Development of a gaseous and solid-state hybrid system for stationary hydrogen energy storage

Hydrogen can serve as a carrier to store renewable energy in large scale.However,hydrogen storage still remains a challenge in the current stage.It is difficult to meet the technical requirements applying the conventional storage of compressed gaseous hydrogen in high-pressure tanks or the solid-state storage of hydrogen in suitable materials.In the present work,a gaseous and solid-state(G-S)hybrid hydrogen storage system with a low working pressure below 5 MPa for a 10 kW hydrogen energy storage experiment platform is developed and validated.A Ti-Mn type hydrogen storage alloy with an effective hydrogen capacity of 1.7 wt%was prepared for the G-S hybrid hydrogen storage system.The G-S hybrid hydrogen storage tank has a high volumetric hydrogen storage density of 40.07 kg H_(2)m^(-3) and stores hydrogen under pressure below5 MPa.It can readily release enough hydrogen at a temperature as low as-15C when the FC system is not fully activated and hot water is not available.The energy storage efficiency of this G-S hybrid hydrogen storage system is calculated to be 86.4%-95.9%when it is combined with an FC system.This work provides a method on how to design a G-S hydrogen storage system based on practical demands and demonstrates that the G-S hybrid hydrogen storage is a promising method for stationary hydrogen storage application.

Molten Salts and Applications Ⅱ: 565℃ Molten Salt Solar Energy Storage Design, Corrosion, and Insulation

Excess energy from various sources can be stored in molten salts (MS) in the 565 °C range. Large containers can be used to store energy at excess temperatures in order to generate eight hours or more of electricity, depending on the container size, to be used during peak demand hours or at night for up to a week. Energy storage allows for a stable diurnal energy supply and can reduce the fluctuation due to weather conditions experienced at thermal solar power stations. Supported by Office of Naval Research (ONR), this paper discusses the design considerations for molten salt storage tanks. An optimal molten salt storage tank design layout is presented, as well as alternative designs for the storage tanks. In addition, the costs and corrosion effects of various molten salts are discussed in order to show the effects these considerations have on the design process.

Comprehensive Molten Salt Storage Shell and Supporting Structure Design and Analysis-Part I:A Conductive and Convective Theoretical Heat Transfer Analysis for Molten Salt Cylindrical Shells at 565℃ and 700℃

In this paper a full theoretical thermal analysis of a large molten salt container,80-foot in diameter and 46-foot high,including a four-foot elliptic shell roof,is presented for two temperatures,the standard 565℃ and a futuristic 700℃,which substantially improves the efficiency of the molten salt containers through the use of a highly stable chloride salt called SS700(SaltStream 700).The theoretical analysis includes conductive and convective heat transfer analysis in the steel container,elliptic roof shell,the fiberglass insulation,and firebrick insulation,and includes thermal insulation designs to safeguard against energy losses at high temperatures.The underlying soil and the high temperature concrete foundation were analyzed theoretically using conductive heat transfer,however the area surrounding the soil surface around the bottom of the molten salt storage tank had convective heat transfer analysis included.The final designs presented in this paper seek to limit heat losses to a maximum of 250 W/m^(2) while being able to operate at a minimum external ambient temperature of-10℃,which determines the thicknesses of the fiberglass and firebrick insulation.

Recent Progress on Thermal Energy Storage for Coal-Fired Power Plant

With countries proposing the goal of carbon neutrality,the clean transformation of energy structure has become a hot and trendy issue internationally.Renewable energy generation will account for the main proportion,but it also leads to the problem of unstable electricity supply.At present,large-scale energy storage technology is not yet mature.Improving the flexibility of coal-fired power plants to suppress the instability of renewable energy generation is a feasible path.Thermal energy storage is a feasible technology to improve the flexibility of coal-fired power plants.This article provides a review of the research on the flexibility transformation of coal-fired power plants based on heat storage technology,mainly including medium to low-temperature heat storage based on hot water tanks and high-temperature heat storage based on molten salt.The current technical difficulties are summarized,and future development prospects are presented.The combination of the thermal energy storage system and coal-fired power generation system is the foundation,and the control of the inclined temperature layer and the selection and development of molten salt are key issues.The authors hope that the research in this article can provide a reference for the flexibility transformation research of coal-fired power plants,and promote the application of heat storage foundation in specific coal-fired power plant transformation projects.

