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排序方式: 共有377条查询结果,搜索用时 15 毫秒
91.
Microreactor technology is a promising approach in harnessing the high energy density of hydrocarbons and is being used to produce hydrogen-rich gases by reforming of methanol and other liquid hydrocarbons. However, on-demand H2 generation for miniature proton exchange membrane fuel cell (PEMFC) systems has been a bottleneck problem, which has limited the development and demonstration of the PEMFC for high-performance portable power. A number of crucial challenges exist for the realization of practical portable fuel processors. Among these, the management of heat in a compact format is perhaps the most crucial challenge for portable fuel processors. In this study, a silicon microreactor-based catalytic methanol steam reforming reactor was designed, fabricated, and demonstrated in the context of complete thermal integration to understand this critical issue and develop a knowledge base required to rationally design and integrate the microchemical components of a fuel processor. Detailed thermal and reaction experiments were carried out to demonstrate the potential of microreactor-based on-demand H2 generation. Based on thermal characterization experiments, the heat loss mechanisms and effective convective heat coefficients from the planar microreactor structure were determined and suggestions were made for scale up and implementation of packaging schemes to reduce different modes of heat losses. 相似文献
92.
93.
Harvey H.F. Wang S.C. Chen S.Y. Yang G.T. Yeh M.H. Rei 《International Journal of Hydrogen Energy》2012
The effect of the heat transfer area and the thermal conductivity of the reactor materials are evaluated with three identical structured reactors having multiple columned-catalyst bed and using three different reactor materials, aluminum alloy, brass and stainless steel. A series of compact methanol reformers are then designed and fabricated with the use of large reactor surface area in catalyst beds and high heat transfer constant to produce hydrogen fuel with 2–4 ppm of CO for the fuel cell (FC) power generation. The same design principle is successfully used for easy scale up of the reactor capacity from 250 L/h to 10,000 L/h. This low CO hydrogen (68–70%) used as the fuel for the fuel cell power generation provides a very competitive cost of hydrogen and electric power, $0.20–0.23/m3 of H2 and $0.196/KWh, respectively. 相似文献
94.
Jianhua Jiang Xi Li Zhonghua Deng Jie Yang Yisheng Zhang Jian Li 《International Journal of Hydrogen Energy》2012
In this paper a systematic method for the development of a constrained generalized predictive control (CGPC) system for a steam reformer is presented. Firstly, a control-oriented dynamic model deriving from physical conservation laws is established and validated by experimental data. Based on the physical model, the control system adopts the Takagi-Sugeno (T-S) fuzzy model to rapidly and accurately predict the reforming temperature. This is identified on-line using the forgetting factor recursive least square (FFRLS) technique. In order to handle input amplitude constraints, the Lagrange Multiplier method is implemented in GPC while the optimal control sequence is obtained by minimizing a multistage objective function. The numerical test results demonstrate that the CGPC control system cannot only achieve rapid and smooth responses, but also possesses excellent disturbance rejection capability which allows it to maintain the reforming temperature during fuel flow rate fluctuations due to SOFC system load variation. 相似文献
95.
论证了合成氨装置一段转化炉对流段烟气余热节能技术改造中的烟气排放温度与余热资源利用效率之间的关系。计算了理论烟气量、理论所需空气量以及烟气的温度、组分、体积流量,核算出烟气的焓值,并与改造前烟气的焓值进行了对比;分析了烟气热量的利用情况。结果表明:实际生产运行的节能量与本文的计算结果基本一致;节能技术改造应遵循在允许的腐蚀限度内,尽可能多地回收烟气热量的原则。 相似文献
96.
97.
