Optimal design considering structural efficiency of compressed natural gas fuel storage vessels for automobiles

The shape and thickness of the dome were investigated with the aim of optimizing the type II CNG storage vessels by using a finite element analysis technique. The thickness of the liners and reinforcing materials was optimized based on the requirement of the cylinder and dome parts. In addition, the shape of the dome, which is most suitable for type lI CNG storage vessels, was proposed by a process of review and analysis of various existing shapes, and the minimum thickness was established in this sequence： metal liners, composite materials and dome parts. Therefore, the new proposed shape products give a mass reduction of 4.8 kg（5.1%）

AB_5-type Hydrogen Storage Alloy Modified with Ti/Zr Used as Anodic Materials in Borohydride Fuel Cell

Fuel cell using borohydride as the fuel has received much attention. AB5-type hydrogen storage alloy used as the anodic material instead of noble metals has been investigated. In order to restrain the generation of hydrogen and enhance the utilization of borohydride, Ti/Zr metal powders has been added into the parent LmNi4.78Mn0.22 （where Lm is La-richened mischmetal） alloy （LNM） by ball milling and heat treatment methods. It is found that the addition of Ti/Zr metal powders lowers the electrochemical catalytic activity of the electrodes, at the same time, restrains the generation of hydrogen and enhances the utilization of the fuel. All the results show that the hydrogen generation rate or the utilization of the fuel is directly relative to the electrochemical catalytic activity or the discharge capability of the electrodes. The utilization of the fuel increases with discharge current density. It is very important to find a balance between the discharge capability and the utilization of the fuel.

Modeling of Large-Scale Hydrogen Storage System Considering Capacity Attenuation and Analysis of Its Efficiency Characteristics

In the existing power system with a large-scale hydrogen storage system,there are problems such as low efficiency of electric-hydrogen-electricity conversion and single modeling of the hydrogen storage system.In order to improve the hydrogen utilization rate of hydrogen storage system in the process of participating in the power grid operation,and speed up the process of electric-hydrogen-electricity conversion.This article provides a detailed introduction to the mathematical and electrical models of various components of the hydrogen storage unit,and also establishes a charging and discharging efficiency model that considers the temperature and internal gas partial pressure of the hydrogen storage unit.These models are of great significance for studying and optimizing gas storage technology.Through these models,the performance of gas storage units can be better understood and improved.These studies are very helpful for improving energy storage efficiency and sustainable development.The factors affecting the charge-discharge efficiency of hydrogen storage units are analyzed.By integrating the models of each unit and considering the capacity degradation of the hydrogen storage system,we can construct an efficiency model for a large hydrogen storage system and power conversion system.In addition,the simulation models of the hydrogen production system and hydrogen consumption system were established in MATLAB/Simulink.The accuracy and effectiveness of the simulation model were proved by comparing the output voltage variation curve of the simulation with the polarization curve of the typical hydrogen production system and hydrogen consumption system.The results show that the charge-discharge efficiency of the hydrogen storage unit increases with the increase of operating temperature,and H2 and O2 partial voltage have little influence on the charge-discharge efficiency.In the process of power conversion system converter rectification operation,its efficiency decreases with the increase of temperature,while in the process of inverter operation,power conversion system efficiency increases with the increase of temperature.Combined with the efficiency of each hydrogen storage unit and power conversion system converter,the upper limit of the capacity loss of different hydrogen storage units was set.The optimal charge-discharge efficiency of the hydrogen storage system was obtained by using the Cplex solver at 36.46%and 66.34%.