Comprehensive Molten Salt Storage Shell and Supporting Structure Design and Analysis-Part II:A Conductive and Convective Numerical Finite Element Heat Transfer Analysis for Molten Salt Cylindrical Shells at 700℃,and Comparison with Theoretical Analysis

In this paper a finite element thermal analysis model-using COMSOL-of a large molten salt container,80-foot in diameter and 46-foot high that includes a four-foot elliptic shell roof,is presented for a futuristic 700℃ design,which uses a highly stable chloride salt called SS700(SaltStream 700)that improves the efficiency of the tank when compared to the traditional 565℃.The FEA(finite element analysis)includes conductive and convective heat transfer analysis in the steel container,elliptic roof shell,the fiberglass insulation,and firebrick insulation,and includes thermal insulation designs to safeguard against energy losses at high temperatures.The underlying soil and the high temperature concrete foundation were analyzed by finite element using conductive heat transfer,however the area surrounding the soil surface around the bottom of the MS storage tank had convective heat transfer analysis included.The finite elements analyses presented are to verify the final fiberglass and firebrick insulation designs,which seeks to limit heat losses to a maximum of 250 W/m^(2) while being able to operate at a minimum external ambient temperature of-10℃.These results are also compared to previously calculated theoretical results.

Modeling and Simulation of Hydrogen Energy Storage System for Power-to-gas and Gas-to-power Systems

By collecting and organizing historical data and typical model characteristics,hydrogen energy storage system(HESS)-based power-to-gas(P2G)and gas-to-power systems are developed using Simulink.The energy transfer mechanisms and numerical modeling methods of the proposed systems are studied in detail.The proposed integrated HESS model covers the following system components:alkaline electrolyzer(AE),highpressure hydrogen storage tank with compressor(CM&H_(2) tank),and proton-exchange membrane fuel cell(PEMFC)stack.The unit models in the HESS are established based on typical U-I curves and equivalent circuit models,which are used to analyze the operating characteristics and charging/discharging behaviors of a typical AE,an ideal CM&H_(2) tank,and a PEMFC stack.The validities of these models are simulated and verified in the MicroGrid system,which is equipped with a wind power generation system,a photovoltaic power generation system,and an auxiliary battery energy storage system(BESS)unit.Simulation results in MATLAB/Simulink show that electrolyzer stack,fuel cell stack and system integration model can operate in different cases.By testing the simulation results of the HESS under different working conditions,the hydrogen production flow,stack voltage,state of charge(SOC)of the BESS,state of hydrogen pressure(SOHP)of the HESS,and HESS energy flow paths are analyzed.The simulation results are consistent with expectations,showing that the integrated HESS model can effectively absorb wind and photovoltaic power.As the wind and photovoltaic power generations increase,the HESS current increases,thereby increasing the amount of hydrogen production to absorb the surplus power.The results show that the HESS responds faster than the traditional BESS in the microgrid,providing a solid theoretical foundation for later wind-photovoltaic-HESS-BESS integration.

