Advanced Materials Research Vols. 347-353

Abstract: An experiment of a single direct methanol fuel cell (DMFC) was conducted at Fuel Cell laboratory of Tsinghua University, China in collaboration with University of Tsukuba, Japan. Influences of the anodic methanol solution's concentration, the cathodic air flow rate, and the cathodic oxygen gas flow rate on the single DMFC performance were investigated to optimize operating conditions of the fuel cell. The experimental results have shown that the single DMFC can reach the peak power density of 0.170 W/cm2 with the current of 0.515 A/cm2 under the condition of the concentration of methanol solution of 2M and the flow rate of oxygen gas of 80 mL/min.

Abstract: Liquid-liquid circulating fluidized bed(LLCFB), which is a novel method of dynamic ice-making, was studied using direct contact heat transfer between droplets and the coolant. In the paper the key problems on droplets formation in LLCFB were investigated by the high resolution digital camera and image processing, the photos of drop formation were obtained. The effects of the shape of jet breakup, jet length on the size and uniformity of drops were revealed. The characteristic of particles size distribution was also presented.

Abstract: Gaskets play important role in fuel stack assembly. It influences the assembly stress distribution or causes the risk of fuel leakage. The purpose of this paper is to study the assembly stress on the gasket and the MEA and the gasket development inside a stack of fuel cells. 2D and 3D models are established to explore the ideal behaviour of the couple MEA/gasket. A method is developed to define gasket shape parameters taking the MEA stress restrictions in consideration. Using PEMFC prototype, finite element simulations, pressure film experiments and joint integrity calculation code, an improvement on gasket section shape is performed to decrease the risk of fuel leakages. The design guideline and the analysis method proposed in this study will be helpful for the stack design to obtain high performance.

Abstract: A series of Pd catalysts supported on different materials (SiO2, γ-Al2O3, CeO2, TiO2) were synthesized through precipitation reduction of palladium ions with H2. They exhibited different activity during catalytic oxidation of CO to CO2. With the characterization of N2 physisorption experiment, X-ray diffraction, transmission electron microscopy, temperature-programmed reduction, and CO and O2 multi-pulse experiment, the correlation of catalytic activity and oxygen storage capacity (OSC) of catalyst has been investigated. It was found that the reactivity is largely controlled by the OSC of the catalysts, and thus Pd/CeO2 and Pd/TiO2 were more active than Pd/SiO2 and Pd/Al2O3 for CO oxidation.

Abstract: Abstract. The core-shell composite of platinum/polyaniline (Pt@PAN) had been prepared by chemical synthesis approach. Reduction of the platinum salt in aqueous solution leaded to the formation of platinum nanoparticles, and then polyaniline were synthesized by interfacial polymerization to get Pt@PAN composite. Transmission electron microscopy of Pt@PAN showed Pt particles are uniform with spherical and granular morphology. Pt@PAN was also characterized by EDAX, XPS and FTIR.

Abstract: The scopes of this research were to investigate efficiency of anaerobic digestion system to treat wastewater from air dried rubber sheet production process and to produce and use biogas from this system. Wastewater from air dried rubber sheet production process contains high organic substance and pH about 4.6. Therefore, this wastewater must be adjusted pH to be 7 before feeding to system in start-up period. Two tanks system (The system consisted of 2 digestion tanks, each tank was operated at HRT 7.5 days, total HRT was 15 days) provided higher wastewater treatment efficiency than one tank system (The system consisted of 1 digestion tank, it was operated at HRT 15 days). In this research, full-scale reactor (two tank system, total volume was 800 liters) was set up and operated at agriculturist’s home in Nakorn Sri Thamaraj, Thailand. From the first day to the fifteenth day of operating period, wastewater was adjusted pH from 4.6 to be 7.0 before feeding into reactor. After that, reactor was fed with wastewater which was not adjusted pH (pH about 4.6). The results of full-scale shown that this system provided average removal efficiency of COD, BOD, TSS, TKN and TP about 69.23%, 66.86%, 63.16%, 35.81% and 36.74%, respectively. Biogas production rate of full-scale system was 0.45 m3-gas/m3-reactor.day (0.57 m3-gas/kg CODremoved). Total biogas from full-scale reactor (800 liters) was 360 liters per day; it can be used for cooking about 2 hours per day. Compositions of biogas were methane 65%, carbon dioxide 32% and another gas such as nitrogen and hydrogen sulfide 3%.

