Fusheng Yang

A Review on the Metal Hydride Based Hydrogen Purification and Separation Technology

With the expansion of application fields of the high purity hydrogen (hydrogen content>99.9999%), its preparation methods, in particular recovery from multi-component mixture,have attracted wide attentions. This paper describes the principle of hydrogen separation and purification process based on metal hydride, and some key issues involved in it, such as the alternatives of raw gas, the processing of hydride materials, the design of metal hydride reactor are discussed according to the literature reports. Finally, the current problems encountered in hydride based gas separation are presented, and future trends are also predicted.

Theoretical Investigation of Solar Energy High Temperature Heat Storage Technology Based on Metal Hydrides

A solar energy storage system based on metal hydrides was proposed in this paper. The numerical simulation of processes of energy storage and thermal release were carried out. The dynamic behavior of heat and mass transfer in the metal hydride energy system were reported. Some factors which influence the whole system performance were discussed. The paper also made an economic analysis of the system, the results proved that the large amounts of metal hydride materials and the configurations of metal hydrides energy storage system involve a critical situation from an economical point of view. Then further analysis, particularly regarding the performance optimization and new plant arrangement of the metal hydrides energy storage system, has to be developed in order to attain the economical feasibility of the proposal.

Microstructure and improved hydrogen storage properties of Mg based alloy powders prepared by modified milling method

Abstract In this study, the modified preparation method of combining planetary and vibratory ball milling was proposed to prepare Mg based hydrogen storage alloy powders. The comparison of micromorphology and hydrogen storage behaviour between Mg2Ni prepared using the modified and conventional preparation methods were investigated experimentally. The comparison results showed that the combination of first planetary and then vibratory ball milling has more favourable effect on improving both the kinetics and the thermodynamics of ball milled Mg2Ni alloys. The sample synthesised by first planetary milling for 40 h and then vibratory milling for 30 h has faster hydrogen absorption kinetics and lower dehydriding onset temperature than those prepared by the single method of planetary or vibratory milling and hydriding combustion synthesis owing to its popcorn-like microstructure. Moreover, this kind of modified method reduces the reaction enthalpy and activation energy by up to ∼18 and 22% respectively.

Simulation Studies on the Coupling Process of Heat/Mass Transfer in a Metal Hydride Reactor

Many substances can react with hydrogen under certain conditions, and the products are generally called hydrides. The binary hydrides can be classified into ionic hydrides, covalent hydrides and stable complex hydrides (Berube et al., 2007). The metal hydrides (MH), which feature metallic bonding between hydrogen and host material, belong to the second category and are investigated here. Since the successful development of LaNi5 and TiFe as hydrogen storage materials in 1970s, studies on the metal hydrides have attracted many attentions. According to (Sandrock & Bowman, 2003), two properties among all have been found crucial in MH applications: 1. The easily reversed gas-solid chemical reaction, which is expressed as follows,

Design Optimization of Autoswitch Hydrogen Absorption and Desorption Device Using Metal Hydrides

Abstract Metal hydride is an influential and promising material for hydrogen utilization. Researchers have carried out a large number of studies on hydrogen storage apparatus, and developed a few new devices for its promotion. Unfortunately, for most metal hydride reactors, the hydrogenation and dehydrogenation are two independent processes owing to the different required conditions, which could cause many inconveniences and safety problems to the H2 absorption & desorption cycle with high frequency and intensity. Hence we proposed a new type of autoswitch H2 absorption & desorption device based on the structure improvement, which consists of rotation disc, fixed disc and the reactor. The numerical simulation for H2 absorption/desorption using LaNi5 was accomplished, and the optimizations on both structure and operation conditions were achieved within a certain period of cycle time. Simulation results show when the single cycle time is set to 1600 s, the absorption temperature has to be lower than 45 °C (3 MPa) and pressure higher than 1.28 MPa (20 °C), and the desorption temperature should be higher than 41 °C (0.1 MPa) and pressure lower than 0.48 MPa (80 °C) under the same cycle time. Meanwhile, the effects of reaction finish time, operating temperature and H2 pressure during absorption/desorption process was investigated and simulation data were also fitted to develop the structural optimization. Under the hydrogenation/dehydrogenation conditions of 3 MPa (20 °C)/0.1 MPa (80 °C), the simulation results indicate the optimal initial reacted fraction and total cycle time are 0.07 and 1287 s, respectively. Moreover, both structures of autoswitch device with 4 and 6 openings have been optimized to satisfy the requirement of each stage. The autoswitch H2 absorption & desorption device can realize the automatic switch between hydrogenation and dehydrogenation orderly and controllably, which would provide convenience for the occasions with this demand and show its remarkable value during popularization and application.

