共查询到18条相似文献,搜索用时 156 毫秒
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基于金属氢化物储氢反应,建立了相变材料蓄热的固体储氢反应器模型,模拟研究了吸氢压力等操作参数及相变材料的相变温度、固(液)态导热系数、相变潜热等物性参数对固体储氢反应器工作过程的影响. 结果表明,相变材料的固态导热系数和相变潜热对固体储氢反应器性能的影响较小,相变温度和液态导热系数对反应器性能影响较大. 相变温度越低,液态导热系数越大,储氢反应器性能越好. 在使用最优的相变材料储能时,提高充入氢气的压力可加快反应速率,强化相变材料的传热,有助于进一步优化反应器的储氢性能. 相似文献
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由TiMn合金的二元相图出发,研究了TiMn_(1.2)(VFe)_(0.8)储氢合金的制备及其储氢性能。结果表明,采用两步熔炼的方法可以快速制备该合金,而且所得合金成分均匀,储氢性能稳定。X射线衍射分析表明,合金中主要存在TiMn基Laves相,经退火热处理后合金中出现了新的合金相;合金的吸放氢量测试表明,在室温和3.04 MPa的吸氢条件下,该合金在353K、终止压力为101.325 kPa时的放氢量超过200 ml·g~(-1),在相同的吸放氢条件下,经退火热处理的合金其放氢量有所提高,可以达到220 ml·g~(-1),质量比接近2%;合金吸放氢的压力-组成-温度(PCT)测试表明退火前后合金的吸放氢热力学性能略有改变,合金退火后出现了新的吸放氢平台。 相似文献
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为开发出具有高循环寿命和高储氢性能的新能源汽车用稀土镁基储氢合金,考察了铸态和退火态的铸锭/快淬(La0.7Mg0.3)Nix(x=2.0、2.5、3.0)储氢合金的微观结构、物相组成和储氢特性。结果表明,当x=2.5时快淬法储氢合金具有较好的吸放氢平台压力,PCT曲线中体现出完全脱氢特征,吸氢容量约为1.44%(质量分数)。经过850~950 ℃退火处理,铸锭法(La0.7Mg0.3)Ni2.5储氢合金相较(La0.7Mg0.3)Ni2.0储氢合金具有更高的吸放氢平台压和更宽的吸放氢平台,表明前者具有相对更好的吸放氢性能;不同退火温度下(La0.7Mg0.3)Ni2.5储氢合金的吸放氢平台压较为接近,吸氢和放氢容量可达到1.6%(质量分数)。铸锭法和快淬法(La0.7Mg0.3)Nix储氢合金中的LaNi5和(LaMg)Ni3相会随着退火温度的升高而逐渐转变为(LaMg)2Ni7相;铸锭法和快淬法(La0.7Mg0.3)Ni2.5储氢合金的表面粉末颗粒分别在退火温度为950 ℃和900 ℃时最为细小。 相似文献
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Go Young Moon Sang Seo Lee Ga Ram Yang Kwang Ho Song 《Korean Journal of Chemical Engineering》2010,27(2):474-479
Sodium borohydride has received much attention from fuel cell developers due to its high hydrogen storage capacity. In this
study, organic acid solutions such as malic, citric, acetic acids were successfully utilized to accelerate and control hydrogen
generation from stabilized sodium borohydride solutions. The generated hydrogen by malic acid was then continuously supplied
to a PEMFC single cell. A power density of 168 mW cm−2 was achieved with a hydrogen flow rate of 0.050 L min−1 that was generated by adding 10 wt% aqueous malic acid to the stabilized sodium borohydride solution at an air flow rate
of 0.11 L min−1 without humidification. Further increase of power density to 366 mW cm−2 is practicable by maintaining a precise hydrogen flow rate of 0.3 L min−1. The current study focuses on the development of an instant hydrogen generation method for micro fuel cell applications.