Abstract: Solid oxide fuel cell (SOFC) is one of most promising types of fuel cells with advantages of high efficiencies, flexibility of usable fuel types. The performance of SOFC is strongly affected by cell overall parameters, e.g., temperature, pressure, reaction rates, etc. But it is very difficult to validate internal parameters distributions and complex physical processes by experimental method. The CFD model simulation has been proved an effective method for SOFC research. In this work, a 3D CFD model is developed to simulate the working processes in SOFC’s anode. The objective of this work is to study the effects of the parameters such as temperature, permeability, pores radius and elementary surface reaction rate on the working processes, by coupling the transport processes such as mass, momentum and thermal energy with the chemical reactions of gas- and surface-phase species based on catalyst surface coverage.

Abstract: Chemical hydrogen storage and release of iron-based oxide mediums were investigated by hydrogen reduction and water splitting oxidation (Fe3O4 + 4H2 ⇌ 3Fe + 4H2O). In this study, all metal oxide mediums were prepared by coprecipitation method using urea solution as precipitant. The redox reactions of the mediums were conducted using a fixed bed quartz reactor under atmospheric pressure. The theoretical amount of hydrogen storage that can be obtained from the redox reaction of iron oxide is calculated to be 4.8wt% on the basis of 1g-Fe. However, in case of using the iron oxide medium without additives, the medium was rapidly deactivated due to the agglomeration of Fe metals in the hydrogen reduction step of repeated redox cycles. In this study, therefore, Mo and Zr additives were added to iron oxide to improve the reactivity of the medium and to prevent the agglomeration of that. As a result, the reactivity for oxidation of the mediums was largely improved with the addition of Mo additive. It was concluded that change in the valence of Mo cations affected the redox behavior of the mediums.

Abstract: The work presents analyses of Crofer 22APU steel oxidation in hydrogen atmosphere containing 300 ppm H₂S and in hydrogen atmosphere containing 300 ppm and 1% H₂O. The oxidation process was conducted on two kinds of samples: pre-oxidized (pre-oxidation process was carried out in the air at a temperature of 800°C during 100 h), and not pre-oxidized at a temperature of 600 and 800°C using periodic method during 500 h. It was established that oxidation rate may be described by means of parabolic law. Determined parabolic rate constants indicate that not pre-oxidized samples undergo sulphurization in H₂/300ppm H₂S atmosphere, while in H₂/300ppm H₂S + 1%H₂O atmosphere they undergo oxidation 3-4 orders of magnitude slower.

Abstract: Ceramic systems of template explains and demonstrates how to prepare your camera-ready Ceramic systems of Bi2O3 and La-doped SrTiO3 (LST) solid mixtures La0.2Sr0.8TiO3–x%Bi2O3 (x = 0, 20, 25, 30, 35) are prepared and explored as possible anode materials for solid oxide fuel cells. It is shown that the conductivity of La0.2Sr0.8TiO3–x%Bi2O3 composites increases from 0.15 to 1.4 S cm−1 in 97%H2 +3%H2O at 800°C with increasing the content of Bi2O3. Electrochemical impedance spectra indicated that the addition of Bi2O3 into LST can significantly reduce the fuel cell’s polarization and refine the grains and increase the triple phase boundary, leading to a better performance of the fuel cells. The results suggest potential applications of LST–x%Bi2O3 composite as SOFC anode materials.