reaction, and several methods of activation treatments were proposed. After H
2 reduction, a fresh Ni/Al
2O
3/Alloy catalyst only provided a short-term SMR activity, and then quickly deactivated. The oxidation of metallic nickel with steam into oxidation state was believed to be the most serious reason for the catalyst deactivation. After the second H
2 reduction, a deactivated catalyst (or a catalyst with the treatments of H
2 reduction and subsequent air oxidation) was observed to provide a more favorable SMR stability, compared a reduced fresh catalyst.
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Thanh Phong Tran, Yu Guo, Lu Zhou, Hideo Kameyama
Article type: Research Paper
2007 Volume 40 Issue 13 Pages
1229-1234
Published: December 27, 2007
Released on J-STAGE: December 27, 2007
Advance online publication: October 10, 2007
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To improve the heat resistance of the conventional alumite catalyst, a commercial Al/Fe–Cr–Alloy/Al clad base material was used to prepare a plate-type clad alumite support with high resistance.
The pre-heat treatment of the base material at 773 K for 3 h or longer has a significant inhibitory on the alumina layer shelling off, due to the formation of the interfacial alloy diffusion layer. The pore widening treatment at 293 K for 8 h provided an excellent alumite support that was enough strong to suffer the high temperature of 1273 K without the alumina layer shelling off. No alumina layer was found to shell from the alloy layer after 5000 times’ repeat electrically heating shock test. Though the BET surface area was decreased with increasing the calcination temperature, the application of this EAHC catalyst at high temperature is still considered to be a promising area at least at 1073 K.
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Mikihiro Nomura, Toshihiro Nagayo, Keita Monma
Article type: Research Paper
2007 Volume 40 Issue 13 Pages
1235-1241
Published: December 27, 2007
Released on J-STAGE: December 27, 2007
Advance online publication: October 10, 2007
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A molecular sieve silica membrane was successfully prepared by using a counter diffusion chemical vapor deposition method. Effects of silica precursors on permeation properties through the silica membranes were investigated. Five types of silica alkoxides (tetramethyorthosilicate (TMOS), methyltrimethoxysilane (MTMOS), trimethylmethoxysilane (TMMOS), propyltrimethoxysilane (PrTMOS) and phenyltrimethoxysilane (PhTMOS)) were employed for the silica precursors. H
2, N
2 and SF
6 permeances were measured through the silica membranes at 300°C. H
2 permselective silica membranes were obtained from the smaller silica precursors such as TMOS, MTMOS or TMMOS. H
2/N
2 permecnces ratios were over 200, while N
2/SF
6 permeances ratios were around 1. According to the kinetic diameters of H
2 (0.26 nm), N
2 (0.36 nm) and SF
6 (0.55 nm), pore sizes of the membranes were about 0.3 nm. N
2 permselective silica membrane was obtained from the larger silica precursors such as PrTMOS or PhTMOS. N
2/SF
6 permeances ratios through the membranes prepared by PrTMOS or PhTMOS were 30 and 32, respectively. Those values are much larger than that of Knudsen diffusion (2.3). H
2/N
2 permeances ratios through the membranes were about 40 showing that the maximum pore sizes are around 0.5 nm. These results show that the pore size of silica membranes can be controlled by changing the silica precursors. The PhTMOS membrane was confirmed as a silica membrane without carbon remaining by the cross-sectional XPS measurements.
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Yury I. Aristov
Article type: Journal Review
2007 Volume 40 Issue 13 Pages
1242-1251
Published: December 27, 2007
Released on J-STAGE: December 27, 2007
Advance online publication: October 10, 2007
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The brief review of innovative materials for adsorptive pumping and storage of low temperature heat as well as current trends in this field showed their great potential. To implement it in the near future it is reasonable to follow two complementary lines: (a) systematic testing for this application novel adsorbents initially developed for other targets (gas drying, separation, etc.), and (b) tailoring of new specific porous materials adapted just to variety of adsorptive cooling, heating and storage cycles under different climatic and boundary conditions. The main idea of the latter approach is that for each particular adsorptive cycle there is an optimal adsorbent, the thermodynamic characteristics of which could allow perfect performance of this cycle. The first step of the analysis is the formulation of requirements to this desirable (ideal) adsorbent. Then, the final step is to design and synthesize a new adsorbent with sorption properties close or even equal to those determined before as perfectly fitting the cycle. Particular examples of nanotailoring of adsorption properties are given for two phase materials, composites “a salt in a porous host matrix”, which can be used as efficient adsorbents of water, methanol and ammonia.