基于实测数据立式热水储能罐罐壁力学特性分析

为掌握立式储能罐结构的受力特征,基于某30 000 m~3立式热水储能罐项目,依托远程监测技术采集了运行状态下罐壁应力和温度数据,将采集结果与考虑罐底摩擦接触约束建立的有限元模型分析结果进行比较,验证了此有限元模拟方法的合理性;依托实测温度数据,研究了立式储能罐罐壁热力耦合作用下罐壁位移以及应力分布规律。结果表明:罐壁底部和顶部为温度影响敏感区域,温度升高,使其产生压应力;对于环向应力,在底部受温度荷载影响较顶部更显著;而对于竖向应力,影响主要是罐壁底部;温度对罐壁变形影响较大,在空罐时,最大位移位置出现在罐壁最顶端;而满罐时最大变形位置出现在中上部的位置,温度作用大于静水压力对罐壁变形的影响。

液氢制-储-运-加关键技术发展现状及展望

【目的】液态储运是实现氢气大规模、远距离储运,保证氢能规模化应用的有效途径之一。目前,我国针对液氢制备、储运及加注领域的研究相对较少,为此,对该领域关键技术发展现状进行了分析。【方法】对比了高压气态、液态及固态储氢技术的优缺点;综述了液氢制备过程中的主要液化方法、液氢储存绝热技术与关键材料;分析了不同液氢运输方式与装备的特点;梳理了液氢加氢站建设情况,并对比了液氢加注技术;阐述了液氢主要应用领域和产业化模式,并对近年来我国液氢储运专利技术进行了统计分析。【结论】提出了我国液氢储运发展面临的“卡脖子”难点及亟需技术攻关的方向。研究结果可为液氢关键技术的研究与装备的研制提供参考。

双层相变材料复合水箱蓄热特性研究

以双层相变材料复合水箱为研究对象,通过数值模拟和实验研究的方法,对该水箱的蓄热特性进行模拟分析与实验验证,对比分析单、双层相变材料复合水箱的热特性,探究双层相变材料位置对复合水箱蓄热特性的影响规律。研究结果表明,与单层相变材料复合水箱相比,双层相变材料复合水箱的热分层更好,蓄热能力得到提升,双层相变材料复合水箱较普通水箱的蓄热量提高9.7%。双层相变材料距离进出水口位置较远时,相变材料完成熔化的时间更接近,更有利于蓄热水箱的热分层。

计及蓄热罐与管网虚拟储能热电联供系统的经济运行优化分析

本文建立计及蓄热罐与管网虚拟储能热电联供系统模型,探讨不同储能装置配置(如无储能装置、含虚拟储能、含蓄热罐、含蓄热罐与虚拟储能)下负荷场景、燃煤价格、管网长度对系统运行成本的影响。结果表明:含蓄热罐与虚拟储能的储能配置使得热电联供系统的运行成本大幅降低,且当热电负荷波动较大时,运行成本降幅更大,如工业负荷场景下降幅达26.12%;燃料价格上涨使得系统运行成本线性增加,但相比于无储能装置,含储能装置系统的运行成本仍然较低,经济性更好;由于管网储能容量限制以及管网热损的影响,存在一个最佳管长使得系统运行成本最小。

光伏蓄能恒温库系统数值模拟分析

为进一步降低热泵系统冬季能耗,减少恒温库能源消耗情况,本文提出了一种新型光伏驱动蓄能型恒温库系统。基于TRNSYS仿真系统,构建了太阳能-热泵蓄能型热力耦合数学模型,对该恒温库系统进行数值模拟和理论分析。结果显示,在新型光伏驱动蓄能型恒温库系统运行下,库内温度可以稳定维持在-2.0~3.7℃保持24 h,在稳定运行过程中热泵系统运行效率保持在3.0~4.0,系统平均性能系数(COPa)可以达到1.9,系统运行功率在0~0.7 kW,系统24 h累计制热量达到了18.0 kW·h,日平均累计消耗市电仅6.8 kW·h。结果表明,该系统可以为节能型恒温库提供一种设计依据。