Numerical simulation of coupling heat transfer and thermal stress for spent fuel dry storage cask with different power distribution and tilt angles

Dry storage containers must be secured and reliable during long-term storage,and the effect of decay heat released from the internal spent fuel on the cask has become an important research topic.In this paper,a 3D computational fluid dynamics model is presented,and the accuracy of the calculation is verified,with computational errors of less than 6.2%.The thermal stress of the dry storage cask was estimated by coupling it with a transient temperature field.The total power remained constant and adjusting the power ratio of the inner and outer zones had a small effect on the stress results,with a maximum equivalent stress of approximately 5.2 kPa,which occurred at the lower edge of the shell.In the case of tilt,the temperature gradient varied in a wavy distribution,and the wave crest moved from right to left.Altering the tilt angle affects the air distribution in the annular gap,leading to the shell temperature being transformed,with a maximum equivalent stress of 202 MPa at the bottom of the shell.However,the equivalent stress in both cases was less than the yield stress(205 MPa).

Modeling and Simulation of Hydrogen Storage Device for Fuel Cell Plant

The article reviews a brief literature on the modeling of hydrogen storage device for fuel cell. Different dimensional approaches in modeling hydrogen absorption/desorption in a metal hydride reactor for use in fuel cell are summarized. Mathematical modeling equations involved are also stated. The effect of various operating parameters such as temperature, concentration, viscosity, thermal conductivity and time on the gas is also verified. The importance of various simulation software with reference to their major functions is also identified. The review concludes on the opportunities and challenges with the use of hydrogen as an alternative renewable energy.

Safe Controlled Storage of SVBR-100 Spent Nuclear Fuel in the Extended-Range Future

Experience of operating reactor facilities (RF) with lead-bismuth coolant (LBC) has revealed that it is possible to perform safe refueling in short terms if the whole core is replaced and a kit of the special refueling equipment is used. However, comparing with RFs of nuclear submarines (NS), in which at the moment of performance of refueling the residual heat release is small, at RF SVBR-100 in a month after the reactor has been shut down, at the moment of performance of refueling the residual heat release is about 500 kW. Therefore, it is required to place the spent removable unit (SRU) with spent fuel subassemblies (SFSA) into the temporal storage tank (TST) filled with liquid LBC, in which the conditions for coolant natural circulation (NC) and heat removal via the tank vessel to the water cooling system are provided. After the residual heat release has been lowered to the level allowing transportation of the TST with SRU in the transporting-package container (TPC), it is proposed to consider a variant of TPCs transportation to the special site. On that site after the SRU has been reloaded into the long storage tank (LST) filled with quickly solidifying liquid lead, the TPCs can be stored during the necessary period. Thus, the controlled storage of LSTs is realized during several decades untill the time when SNF reprocessing and NFC closing are becoming economically expedient. On that storage, the four safety barriers are formed on the way of the release of radioactive products into the environment, namely: fuel matrix, fuel element cladding, solid lead and steel casing of the LST.

Existing Condition Analysis of Dry Spent Fuel Storage Technology

As in some domestic nuclear power plants,spent fuel pools near capacity,away-from-reactor type storage should be arranged to transfer spent fuel before the pool capacity is full and the plants can operate in safety.This study compares the features of wet and dry storage technology,analyzes the actualities of foreign dry storage facilities and then introduces structural characteristics of some foreign dry storage cask.Finally,a glance will be cast on the failure of away-from-reactor storage facilities of Pressurized Water Reacto(rPWR)to meet the need of spent-fuel storage.Therefore,this study believes dry storage will be a feasible solution to the problem.

Seismic considerations for spent nuclear fuel storage in dry casks

To aid the United States Nuclear Regulatory Commission,Sandia National Laboratories (SNL) was contracted to investigate the seismic behavior of typical dry cask storage systems. Parametric evaluations characterized the sensitivity of calculated cask response characteristics to input parameters. The parametric evaluation investigated two generic cask designs (cylindrical and rectangular),three different foundation types (soft soil,hard soil,and rock),and three different casks to pad coefficients of friction (0.2,0.55,0.8) for earthquakes with peak ground accelerations of 0.25g,0.6g,1.0g and 1.25g. A total of 1 165 analyses were completed,with regression analyses being performed on the resulting cask response data to determine relationships relating the mean (16 % and 84 % confidence intervals on the mean) to peak ground acceleration,peak ground velocity,and pseudo-spectral acceleration at 1 Hz and 5 % damping. In general,the cylindrical casks experienced significantly larger responses in comparison to the rectangular cask. The cylindrical cask experienced larger top of cask displacements,larger cask rotations (rocking),and more occurrences of cask toppling (the rectangular cask never toppled over). The cylindrical cask was also susceptible to rolling once rocking had been initiated,a behavior not observed in the rectangular cask. Cask response was not overly sensitive to foundation type,but was significantly dependent on the response spectrum employed.