We successfully demonstrated that fast and direct generation of hydrogen could be achieved from stabilized borohydride using
inexpensive organic acid solutions rather than expensive metal catalysts and a PEMFC single cell could be operated by generated
hydrogen. 相似文献
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Chakkrit Na Ranong Gustavo Lozano Jobst Hapke Wilfried Roetzel Georg Fieg Jose Bellosta von Colbe 《Chemical engineering science》2011,(20):4654
The paper presents a model-based investigation of a metal hydride reactor applied as a solid state hydrogen storage device. The elements of a metal hydride reactor are hydrogen supply duct, internal hydrogen distribution, hydride bed, reactor shell and the flow domain of the heat transfer fluid. Internal hydrogen distribution and hydride bed are porous media. Therefore, hydrogen flows through non-porous and porous regions during its reversible exothermic absorption and endothermic desorption, respectively. The interface between porous and non-porous regions is a discontinuity with respect to energy transport mechanisms. Hence, Danckwerts-type boundary conditions for the energy balance equation are introduced. Application of the first and second law of thermodynamics to the interface reveals that temperature jumps may occur at the hydrogen inlet but are not allowed at the hydrogen outlet. Exemplarily the loading behavior of a metal hydride storage tank based on sodium alanate is analyzed. It is demonstrated and experimentally validated that only Danckwerts-type boundary conditions predict the important cooling effect of the inlet hydrogen on the exothermic absorption process correctly. 相似文献
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氢气循环泵是质子交换膜燃料电池(PEMFC)发动机核心零部件之一,本文针对氢气密度低,且氢气极易发生泄漏的问题,设计了一种结构紧凑的旋涡式氢气循环泵。以该氢气循环泵的三维流场为研究对象,建立了泵腔流场的CFD数值计算模型,利用Fluent软件进行内部流场仿真计算,分析了不同转速下的氢气循环泵的的性能特性,确定了该氢气循环泵的最小转速,通过与实验数据的对比分析,验证了该计算模型的可行性和准确性。实验结果表明:氢气循环泵电机转速控制稳定,气密性良好;氢气循环泵随着进口压力提高,氢气循环量将逐渐增大,在16000r/min条件下,氢气泵入口从35kPa升到145kPa,氢气循环流量从140L/min增加到330L/min,氢气循环量满足30kW燃料电池发电系统需求。 相似文献
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David C. Calabro Randall D. Partridge Paul J. Berlowitz Barbara Carstensen Harold W. Deckman Philip L. DaPrato Frank Hershkowitz Richard F. Socha 《Catalysis Today》2007,129(3-4):380-390
This paper describes the operation of a dual functional, membrane/catalytic COx methanator, hydrogen purifier that is well-suited for an integrated fuel processor/fuel cell power system. In combination with a pressure swing reformer (PSR) and a PEMFC, the system provides high overall efficiency and portability for distributed power or onboard vehicle use. Gas testing results illustrate the ability of the purifier to produce fuel cell purity hydrogen at peak power flux. The durability of this purifier is shown by its ability to meet target hydrogen purity even with a membrane that permeates >3000 ppm CO. Gas purge streams from both fuel cell electrodes are combined with the membrane retentate and combusted in the PSR combustion cycle to provide heat for the reforming reaction leading to high thermal efficiency. Most significantly, it is shown that staging of this purifier, enables recovery of some fraction of the purified hydrogen at pressures substantially approaching that of the feed hydrogen partial pressure. This creates an onboard source of high pressure hydrogen to be optionally fed to a storage device for use during vehicle startup, or to the fuel cell, either directly or via the storage device, under high power load conditions. The beneficial impact of this two-stage, dual functional purifier on membrane cost, dependability and fuel processor/fuel cell integration, will be discussed. 相似文献
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An autothermal membrane reformer comprising two separated compartments, a methane oxidation catalytic bed and a methane steam reforming bed, which hosts hydrogen separation membranes, is optimized for hydrogen production by steam reforming of methane to power a polymer electrolyte membrane fuel cell (PEMFC) stack. Capitalizing on recent experimental demonstrations of hydrogen production in such a reactor, we develop here an appropriate model, validate it with experimental data and then use it for the hydrogen generation optimization in terms of the reformer efficiency and power output. The optimized reformer, with adequate hydrogen separation area, optimized exothermic‐to‐endothermic feed ratio and reduced heat losses, is shown to be capable to fuel kW‐range PEMFC stacks, with a methane‐to‐hydrogen conversion efficiency of up to 0.8. This is expected to provide an overall methane‐to‐electric power efficiency of a combined reformer‐fuel cell unit of ~0.5. Recycling of steam reforming effluent to the oxidation bed for combustion of unreacted and unseparated compounds is expected to provide an additional efficiency gain. © 2010 American Institute of Chemical Engineers AIChE J, 2011 相似文献