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Hironao Ogura, Masahiro Haguro, Yasuhiro Shibata, Yasufumi Otsubo
Article type: Research Paper
2007 Volume 40 Issue 13 Pages
1252-1256
Published: December 27, 2007
Released on J-STAGE: December 27, 2007
Advance online publication: October 10, 2007
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We had proposed chemical heat pumps using a reversible calcium sulphate/water reaction system for effective waste energy utilization. However, more reaction kinetics studies are necessary for this reaction system, especially for different atmosphere condition and different materials. As a result, the reaction equilibrium line of CaSO
4 in the closed system like CHP system was found to be close to that in the open system. It means that the CHP using CaSO
4/CaSO
4·1/2H
2O reversible reaction stores under 373 K level thermal energy, and releases the same level hot heat and 273 K level cold heat. Furthermore, the effects of material size on the reaction rates could be calculated by the proposed equations, which enable the effective CHP reactor design.
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Koichi Nakaso, Ryosuke Shigenaga, Jun Fukai
Article type: Research Paper
2007 Volume 40 Issue 13 Pages
1257-1263
Published: December 27, 2007
Released on J-STAGE: December 27, 2007
Advance online publication: October 10, 2007
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Metal hydride (MH) attracts considerable attention for not only hydrogen storage devices but also chemical heat pumps (CHPs). Many previous researchers pointed out low effective thermal conductivity of MH packed bed resulted in low performance. Indeed, several attempts have been done to improve it. However, no guideline for improving the thermal performance with heat transfer enhancement has been discussed. In this study, thermal performance for a packed bed reactor of MH is numerically investigated. Diagrams for the heat transfer enhancement are developed according to the numerical results. The previous strategies to improve effective thermal conductivity can be combined with the diagrams for the practical use.
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Yukitaka Kato, Tomofumi Saito, Tsutomu Soga, Junichi Ryu, Yoshio Yoshi ...
Article type: Research Paper
2007 Volume 40 Issue 13 Pages
1264-1269
Published: December 27, 2007
Released on J-STAGE: December 27, 2007
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Durable reaction material for repetitive reaction operation of a chemical heat pump that used a reversible magnesium oxide/water reaction system was discussed to enhance the heat pump performance. Because a material for the heat pump use was required to fit multi-production process, a molding method was introduced for material preparation. Some molded samples under different preparation conditions were evaluated kinetically by a thermo-balance analysis. Magnesium hydroxide prepared from ultra fine particle magnesium oxide and purified water showed enough reactivity, and also stable durability to 70 of repetitive reaction cycles. Removal of impurity was effective for durability enhancement of magnesium hydroxide made from seawater precipitated precursor. The cost of the precipitated hydroxide was less than one several tenths of the ultra fine particle material. It was demonstrated that the molded reactant made from precipitated hydroxide was applicable for multi production and cost reduction of magnesium hydroxide material for the heat pump. The thermal performance of magnesium oxide/water chemical heat pump was evaluated from experimental results.
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Masahiko Aihara, Keiko Tanaka, Mayuka Watanabe, Takashi Takeuchi, Hito ...
Article type: Research Paper
2007 Volume 40 Issue 13 Pages
1270-1274
Published: December 27, 2007
Released on J-STAGE: December 27, 2007
Advance online publication: October 10, 2007
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The carbonation and decarbonation of the Ca solid reactant prepared by the natural limestone powder were analyzed about the effect of annealing temperature on the reactivity and the durability in repetitive operation. The solid reactants annealed at 1073 K and lower had the larger reproducible pore volume in the range from 10 to 25 nm, and showed the higher conversion of carbonation. The solid reactants annealed at 1273 K indicated the excellent durability of repetitive cyclic procedure, which was comparable to that of the reactant prepared by the metal alkoxide method.
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Peng Zhang, Cheng Wang, Ruzhu Wang
Article type: Research Paper
2007 Volume 40 Issue 13 Pages
1275-1280
Published: December 27, 2007
Released on J-STAGE: December 27, 2007
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A new process for fabricating composite reactive block composed of the expanded graphite and reactive salt for the heat transformer system is proposed. The suitable condition to expand the graphite is found to be over 700°C for 15 min, and the reactive salt is impregnated by immersing the expanded graphite in the reactive salt solution. The performance of the heat transformer using the composite reactive block is accordingly simulated. It is found that the gas volume has quite important effect on the matching of the reacting rates and consequently it affects the system performance. The system
COP is higher in the case of small gas volume, in particular when the driven temperature is high.