Plant Dynamics Evaluation of a MONJU Ex-vessel Fuel Storage System during a Station Blackout

The prototype fast breeder reactor ＂MONJU＂ has an EVSS （ex-vessel fuel storage system） which consists mainly of an EVST （ex-vessel fuel storage tank） and an EVST sodium cooling system. EVST sodium cooling system consists of three independent loops. During the normal operation, the primary sodium in the EVST is circulated by natural convection and the secondary circulation in the EVST sodium cooling system is powered by electromagnetic pumps. When an SBO （station blackout） occurs, all the pumps and blowers are tripped. Therefore, it was necessary to evaluate the cooling ability by the natural circulation of sodium in the EVST sodium cooling system and air through the air cooler during the SBO. In this study, an analysis and evaluation of the plant dynamics for the spent fuel and the EVSS structural integrity during an SBO were performed. When the number of cooling loops was not changed and natural circulation occurred in only two loops, the sodium temperature in the EVST increased to approximately 450 ~C. However, the structural integrity of the EVSS was maintained. The analytical results, therefore, help clarify the number of necessary cooling loops for efficient decay heat removal and sodium temperature behavior in an SBO.

Graphene oxide:An emerging electromaterial for energy storage and conversion

This paper gives a comprehensive review of the recent progress on electrochemical energy storage devices using graphene oxide(GO).GO,a single sheet of graphite oxide,is a functionalised graphene,carrying many oxygen-containing groups.This endows GO with various unique features for versatile applications in batteries,capacitors and fuel cells.Specific applications are considered principally including use in electrodes as the active materials to enhance the performance or as substrates to diversify the structures,in solid-state electrolytes and membranes to improve the ionic conductivity and mechanical properties,and in interlayers to protect the electrodes,membranes or current collectors.Furthermore,the challenges and future prospects are discussed in the paper for encouraging further research and development of GO applications.

Single-atom catalysts for electrochemical energy storage and conversion

The expedited consumption of fossil fuels has triggered broad interest in the fabrication of novel catalysts for electrochemical energy storage and conversion. Especially, single-atom catalysts(SACs) have attracted more attention owing to their high specific surface areas and abundant active centers. This review summarizes recent synthetic strategies to fabricate SACs with different metal loadings on various supports, and the structural influence of supports on metal loading. Then, the functions of SACs are illustrated on electronic structure and electrocatalysis;the isolated SACs with an unsaturated coordination environment generally accelerate the electrocatalytic process and promote the selectivity. The applications of SACs to some typical electrocatalytic reactions are also introduced in detail, as well as to electrochemical energy storage and conversion systems. Finally, the challenges and the perspectives of SACs are discussed for future exploration.

Biomass-Derived Materials for Electrochemical Energy Storage and Conversion: Overview and Perspectives

Electrochemical energy storage and conversion(EESC) technology is key to the sustainable development of human society. As an abundant and renewable source, biomass has recently shown widespread applications in EESC, achieving both low environmental impact and high performances. This article provides overview and perspectives on various types of biomassderived materials, their preparation, the role in EESC and the desired features, performances and limitations, and future research efforts.