《International Journal of Hydrogen Energy》2023,48(74):28733-28746
Compact reformers can be used to produce hydrogen for fuel-cell automobiles. The heat of the mehane seam reforming reaction is provided by methane burning. Generally, conventional burners have been used in combustion chambers. The Computational Fluid Dynamic (CFD) approach was used for the comparison of conventional burners with metal fiber burners and their locations for the first time. The rate of steam reforming reactions and methane combustion reactions were introduced to the CFD model and the Finite Rate/Eddy Dissipation model was used for reactions on the reforming and combustion sections. After validation of the compact reformer results by available experimental data, metal fiber was modeled using the porous-jump interior boundary condition. The results show that the best burner position for the metal fiber is the Bottom (near the catalyst) and for the conventional burner is the Top (far from the catalyst). The results show that the conventional burner in both the Middle and Bottom positions leads to an increase in the reaction zone temperature above 1200 K, which is higher than the catalyst tolerance, but placing a simple burner on the Top of the reactor does not have an out-of-range temperature problem. The hydrogen mass yield for a conventional burner at the Top position is 27.75% relative to methane. Due to the thermal uniformity in the metal fiber burner, the temperature does not exceed the catalyst limitation in the three positions (Top, Middle, and Bottom). The metal fiber burner at the Bottom of the combustion chamber shows the best performance with a hydrogen mass yield of 40.82%. The results indicate that metal fiber burners can distribute the flame more uniformly than conventional burners and increase the available heat for the reformer side. 相似文献
98.
Kantilal Chouhan Shishir Sinha Shashi Kumar Surendra Kumar 《International Journal of Hydrogen Energy》2021,46(53):26809-26824
The paper aims to investigate the steam reforming of biogas in an industrial-scale reformer for hydrogen production. A non-isothermal one dimensional reactor model has been constituted by using mass, momentum and energy balances. The model equations have been solved using MATLAB software. The developed model has been validated with the available modeling studies on industrial steam reforming of methane as well as with the those on lab-scale steam reforming of biogas. It demonstrates excellent agreement with them. Effect of change in biogas compositions on the performance of industrial steam reformer has been investigated in terms of methane conversion, yields of hydrogen and carbon monoxide, product gas compositions, reactor temperature and total pressure. For this, compositions of biogas (CH4/CO2 = 40/60 to 80/20), S/C ratio, reformer feed temperature and heat flux have been varied. Preferable feed conditions to the reformer are total molar feed rate of 21 kmol/h, steam to methane ratio of 4.0, temperature of 973 K and pressure of 25 bar. Under these conditions, industrial reformer fed with biogas, provides methane conversion (93.08–85.65%) and hydrogen yield (1.02–2.28), that are close to thermodynamic equilibrium condition. 相似文献
99.
Minseok Bae Hyungjun Cheon Jiwoo Oh Dongyeon Kim Joongmyeon Bae Sai P. Katikaneni 《International Journal of Hydrogen Energy》2021,46(52):26575-26581
A rapid start-up strategy of a diesel reformer for on-board fuel cell applications was developed by fuel cell integration. With the integration with metal-supported solid oxide fuel cell which has high thermal shock resistance, a simpler and faster start-up protocol of the diesel reformer was obtained compared to that of the independent reformer setup without considering fuel cell integration. A reformer without fuel cell integration showed unstable reactor temperatures during the start-up process, which affects the reforming catalyst durability. By utilizing waste heat from the fuel cell stack, steam required at the diesel autothermal reforming could be stably provided during the start-up process. The developed diesel reformer was thermally sustainable after the initial heat-up process. As a result, the overall start-up time of the reformer after the diesel supply was reduced to 9 min from the diesel supply compared to 22 min without fuel cell integration. 相似文献
100.
《International Journal of Hydrogen Energy》2020,45(38):19880-19890
In this article, the exergy-based modular design is utilized to assess the overall exergy efficiency of the integrated methanol reforming fuel cell (a combination of on-board MeOH-to-H2 processor and proton exchange membrane fuel cell) and improve the 3D modular layout of MeOH-to-H2 processor. It is noted that the preheating system improvement can save installation space as well as increase the overall exergy efficiency. Finally, the 3D modular layout of the new integrated methanol reforming fuel cell (IMRFC) installed into the BMW vehicle chassis demonstrates that this IMRFC vehicle could become a feasible option as compared to the 2016 Toyota Mirai hydrogen fuel cell vehicle. 相似文献