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Junichi Ryu, Rui Takahashi, Naoya Hirao, Yukitaka Kato
Article type: Research Paper
2007 Volume 40 Issue 13 Pages
1281-1286
Published: December 27, 2007
Released on J-STAGE: December 27, 2007
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The mixing effect of transition metal ion into magnesium hydroxide on dehydration and hydration reactivity was studied to develop a new material for chemical heat-storage, because the mixing effect was expected to reduce dehydration-temperature, corresponding to heat-storage temperature, of authentic magnesium hydroxide. Two-components composite materials mixed with some content of nickel ion or cobalt ion into magnesium hydroxide were tested, respectively. It was demonstrated that the dehydration-temperatures of the composites were shifted to lower temperature below 300°C with increase of nickel or cobalt content in comparison with dehydration-temperature of authentic magnesium oxide of 350°C. These composites showed higher hydration reactivity than that for authentic magnesium oxide under the same reaction condition, and were expected to be applicable to heat utilization of middle-temperature waste heat less than 300°C.
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Larisa G. Gordeeva, Angelo Freni, Giovanni Restuccia, Yuri I. Aristov
Article type: Research Paper
2007 Volume 40 Issue 13 Pages
1287-1291
Published: December 27, 2007
Released on J-STAGE: December 27, 2007
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The performance of an adsorptive air-conditioning cycle driven by low temperature heat (80–85°C) was studied. The analysis rested on the Polanyi potential theory and took into account literature and author’s experimental data on sorption equilibrium of various conventional and innovative adsorbents with water and methanol as working fluids. This adsorbent screening is aimed at evaluating the optimal working pairs for this application. The composite sorbent of methanol Lithium Chloride in mesoporous silica gel and the adsorbent of water FAM-Z02 were selected as challenging pairs for severe conditions of heat rejection typical for solar cooling in hot countries and air conditioning in cars.
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Hitoshi Asano, Takehiko Nakajima, Nobuyuki Takenaka
Article type: Research Paper
2007 Volume 40 Issue 13 Pages
1292-1297
Published: December 27, 2007
Released on J-STAGE: December 27, 2007
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Evaluation of hygroscopic water distribution in adsorber is important to design adsorption refrigerating system, because the adsorption and desorption process strongly affect on the cycle performance. A neutron radiography method was applied to a diagnosis of a silica-gel adsorber, such as nondestructive testing of the structure of particle layer and real-time measurement of hygroscopic water distributions. Silica gel particles of diameter around 0.5 mm were used. The attenuation coefficient of neutron beam for the silica gel particle layer was measured using a sample rectangular capsule. Then, a silica-gel unit was made by filling the silica-gel particles between fins on the outside of an aluminum cylinder. The particles were fixed with vinyl acetate glue. The internal structure of the unit was successfully visualized with the spatial resolution of 107 μm. From the visualized images, 3-D structure of the unit was clearly obtained by a computed tomography method. From the comparison between dry and wet condition, hygroscopic water distribution could be measured. Moreover, radial distribution could be obtained by Abel transform assuming the axial symmetry.
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Belal Dawoud
Article type: Research Paper
2007 Volume 40 Issue 13 Pages
1298-1306
Published: December 27, 2007
Released on J-STAGE: December 27, 2007
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The kinetics of water vapor adsorption/desorption under quasi isobaric conditions have been studied on one layer of loose pellets of FAM-Z02 placed on a metal plate. Temperature of the sample holding plate has been changed as it takes place in real adsorption heat pumps (AHPs), while the vapor pressure over the adsorbent was maintained almost constant (saturation pressures corresponding to an evaporator temperature of 5°C and a condenser temperature of 35°C). Adsorption- and desorption-end temperatures have been adjusted to 35 and 90°C, respectively. Measurements have been carried out on grains having the following size distributions: 0.7 to 1.0 mm, 1.4 to 1.6 mm and 2.0 to 2.6 mm. An average equilibrium differential water loading of 19.2 g/100 g has been measured during desorption compared to 16.4 g/100 g during adsorption. The adsorption/desorption rates have been characterized by the times required to reach 50, 80 and 90% of the equilibrium loading. It has been found that the adsorption kinetics are mainly dominated by inter-crystalline diffusion, while the desorption kinetics are mostly influenced by surface resistance to the heat and mass transfer. Average specific evaporator cooling/condenser heating capacities in the order of 1 kW/kg have been estimated for the grain size 0.7 to 1.0 mm, putting in evidence the possibility of developing highly compacted AHPs with FAM-Z02 for heating and cooling applications. The influencing parameters on the combined heat and mass transfer process have been discussed.