储罐液位控制节能参数仿真研究

在石油化工行业生产过程中,储罐作为一种最普通的设备被广泛应用。为保证储罐安全,储罐液位须限定在一定范围内,液位控制达到稳态的时间,直接关系到系统的稳定性及节能性。针对如何精准确定控制参数这一问题,采用仿真手段对储罐的液位控制进行研究,找到提高液位控制的节能参数,利用WINCC 7.3上位机编程软件搭建上位机工艺流程,在模块中插入C脚本语言,达到与实际运行一致的工艺参数,在STEP7 V5.5软件搭建下位机PID仿真程序,两个软件做联合仿真。仿真结果表明:在同等工况下(1000 m^(3)缓冲罐,直径11.5 m,高度10.725 m,污水外输泵排量85 m^(3)/h),比例值采用10产生的液位变化曲线达到稳态的时间与比例值采用5液位变化曲线达到稳态的时间相比缩短4 min;初步估算,每天每个泵将减少高频运行时间约为2 h,如果按照72 kW功率计算,每台泵每天节能约为72 kWh,每年节能约为2.628×10^(4)kWh,按照0.54元/kWh电价计算,每台泵每年节约运行费用1.42万元。在油田实际生产运行中,优化控制参数能起到较好的节能降耗作用,产生良好的经济效益。

压缩空气抽水蓄能系统蓄能罐参数配置分析

为获得压缩空气抽水蓄能(pumped hydro combined with compressed air energy storage system,PHCA)系统蓄能罐子系统在实际运行中具有较高能量密度与蓄能效率的参数配置,对系统中蓄能罐子系统进行热力学建模,分析了其压力配置、换热条件、流量配置对于蓄能罐子系统效率和能量密度的影响规律,结果表明:对于额定存储压力,总有与之对应的一个最优初始压力可以使得能量密度达到最大值,存储压力与最优初始压力的比值在2~3之间,对应压力配置的蓄能效率稳定在92%~93%之间;传热系数和存储时间在一定配置范围内会使系统陷入低效率区,在蓄能罐的设计中,应当评估出其换热能力避免低效率区;运行过程中,存储时间对于蓄能效率的影响较大,选择合适的水泵水轮机工作流量可以保证效率,在短存储时间时,采用的配置方法为高压缩、高膨胀流量,当存储时间变长后,应当同时减少压缩和膨胀流量。研究结果可为该系统的设计与运行提供理论依据。

大型蓄热球罐温度场的模拟与试验研究

基于新型储能如兆瓦级压缩空气储能和含高比例新能源电力消纳对于大规模、高中温介质储能技术的实际需求,采用大型承压球罐作为蓄热容器的工程项目越来越多,球罐具有相同容积表面积最小、承压能力比柱罐更高等明显优势,但也因球罐其特殊的形状,在水的斜温层蓄热应用上较少。本文采用了仿真和试验的方式研究了大型蓄热球罐在高参数水蓄热和放热过程中内部温度场,对比分析了罐体内温度变化、斜温层水容积、球罐蓄热效率。试验结果表明通过布水优化设计,200 m^(3)球罐的实际蓄热效率超过91%。本文研究结果验证了球罐作为一种新的水蓄热容器特别是在冷热同罐的高参数水蓄热系统上的可行性,为后续大型中温球罐蓄热系统设计、应用提供有益参考。

相变能+热泵供暖系统实验研究

针对我国北方山区冬季没有合适热源供暖的问题,基于水-冰相变凝固换热原理,利用水相变的凝固潜热作为热泵机组的低温热源,设计研发了相变能+热泵供暖系统并进行实验研究。研究表明:系统在凝固换热阶段,结冰厚度达到30 mm时,综合传热系数为151 W/(m^(2)·K),系统有效能效比为3.52;本次设计循环周期为4 h,传热系数取150 W/(m^(2)·K),确定U型蓄冰槽的储能量与换热量;融冰能耗占比为5.6%,融冰时间为26 min;实验系统可满足300 m^(2)房屋的供暖需求。

