【作者】 陈虹港；

【导师】 郑津洋；

【作者基本信息】 浙江大学 ， 化工过程机械， 2014， 博士

【摘要】 氢能因其具有储量丰富、燃烧值高、可再生等优点,被认为是21世纪最具发展前景的清洁能源,对于解决目前困扰世界的“能源短缺”和“环境污染”两大难题具有重要的战略意义。随着燃料电池技术的发展,氢燃料电池汽车正逐渐成为世界汽车厂商竟相研发的热点。高压储氢技术具有设备结构简单、充放速度快、压缩氢气能耗低等优点,是目前氢燃料电池汽车采用的主要储氢方式。复合材料氢气瓶承压能力强,质量轻,耐腐蚀性能好,是当前氢燃料电池汽车用氢气瓶的首选型式。由于储存的介质是易燃易爆的氢气,在使用过程中具有潜在的泄漏和爆炸危险,因此其安全性能是氢燃料电池汽车得以被公众广泛接受和市场化推广的关键。液压疲劳试验是检测复合材料气瓶宏观强度、安全裕度、结构设计合理性与可靠性的重要手段。美国、欧盟、日本、ISO和我国标准对于液压疲劳试验都提出了明确的要求。然而,目前国内还没有完全满足相关标准要求的70MPa复合材料气瓶液压疲劳试验的装置。另外,在进行液压疲劳试验时,应对压力和温度实施有效的控制,而对于复合材料气瓶在液压疲劳试验过程中的升压规律和温度变化规律的研究却很少,目前还没有一套能够准确控制升压速率和气瓶温度的方法。在国家高技术研究计划目标导向课题(“863"计划)项目“高压容器储氢技术和装备(项目编号：2006AA05Z143)”、国家重点基础研究发展计划("973"计划)课题“高密度车载储氢新体系及其安全性预测理论研究(项目编号：2007CB209706)”和国家质量监督检验检疫总局公益性行业科研专项经费项目“车用纤维缠绕高压氢气瓶标准基础研究”(项目编号：10-131)等的支持下,针对复合材料氢气瓶液压疲劳试验的要求,本文从液压疲劳试验装置研制,试验过程中压力和温度的变化规律以及升压速率和气瓶温度控制方法等方面开展研究,主要的研究内容和成果如下：(1)基于公称压力为70MPa的复合材料氢气瓶水压试验、爆破试验和常温压力循环试验的技术要求,确定了液压疲劳试验装置的介质种类、压力等级、输出流量等方面关键技术参数。综合考虑液压疲劳试验的要求、增压装置的特点和工作原理,提出了试验装置总体设计方案。对压力循环过程的实现方式进行研究,提出采用三通型和二通型气动换向阀联合作用的方式,有效降低了保压和卸压过程的能耗。对气动泵和柱塞泵流量特性进行分析,得到气动泵流量与输出压力和驱动气压的关系,基于增压泵流量特性,提出采用驱动气压调节和转速调节的方式实现气动泵和柱塞泵的流量调节。综合考虑了压力调节和流量调节的特性和相关元件的调节范围,提出通过流量控制的方式实现下限压力的调节。在此基础上进行流程设计,搭建液压疲劳试验装置,并通过试验验证了试验装置的功能。该装置的成功研制提升了我国复合材料氢气瓶安全性能检测能力。(2)在考虑介质的压缩性和气瓶容积变化的基础上,建立了复合材料氢气瓶增压过程的理论分析模型。基于水的状态方程,推导出压缩系数计算式。结合有限元分析方法,提出气瓶容积的计算方法。结合理论分析模型和介质压缩系数、气瓶容积及增泵流量特性,得到复合材料气瓶升压速率和升压时间的计算方法。通过对比计算结果和试验结果,验证了升压速率计算方法的准确性。分析了气瓶容积变化、介质温度和增压泵流量对升压速率的影响规律,结果表明：气瓶容积变化对升压速率存在较大影响,介质温度对升压速率的影响可以忽略,指出通过控制增压泵流量能有效控制升压速率。基于升压速率的计算方法,提出升压速率的控制方法,得到了保证升压速率要求下增压泵流量限制值。对于柱塞泵可采用调节电机转速的方式,对于气动泵可采用调节驱动气压的方式,并得到柱塞泵电机转速和气动泵驱动气压的取值范围。(3)基于变质量系统热力学理论,建立了复合材料氢气瓶压力循环试验过程的热力学模型,模型考虑了介质的压缩与膨胀、介质与内壁的对流传热、气瓶壁的导热以及外壁与环境的自然对流换热等。开展了复合材料氢气瓶压力循环过程温度变化试验研究,通过试验验证了理论模型的准确性。基于该热力学模型,对氢能与燃料电池国际合作伙伴计划(International Partnership for Hydrogen and Fuel Cell in Economy, IPHE)组织循环对比试验所用24.8MPa、54L的Ⅳ型气瓶在充入介质温度、循环频率、环境温度等参数影响下的压力循环试验过程进行了数值模拟研究,得到了各参数对气瓶平衡温度的影响规律。研究结果表明：经过一定的循环次数,气瓶温度逐渐达到稳定状态；气瓶壁面平衡温度与充入介质温度和环境温度近似呈线性关系,循环频率对气瓶壁面平衡温度的影响并不明显。依据数值计算结果得出了较为精确的气瓶平衡温度计算公式。基于该平衡温度计算公式,提出了控制气瓶温度的方法,通过控制充入介质温度可以有效控制气瓶温度,并得出保证气瓶温度要求的不同试验条件下充入介质温度取值范围。更多还原