Structural and hydrogen storage capacity evolution of Mg_2FeH_6 hydride synthesized by reactive mechanical alloying

Mg-based metal hydrides are promising as hydrogen storage materials for fuel ce ll application. In this work,Mg2FeH6 complex hydride phase was synthesized by controlled reactive ball milling of 2Mg-Fe （atomic ratio） powder mixture in H2. Mg2FeH6 is confirmed to be formed via the following three stages: form ation of MgH2 via the reaction of Mg with H2,incubation stage and formation of Mg2FeH6 by reaction of fully refined MgH2 and Fe. The incubation stage is characterized by no traces of Mg or hydride crystalline phase by XRD. On the other hand,Mg is observed uniformly distributed in the milled powder by SEM-E DS. Also,almost the same amount of H2 as the first stage is detected stored i n the powders of the second stage by DSC and TGA.

Energy Storage System with Ultracapacitors for Thermal Underwater Glider

A power system with proton exchange membrane fuel cells (PEMFC) was designed for thermal underwater glider.Heat generated by PEMFC is used as the propulsion power of the glider,and the electricity is used in the control and sensor system.An electric energy storage system (ESS) is required which possesses high power density with good cycle life.Ultracapacitors which exhibit high power density and cycle life are considered as energy storage devices.Simulations based on a specific voyage condition indicate that ESS with ultracapacitors has positive effects on reducing the output power demand of PEMFC and lightening the power system.Experimental results show that the state of charge (SOC) is related to the capacitance and resistance in ultracapacitor ESS.

Compact Electric Energy Storage for Marine Vehicles Using on-Board Hydrogen Production

The use of electric energy in marine vessels has been increasing in recent years. In general, it is motivated by the low ecological impact. However, in the case of underwater vehicles it is functionally essential. The objective of this study is to demonstrate the advantage of electric power generation and storage based on on-board hydrogen generation via the reaction between activated aluminum and water and application of the hydrogen in a fuel cell. The original activation process enabling a spontaneous reaction with water to produce hydrogen as well as a parametric study of hydrogen generation rate and yield are briefly described. The potential increase in specific energy （energy per unit mass） and energy density （energy per unit volume） vs. batteries and other means of hydrogen storage is presented. It is shown that the use of the present technology may result in a substantial increase of specific electric energy along with a reduction in volume or an increase in operating time for the same overall mass of energy storage and generation system.

Electrochemical properties of AB_5 type hydrogen storage alloy as anode electrocatalyst of PEMFC

The electrocatalytic properties of hydrogen storage alloy（HSA） MlNi3.65Co0.85Al0.3Mn0.3 substituting Pt as anode electrocatalyst of PEMFC was investigated. It is found that, after being optimized, the electrocatalytic abilities of the HSA is reasonably good, the current density of the HSA anode membrane and electrode assembly（MEA） reaches 168 mA/cm2 at 0.5 V and 232.4 mA/cm2 at 0.2 V, and its power density reaches the maximum value of 84 mW/cm2. The influence of operating temperature and hydrogen pressure on the electrocatalytic behavior of HSA anode MEA is also discussed. At 60 ℃ under 2.02×105 Pa H2, the HSA anode shows the best electrochemical properties.

Recent progress on mechanisms,principles,and strategies for high-activity and high-stability non-PGM fuel cell catalyst design

The commercialization of a polymer membrane H2-O2 fuel cell and its widespread use call for the development of cost-effective oxygen reduction reaction(ORR)nonplatinum group metal(NPGM)catalysts.Nevertheless,to meet the requests for the real-world fuel cell application and replacing platinum catalysts,it still needs to address some challenges for NPGM catalysts regarding the sluggish ORR kinetics in the cathode and their poor durability in acidic environment.In response to these issues,numerous efforts have been made to study NPGM catalysts both theoretically and experimentally,developed these into the atomically dispersed coordinated metal-nitrogen-carbon(M-N-C)form over the past decades.In this review,we present a comprehensive summary of recent advancements on NPGM catalysts with high activity and durability.Catalyst design strategies in terms of optimizing active-site density and enhancing catalyst stability against demetalization and carbon corrosion are highlighted.It is also emphasized the importance of understanding the mechanisms and principles behind those strategies through a combination of theoretical modeling and experimental work.Especially,further understanding the mechanisms related to the active-site structure and the formation process of the single-atom active site under pyrolysis conditions is critical for active-site engineering.Optimizing the active-site distance is the basic principle for improving catalyst activity through increasing the catalyst active-site density.Theoretical studies for the catalyst deactivation mechanism and modeling stable active-site structures provide both mechanisms and principles to improve the NPGM catalyst durability.Finally,currently remained challenges and perspectives in the future on designing high-performance atomically dispersed NPGM catalysts toward fuel cell application are discussed.