Experimental Study on the Hydrogen Storage Properties of LaNi5 Alloy in Repeated Hydriding/Dehydriding Cycles

LaNi5 alloy is one of the promising materials for hydrogen storage. It has good activation property, fast reaction rate and moderate plateau pressure. However, some of its hydrogen storage properties will change after repeated hydriding/dehydriding cycles, which limits its practical application. Therefore, this paper investigated the cycling properties of LaNi5 alloy by volumetric method. The results showed that the reaction rate increased with cycling. The hydriding/dehydriding hydrogen content decreased with cycling. For hydriding reaction, the equilibrium pressure increased with cycling, while it decreased for dehydriding at 40°C and 60°C. After 100 cycles, the LaNi5 alloy has been severely pulverized and oxygenated. The oxidation products include LaNiO2, La2NiO4, La2NiO4.18 and LaNiO3. The JMA model was found to fit the kinetic data well, suggesting a nucleation and growth controlling mechanism. The intrinsic reaction rate constant ka increases from 21.87 s-1to 24.81 s-1, while the activation energy decreases from the initial value of 19459 to 19373 J/mol after 100 cycles.

Experimental study on the local turbulence modulation in a horizontal particle laden flow with rigid fence

The turbulence modulation by the existence of disperse phases, e.g. solid particles or liquid droplets, has attracted wide attentions in recent years. In this investigation, particles of different properties were fed with tracers into the turbulent atmospheric boundary layer disturbed by a rigid fence, and the velocities of both phases were obtained by PIV/PTV methods respectively. From both ensemble average and instantaneous analysis, the presence of particles was found to attenuate the local turbulence around the fence and in the downstream. In this case, the induced sand dune erosion by the turbulence when installing the rigid fence is also expected to decrease. The influences of the particles follow the order: GH>GL>No.9. The Stokes number under the given conditions showed that all the particles under discussion should cause augmented dissipation of turbulence. Moreover, through analyzing the relative velocities between the two phases, the cross-trajectory effect was found to be another possible mecha...

Teaching Reform Practice in the Background of Education Internationalization: An Example

Nowadays internationalization has been thought of as an important tendency in engineering education. The teaching practice for a certain course, therefore, should also adapt to the needs for talents development within such a background. Recently, following the education internationalization concept, the authors performed a systematic teaching reform on a course for postgraduates majoring in chemical engineering, including update and improvement on syllabus, contents, teaching methods as well as outcome assessment. In this paper we presented our thoughts and specific practice, in hope of being beneficial to other higher education practioners.

The Application of SOM Network to Particle Tracking Velocimetry in a Wind-Blown Sand Flow

Wind-blown sand flow is the basic phenomena that have profound influences on the environment, and the experimental study on the velocity distribution of the sand particles is very important for the understanding of this phenomena. Among the various experimental techniques, particle tracking velocimetry (PTV for short) is one that attracts more and more attentions. In this paper, an algorithm based on the Self-Organizing Maps network is established for PTV in a wind-blown sand flow, and the processing results by the algorithm prove its ability to capture the characteristics of the concerning flow field.

Performance Comparison and Analysis of Typical Energy Conversion Cycle

The performance of 3 types of energy utilization cycles including the organic Rankine cycle, the single stage static hydrogen compression cycle, and the new multistage continuous hydrogen compression cycle were analyzed. Amulti-element valued model was used to evaluate the performance holistically, and the result showed that the integrated superiority achieved 0.721, which indicated the continuous hydrogen compression cycle is considered the best option among the typical compression energy utilization cycles and deserves thorough studying.