Advanced Materials Research Vols. 512-515

Abstract: This study presents an energetic performance analysis for a waste heat produces electrical power system which is use organic Rankine cycle (ORC) from steelworks. In order to simulate the system under steady-state conditions, a mathematical model is developed. The developed model is used to determine the potential effects caused by the changes of the design parameters on the energetic performance of the system. As design parameters, turbine inlet pressure, condenser temperature, are taken into account. In this regard, the electrical power is estimated by parametrical analysis and discussed comprehensively.

Abstract: In this paper, a schematic of such installation is presented here with a description of its operation and the algorithm of calculations of a supercritical waste heat plant. An analysis of the influence of a kind of working fluid on the effectiveness of operation of a plant was carried out. The obtained results enabled the unanimous conclusion that the application of supercritical conditions in low-temperature organic Rankine cycle (ORC) installations of waste heat plants allows significantly higher values of both efficiency and power to be achieved.

Abstract: Grand Canonical Monte Carlo (GCMC) method is employed to simulate the adsorption of methane in several nanoporous zeolites. Adsorption isotherms over the temperature 177-398K and the pressure 0-12MPa are simulated. And their adsorption capacities of methane in these zeolites at different temperatures and pressures are also compared. The results show that: (1) the methane uptake is in the order of LTA>MOR>MFI at the same condition. The isosteric heat can support this conclusion: the value of isosteric heat in LTA is the largest, intermediate in MOR and the least in MFI. (2) The effects of the pore volume, channel size and the energetic interactions between zeolite and methane on adsorption amounts are considered. A large pore volume and a suitable channel size near to the kinetic diameter of a methane molecule are very important for improving the storage capacity of zeolites. Based on this, we conclude that LTA zeolite with a large pore volume and a suitable channel diameter exhibit a most efficient methane storage capacity than MOR and MFI zeolites.

Abstract: By changing influent COD volume loading and dyestuff volume loading of membrane bio-reactor, the anti-shock capacity of traditional MBR and bio-ferric MBR was analyzed comparatively. The experiment results showed: whatever the influent COD volume loading altered, the supernatant and effluent COD in bio-ferric MBR varied less than that in traditional MBR, and the discreteness was smaller which indicated that the reinforcement of bio-ferric sludge could enhance the system stability, and the anti-shock loading of bio-ferric MBR was much better than traditional MBR. While the influence of the influent dyestuff volume loading on dyestuff concentration in supernatant and dyestuff removal efficiency was smaller. The relationship between influent COD volume loading and dyestuff loading and removal volume loading were linear.

Abstract: There are several ongoing researchers on searching for an appropriate model to describe the characteristic of Vanadium redox flow batteries(VRB) .Based on one of these models, a SOC estimator of VRB- Extended Kalman Filter (EKF) is advanced. And then, update the VRB model by using EKF to estimate SOC when simulation in SIMULINK. At last, the effects of the temperature and operating current on performance of VRB, including battery capacity, output voltage, efficiencies are discussed.

Abstract: The dynamic model of the air supply system for a proton exchange membrane fuel cell (PEMFC) stack is developed in this paper. The PEMFC cathode/anode, and air supply system including a compressor, a motor, and a supply manifold(SM) are modeled; the compressor performance map is identified based on a fuzzy neural network (FNN). The PEMFC air supply system is simulated by using Matlab environment. The simulation results show that the proposed models can effectively represent the dynamic characteristics of the system components, and lay the foundation for the control strategy design of the PEMFC air supply flow.

Abstract: The proton exchange membrane fuel cell possesses the inherent benefit of low operating temperature, rapid start-up, and high power density, which makes it the ideal power source for electric vehicles. The fuel cell vehicle is envisioned as the vehicle of the future in response to environmental, economic and political constraints. Taiwan is one of the major producers and consumer of ICE-powered scooters in the world. The purpose of this field demonstration project is to prototype the fuel-cell-powered hybrid scooter both in performance and logistic support for mass adoption of this next generation commuting vehicle in Taiwan.

Abstract: Gas supply system in a proton exchange membrane fuel cell power system consists of hydrogen supply and oxygen supply. In order to improve the system output performance and maintain the pressure difference between the anode and cathode at the setting points under the variational load currents, a generalized predictive control strategy is applied to the gas supply system of a proton exchange membrane fuel cell in this paper. The fuel cell stack and gas supply system were modeled for the purpose of performance analysis and controller design. And then the designed generalized predictive controller was implemented to control the hydrogen flow rate and oxygen compressor voltage. The simulation results illustrated that the proposed controller can provide better response characteristics of the pressure difference, hydrogen and oxygen supply system as compared with PID controller.

Abstract: It was well known that the Mg₂Ni-type alloy with a nanocrystalline/amorphous structure possesses superior hydrogen storage kinetics. In order to obtain a nanocrystalline and amorphous structure, the melt spinning was applied to prepare the Mg₂Ni-type Mg₂₀Ni₆M₄ (M=Cu, Co) hydrogen storage alloys. The microstructures of the as-cast and spun alloys were characterized by XRD, SEM and HRTEM. The gaseous hydriding and dehydriding kinetics of the alloys was measured. The results show that the as-spun (M=Co) alloys display a nanocrystalline and amorphous structure as spinning rate approaches to 20 m/s, while the as-spun (M=Cu) alloys hold an entire nanocrystalline structure whatever spinning rate is, suggesting that the substitution of Co for Ni facilitates the glass formation in the Mg2Ni-type alloy. The melt spinning markedly improves the gaseous hydrogen storage kinetics of the alloys. As the spinning rate grows from 0 (as-cast was defined as the spinning rate of 0 m/s) to 30 m/s, the hydrogen absorption saturation ratio ( ) is enhanced from 57.7% to 91.4% for the (M=Cu) alloy and from 77.1% to 93.5% for the (M=Co) alloy. And hydrogen desorption ratio ( ) is raised from 28.7% to 59.0% for the (M=Cu) alloy and from 54.5% to 70.2% for the (M=Co) alloy, respectively.

Abstract: Hollow microspheres with less than 1 millimeter in diameter and several micrometers in wall thickness are attractive for hydrogen storage and transportation. The hollow microspheres can be made by drop tower technique, microencapsulation and vapor deposition methods. By immersion in high pressure hydrogen for a period of time at elevated temperature, the hollow microspheres can be filed with hydrogen gas at pressures up to one hundred MPa. The hydrogen mass fraction can be varied from 1% to 10% for hollow microspheres with different membrane hoop stress at failure.