Process Engineering Considerations of Electrochemical Storage

Thermodynamically, electric storages can be generally characterized as a type of regenerative machines able to operate in a work and a power machine mode. A consideration of the concentration term of the Nernst equation already shows a first principal difference between batch and flow processes, because the reaction coordinate depends on time for batch processes and on the flow coordinate for flow processes. Ionic substances may be stored within a volume surrounding the electrodes or on the surface of the electrodes itself. The volume concentrations of the reactants are thus a determining parameter of electrochemical storage beside voltage and the ratio of released electrons per reacting reference substance. Surface storage allows only batch processes while volume storage allows batch and flow processes. This characterization identifies the benefits of certain reactions regarding mass and volume related energy density in a simple way at a very early stage of development. It also allows a simple calculation of possible discharging times.

Realization and Analysis of Good Fuel Economy and Kinetic Performance of a Low-cost Hybrid Electric Vehicle

By using high-power and high-efficiency propulsion systems,current hybrid electric vehicles（HEVs） in market can achieve excellent fuel economy and kinetic performance.However,it is the cost of current HEVs that hinders HEVs coming into widespread use.A novel hybrid electric propulsion system is designed to balance HEV cost and performance for developing markets.A battery/supercapacitor-based hybrid energy storage system（HESS） is used to improve energy conversion efficiency and reduce battery size and cost.An all-in-one-controller（AIOC） which integrates engine electronic control unit（ECU）,motor ECU,and HESS management system is developed to save materials and energy,and reduce the influence of distribution parameters on circuit.As for the powertrain configuration,four schemes are presented：belt-driven starter generator（BSG） scheme,four-wheel drive HEV scheme,full HEV scheme,and ranger-extender electric vehicle（EV） scheme.Component selection and parameter matching for the propulsion system are performed,and an energy management strategy is developed based on powertrain configuration and selected components.Forward-facing simulation models are built,comprehending the control strategy based on the optimal engine torque for the low-cost hybrid electric propulsion system.Co-simulation of AVL CRUISE and Matlab/Simulink is presented and the best scheme is selected.The simulation results indicate that,for the best design,fuel consumption in urban driving condition is 4.11 L/（100 km） and 0-50 km/h accelerating time is 10.95 s.The proposed research can realize low-cost concept for HEV while achieving satisfactory fuel economy and kinetic performance,and help to improve commercialization of HEVs.

The Use of Hydrogen as a Fuel for Inland Waterway Units

Escalating apprehension about the harmful effects of widespread use of conventional fossil fuels in the marine field and in internal combustion engines in general, has led to a vast amount of efforts and the directing of large capital investment towards research and development of sustainable alternative energy sources. One of the most promising and abundant of these sources is hydrogen. Firstly, the use of current fossil fuels is. discussed focusing on the emissions and economic sides to emphasize the need for a new, cleaner and renewable fuel with particular reference to hydrogen as a suitable possible alternative. Hydrogen properties, production and storage methods are then reviewed along with its suitability from the economical point of view. Finally, a cost analysis for the use of hydrogen in internal combustion engines is carried out to illustrate the benefits of its use as a replacement for diesel. The outcome of this cost analysis shows that 98% of the capital expenditure is consumed by the equipment, and 68.3% of the total cost of the equipment is spent on the solar photovoltaic cells. The hydrogen plant is classified as a large investment project because of its high initial cost which is about 1 billion US$; but this is justified because hydrogen is produced in a totally green way. When hydrogen is used as a fuel, no harmful emissions are obtained.