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Lucio Bonaccorsi, Edoardo Proverbio, Angelo Freni, Giovanni Restuccia
Article type: Research Paper
2007 Volume 40 Issue 13 Pages
1307-1312
Published: December 27, 2007
Released on J-STAGE: December 27, 2007
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In this paper, the preparation of an adsorbent bed for adsorption heat pumps obtained by depositing zeolites on metal foam structures is discussed. Zeolites, the active adsorbent phase, were directly grown by
in situ synthesis on high surface area metal foams to improve heat and mass transfer in the adsorbent beds. Coatings of zeolite 4A on copper foams and of zeolite Y on aluminum foams were prepared and characterized by SEM, XRD analysis and measurement of the water equilibrium sorption curves by thermo-gravimetric method. The results, in terms of coatings thickness and zeolite characteristics, confirmed the chance for further developments of such zeolite-metal foam composites.
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Seiji Inoue, Satoshi Inoue, Noriyuki Kobayashi
Article type: Research Paper
2007 Volume 40 Issue 13 Pages
1313-1318
Published: December 27, 2007
Released on J-STAGE: December 27, 2007
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The adsorption refrigerator for automobiles reduces their environmental impact of automobiles, because it uses waste heat from the engine as its energy source. However, due to high ambient temperature of automobiles, the adsorbent for the adsorption refrigerator should have special characteristics to work in such high temperature conditions. In this study, the appropriate characteristics of adsorbent for the adsorption refrigerator for automobiles was estimated and some related results were obtained as follow. In high ambient temperature conditions, the relative humidity in adsorption stage will be smaller than that in desorption stage. Therefore the adsorption isotherm should have temperature dependency. The temperature dependency of adsorbent will be estimated from the Clausius–Clapeyron’s equation, and the
P/
Ps region according to the value of Δ
H is clarified in high temperature conditions of automobiles.
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Manabu Nakagawasai, Shigeaki Inada, Hisanobu Kawashima, Shigeki Matsuo ...
Article type: Research Paper
2007 Volume 40 Issue 13 Pages
1319-1327
Published: December 27, 2007
Released on J-STAGE: December 27, 2007
Advance online publication: October 10, 2007
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The purpose of this study is to adhere titanium, sodium and silver to the surface of woody biomass by low temperature plasma irradiation. As the woody biomass, wood powder and coffee grounds were used. First, those powder samples were ozonized by oxygen plasma irradiation. Next, TiCl
4 gas, NaNH
2 gas or AgNO
3 gas plasma was generated in a quartz tube and the sample was irradiated in the tube. The composition of the sample surface was identified using an XPS. In the result, it was confirmed that three kinds of metals bonded to the wood powder. The hydrophilic property, photocatalyst, and sterilization characteristic of the wood powder were examined.
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Tomoya Takenaga, Kei Hayashi, Tsuyoshi Kajitani
Article type: Research Paper
2007 Volume 40 Issue 13 Pages
1328-1329
Published: December 27, 2007
Released on J-STAGE: December 27, 2007
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We have measured the electrical resistivity of full Heusler Ni
2Mn
2–xSn
x (0.52 ≤
x ≤ 0.6) by a Van der Pauw method to determine a first-order structural transition temperature,
MS, and a second-order magnetic transition temperature,
TC.
MS and
TC are respectively decreasing and increasing linearly with the increasing Sn content
x. Although the
MS and
TC become closer, two phase transitions, i.e., the magnetic and martensitic phase transitions, do not undergo simultaneously in the range of 0.52 ≤
x ≤ 0.6.
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Satomi Shimooka, Kazunori Oshima, Hideto Hidaka, Takahiko Takewaki, Hi ...
Article type: Research Paper
2007 Volume 40 Issue 13 Pages
1330-1334
Published: December 27, 2007
Released on J-STAGE: December 27, 2007
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The paper focuses on development of new adsorbent material of aluminophosphate (FAM-Z05) which could be subsequently used in utilization of waste heat below 373 K. To evaluate this new material, water vapor adsorption isotherms of FAM-Z05 were measured at several temperatures. Furthermore, an attempt was made to improve the heat exchanger by coating FAM materials onto fin tube type heat exchanger. Then, the dehumidification performance of direct cooling and heating desiccant system was evaluated.
It was found that the water vapor adsorption isotherms of FAM-Z05 were characterized by S-shape and the adsorption character of FAM-Z05 was dependent on temperature. Further, the new adsorbent of FAM-Z05 was able to adsorb water vapor in lower regeneration temperature than FAMZ02 and FAM-Z01, which was attributed to FAM-Z05 ability to adsorb water vapor in high humidity range. However, when FAM-Z05 is used in low humidity range, the dehumidification performance of FAM-Z05 might be lower than those of FAM-Z01 and FAM-Z02.
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