【Abstract】 Hydrogen has become the most promising clean energy of21st century because of its excellent advantages such as rich reserve, high combustion efficiency and reproducible ability. It has important strategic significance for solving the problems of energy shortage and environmental pollution puzzling all over the world. With the development of fuel cell technology, hydrogen fuel cell vehicle has become the focus of the world automobile manufacturers.High pressure gaseous hydrogen storage is the most popular and mature method for fuel cell vehicle due to its technical simplicity, fast filling-releasing rate and low energy consumption for compressing hydrogen. Composite cylinder as the first choice for on-board hydrogen storge has the advantages of high-pressure-resistant ability, light weight and corrosion resistance. The safety performance of high-pressure hydrogen storage with potential risk of leakage and explosion is the important factor that infuences the public to accept fuel cell vehiceles and marketing promotion.Hydraulic fatigue test is the important means to detect macroscopic strength, safety margin, construction rationality and reliability of composite cylinder. Definite requirements have been proposed in relevant standards of US, EU, Japan, ISO and China. However, it is found that there is no hydraulic fatigue test system for70MPa composite cylinder in China. Pressure and temperature should be controlled during hydraulic fatigue test. However, little research has been done on the law of pressure rise and temperature variation, and contorl method of pressure and temperature during hydraulic fatigue test has not been established.Researches on development of hydraulic test system and pressure rise and temperature rise of high-pressure hydrogen cylinder during hydraulic test and pressure cycling test is conducted in this paper, which is supported by the National High Technology Research and Development Program of China (863Program)"Technology and equipment of high pressure hydrogen storage vessels"(No.2006AA05Z143), Key Project of China National Programs for Fundamental Research and Development of China (973Program)"New high-density on-board hydrogen storage system and its theoretical safety prediction research"(No:2007CB209706), and the nonprofit industry research project of General Administration of Quality Supervision, Inspection and Quarantine of the People’s Republic of China(No:10-131). The main contents and conclusions of this paper are as follows:(1) Based on requirements of hydraulic test, burst test and pressure cycling test for70MPa composite hydrogen cylinder, parameters of hydraulic fatigue test system are determined such as type of medium, pressure class and flow rate. Considering the feature of hydraulic fatigue test and working principle of pressure device, a general design scheme of hydraulic fatigue system is proposed. The combination of3-way and2-way pneumatic directional valves is proposed by studing on the realization modes of pressure cycle, which effectively reduces energy consumption during pressure keeping and relief. The flow rate of air driven pump with output pressure and pneumatic pressure through analyzing the flow characteristics of booster pumps. Motor speed and pneumatic pressure regulation are used to change the flow rate for air driven pump and plunger pump. And flow control is used to control the lower limit pressure. On this basis, a process design is conducted and the hydraulic fatigue test system for70MPa composite hydrogen cylinder is built which improves detection ability of safety performance and provides strong support for design and experimental study of high pressure composite hydrogen cylinder.(2) A theoretical analysis model has been established for pressurization of composite cylinder in which compressibility of medium and volume change of cylinder are comprehensively considered. Based on the equation of state of water, a formula of compressibility is derived. A calculation method for the volume of composite cylinder with pressure is proposed by finite element method. A calculation method of pressure rise rate and time is established combined with the theoretical analysis model, compressibility of water, volume of composite cylinder and flow characteristics of booster pumps. The calculation method is verified by experimental data. Effects of the volume change of cylinder, medium temperature and flow rate of pump on the pressure rise rate are investigated. It is revealed that the pressure rise rate is greatly affected by volume change of composite cylinder and is little affected by medium temperature, and pressure rise rate can be controlled by controlling the flow rate of pump. Furthermore, the control method of pressure rise rate is brought out. The value range of motor speed for plunger pump and pneumatic pressure for air driven pump is obtained.(3) Based on the theory of variable mass thermodynamics system, a thermodynamic model has been established for pressure cycling process, in which compression and expansion of medium, convective heat transfer between medium and inner surface, heat conduction in cylinder, and convective heat transfer between outer surface and environment are fully considered. A experimental study is taken on the temperature rise of composite hydrogen cylinder during pressure cycling test. The accuracy of the model is verified by the comparison between the experimental and simulation results. The thermodynamic model is employed to analyze the influence law of test parameters on equilibrium temperature of cylinder. It is shown that the temperature of cylinder surface is stable after several cycles, the equilibrium temperature of cylinder surface increase linearly with the increase of filling medium temperature and ambient temperature, and frequency has no significant effect on equilibrium temperature of cylinder surface for24.8MPa/54L type4composite cylinder used in IPHE round robin test. Based on simulation results, an equation for equilibrium temperature of cylinder surface is put forward. Furthermore, the control method of temperature of cylinder is brought out. Temperature of cylinder can be controlled by controlling the filling medium temperature. The value range of filling medium temperature for test requirement with various conditions was obtained.更多还原