Comprehensive Molten Salt Storage Shell and Support Design and Analysis Ⅲ: A Complete 700 ℃ Thermal-Structural Interaction Design Using Theoretical Analysis of an 80 Foot Diameter and 46 Foot High MS Storage Shell Including Structural, Conductive and Convective Thermal Stress Analysis

The paper discusses the structural design of a futuristic 700℃ MS(Molten salt)Storage Shell,which considers many elements in providing an adequate and comprehensive design.In designing the structural carbon steel for the tank,temperature is an important consideration because steel has a yield strength at 700℃,that is 33%of its nominal yield,while the Young’s Modulus at 700℃ is 50%of its nominal Young’s Modulus.At this temperature,thermal stresses can yield or tear the structural steel unless free expansion of the structure is allowed.This is accomplished with sand layers below each layer of steel and by including a small gap behind the side carbon steel layer.A roof shell design for the tank is also presented in this paper,comparing various roof shell types and their designs.All designs include thermal insulation and an inner stainless steel corrosion layer to protect the structural and thermal insulation elements of the tank from the MS.

液化烃储罐投用及检修前置换节能探讨

新建液化烃储罐投用前,需对储罐内空气进行置换,降低储罐内气体中氧含量<3%。储存过液化烃储罐检修前需对罐内烃气体进行置换,若储存烃的爆炸下限≥4%,置换后罐内气体的烃含量要求≤0.5%;若储存烃的爆炸下限<4%时,置换后罐内气体烃含量要求≤0.2%。在石化行业,通常采用的方法有水置换法和氮气置换法,由于水置换法使用过的水需要二次处理(目前储罐都趋于大型化,一般都有几千立方米),会增加企业污水处理场负荷和水处理成本,我国是个淡水资缺乏的国家(特别是北方地区),用水置换法也会造成水资源的浪费,故通常采用氮气置换法。

层式结晶中典型能量系统

近年来,熔融结晶技术作为生产高纯度产品的重要技术在相关行业的应用愈发广泛,在国内外备受关注。本文简述了熔融结晶技术的特点及其分类,重点介绍了层式结晶的操作过程和不同阶段所需的换热要求,并详细说明了一种典型的能量系统设计,其包括了系统的组成、设备功能、工艺流程、蓄能罐充放能过程。本能量系统不仅可以应用于具有严格换热要求的层式结晶过程,亦可以用于其它类似的工况。

谷电储能供暖系统优化设计方法

为应对北方清洁供暖,本文提出了一种谷电储能供暖系统,旨在充分利用地热能和储能技术的优势,满足冬季清洁供暖。首先,对该系统进行了介绍。然后,针对该系统提出了一种优化设计方法,在系统满足建筑在典型年的逐时热负荷要求的基础上,以典型年的年化总成本(包括年化初始成本和年化运行成本)为目标函数,进而通过求解最小目标函数对各设备容量进行优化设计。其中,在典型年的年化运行成本计算中,将所采用的系统运行策略进行了详细介绍。最后,以北方地区某多层办公建筑冬季供暖为例进行计算。在未采用优化设计方法前,系统所需的年化总成本为84.26万元,而采用该方法后,该系统所需的最小年化总成本为61.90万元。经过优化设计后,地源热泵机组额定制热量、蓄热水箱体积以及电锅炉额定制热量的最佳容量分别为1276369 W、1022 m^(3)和2604791 W。本文提出的综合能源复合系统及其优化设计方法为北方地区提供了清洁供暖的选择,对我国能源转型具有重要意义。

新能源汽车车载储氢罐设计中CATIA的应用研究

随着环境危机的日益严峻,具备清洁、高效、可再生等特点的氢能源备受人们关注,发展氢能源汽车要解决的首要问题就是车载储氢装置。本文结合吉利氢能源客车储氢罐数据和国内外的研究,通过CATIA设计了高压气态储氢罐三维模型,为新能源客车企业的汽车工程师们提供了一套车载储氢罐的设计方案。