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To obtain high hydrogen sorption capacity and reduce the time of the cycle (adsorption/desorption) in the gas storage system a new composite material (metal hydride particles on the activated carbon fibre matrix) was suggested. Different adsorbent materials such as activated carbon fibre “Busofit”, granular activated carbon and new composite sorbent (metal hydride La0.5Ni5Ce0.5 particles on the activated carbon fibre “Busofit”) were tested. Effect of the carbon sorbent nature and metal hydride content is important to choose the optimal sorbent bed.In this paper, a thermally regulated storage system for hydrogen was numerically analyzed and experimentally validated. A two-dimensional transient model was used to analyze the influence of the thermal control on the operating characteristics of the flat sectional vessel. The evolution of the temperature, pressure and volumetric density of hydrogen inside the vessel during the charging/discharging is discussed. It was shown that heat pipe based thermal control of the process increase the efficiency of the hydrogen storage. Such vessels are interesting to be applied in fuel cells used for vehicle or dual-fuel engine car (hydrogen/gasoline, hydrogen/methane). 相似文献
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Mikhail Granovskii Ibrahim Dincer Marc A. Rosen 《Chemical engineering journal (Lausanne, Switzerland : 1996)》2006,120(3):193-202
The high temperature of the air in power generation gas-turbine cycles involving natural gas (mainly methane) oxidation accounts for the utilization of ion-conductive membranes within solid oxide fuel cells (SOFCs) and membrane reactors (MRs). In SOFCs, the electricity is directly derived from the chemical exergy of methane (SOFCs with internal methane reforming are considered here). Within a membrane reactor (MR), which is considered a substitute for combustion chambers in traditional gas-turbine units, the ion-conductive membranes separate oxygen from air and allow the flow of the hot combustion products (carbon dioxide and steam) to be separated from air. It permits the use of combustion products which are not diluted in nitrogen in the process of methane conversion into hydrogen. A modified gas-turbine cycle that includes a SOFC stack, an MR (instead of a traditional combustion chamber), and a catalytic reactor to convert methane to hydrogen is proposed. An exergy analysis of the proposed system is conducted to evaluate its exergy efficiency and the exergy losses for the processes occurring within the system. It is shown that, in comparison to the traditional gas-turbine cycle, there is a significant reduction (more than three times) in the exergy losses for the most irreversible process occurring in the system, natural gas combustion. It is also found that the proposed cogeneration scheme, including both power generation and the industrial catalytic conversion of methane to hydrogen, permits improved efficiencies for both technologies. The efficiency of this cogeneration, as well as the reduction in exergy losses, is demonstrated by the following observation: if the value of energy (exergy) efficiency of hydrogen production is considered equal to that for a traditional process, the corresponding thermal (energy) efficiency for electricity generation would reach values of 80–96% depending on the efficiency of a SOFC stack. The combined SOFC and MR application also eliminates the possibility of toxic nitrogen oxides formation and, at the same time, makes carbon dioxide removal from flue gases feasible (due to its high concentration). The development of the proposed technology is especially important, within the context of the hydrogen economy, if the produced hydrogen is used as a fuel for fuel cell vehicles. 相似文献