共查询到20条相似文献,搜索用时 15 毫秒
1.
Cold start from subzero temperature is one of the key barriers, which prevents proton exchange membrane fuel cell (PEMFC) from further commercialization. In this paper, we have applied the printed circuit board (PCB) technology to study the current density distributions of PEMFC and optimized the technology under rapid cold start. The results show that increasing the initial load, and the setup temperature can help to lower the cold start time and achieve rapid warm-up of PEMFC. The cell can be rapidly cold started for 10 s at −5 °C and 55 s at −10 °C under 0.2 V operation condition, but it failed at −15 °C and −20 °C. The inlet region and middle region produce half of the total current before the overall peak current density is reached, which is important for the successful cold start. Based on these characteristics, we optimized the rapid cold start strategy by co-operation of hot reactant gas and waste heat generation of PEMFC. It becomes possible to start up the PEMFC at temperatures down to −20 °C with about 20 min. 相似文献
2.
Air-breathing miniature planar stack using the flexible printed circuit board as a current collector
Sung Han Kim Hye Yeon Cha Craig M. Miesse Jae Hyuk Jang Yong Soo Oh Suk Won Cha 《International Journal of Hydrogen Energy》2009
To maximize power density, the volume of a fuel cell stack should be reduced by miniaturizing the stack components. In this study, thin flexible printed circuit board was utilized as a current collector in order to reduce an air-breathing monopolar stack's volume. Also, the effects of varying the geometry and opening ratios of the ports to the cathode on stack performance were evaluated in order to determine the optimal cathode structure. Use of the thin current collector and cathode port optimization resulted in an output of 3.5 W from an 18 cm3 stack (power density of 350 mW/cm2). The effects of orientation under passive air-breathing operation were determined to be nearly negligible. All data was measured at ambient pressure and temperature, baseline conditions for mobile fuel cell intended for use in consumer electronics. 相似文献
3.
Computational study of forced air-convection in open-cathode polymer electrolyte fuel cell stacks 总被引:1,自引:0,他引:1
A mathematical model for a polymer electrolyte fuel cell (PEFC) stack with an open-cathode manifold, where a fan provides the oxidant as well as cooling, is derived and studied. In short, the model considers two-phase flow and conservation of mass, momentum, species and energy in the ambient and PEFC stack, as well as conservation of charge and a phenomenological membrane and agglomerate model for the PEFC stack. The fan is resolved as an interfacial condition with a polynomial expression for the static pressure increase over the fan as a function of the fan velocity. The results suggest that there is strong correlation between fan power rating, the height of cathode flow-field and stack performance. Further, the placement of the fan - either in blowing or suction mode - does not give rise to a discernable difference in stack performance for the flow-field considered (metal mesh). Finally, it is noted that the model can be extended to incorporate other types of flow-fields and, most importantly, be employed for design and optimization of forced air-convection open-cathode PEFC stacks and adjacent fans. 相似文献
4.
The analysis of the electrochemical behaviour of polymer electrolyte fuel cells (PEFC) both in time and frequency domain requires appropriate impedance models. Simple impedance models with lumped parameters as resistances and capacitances or Warburg impedances do have limitations: often the validity is limited to a certain frequency range, effects at very low or very high frequencies can not be described properly. 相似文献
5.
The dynamic behavior of polymer electrolyte fuel cells was investigated experimentally at sudden load change conditions. The present study mainly focused on the variation of membrane hydration due to self-humidification. Steady-state results for various temperatures and humidities were used as the basic data for the analysis of dynamic behavior. Electrochemical impedance spectroscopy (EIS) showed that the ohmic resistance was reduced with the increase of humidity and current while the total polarization resistance including the mass transfer effect showed various trends according to cell temperature. The dynamic behavior of the cells was measured with time. The current increment just after an abrupt voltage reduction jumped to a certain level and then increased gradually, showing a logarithmic-shape curve. The stabilization time to steady-state was determined by using the curve-fitted lines representing the variation of the current increment at each operating condition. The stabilization time showed various trends according to cell temperature, humidity, and voltage range. 相似文献
6.
A miniature air breathing compact direct formic acid fuel cell (DFAFC), with gold covered printed circuit board (PCB) as current collectors and back boards, is designed, fabricated and evaluated. Effects of formic acid concentration and catalyst loading (anodic palladium loading and cathodic platinum loading) on the cell performance are investigated and optimized fuel concentration and catalyst loading are obtained based on experimental results. A maximum power density of 19.6 mW cm−2 is achieved at room temperature with passive operational mode when 5.0 M formic acid is fed and 1 mg cm−2 catalyst at both electrodes is used. The home-made DFAFC also displays good long-term stability at constant current density. 相似文献
7.
Electrochemical impedance spectroscopy (EIS) was employed for in situ diagnosis for polymer electrolyte membrane fuel cells during operation. First, EIS was measured as a function of operation parameters such as applied current density, gas flow rates and gas humidification temperature. The resistance that correlated with conductivity of the membrane and the contact resistance between bipolar plate and gas diffusion layer (GDL) was set as Rm in the assumed equivalent circuit. The charge transfer resistances were considered for cathode (Rct(C)). The value of Rct(C) was sensitive to the parameters that affected cell voltage. Additionally, the diffusion resistance (Rd) was ascribed to the effect of oxygen supply and drainage of generated water. Second, the influence of corrosion of type 430 stainless steel bipolar plates was evaluated by EIS method during operation. Corrosion of the stainless steel bipolar plates resulted in an increase in the value of Rd. 相似文献
8.
Thomas Kadyk Richard Hanke-Rauschenbach Kai Sundmacher 《International Journal of Hydrogen Energy》2012
Dehydration phenomena in a PEM fuel cell were investigated by nonlinear frequency response analysis (NFRA) in a differential H2/H2 cell. The linear H1,0 spectra, which are equal to classic EIS spectra, showed not only an increase of the membrane resistance but also an increase of the anode reaction resistance, caused by dehydration leading to the decrease of the protonic conductivity of the polymer network in the catalyst layer. With this, active sites with long protonic pathes to the membrane become inactive. In order to further clarify this effect, modelling work was used. Therefore, proton transport was incorporated into an existing model of a differential H2/H2 cell. Finally, the key features of NFRA spectra under dehydration and CO poisoning are compared in order to discuss the suitability of NFRA for unambiguous diagnosis of PEMFC. It can be seen that while the linear spectrum is not sufficient to distinguish between both cases, the second order frequency response functions can be used for discrimination. 相似文献
9.
Jincheol Kim Dong-Min Kim Sung-Yug Kim Suk Woo Nam Taegyu Kim 《International Journal of Hydrogen Energy》2014
In the present study, a short circuit controller for use in the humidification of polymer electrolyte membrane fuel cells was developed for unmanned aerial vehicles (UAVs). Fuel cells (FCs) require an external humidifier to avoid drying up. Particularly in UAV applications, humidity control is more important because the boiling point of water decreases with increase in flight altitude. In this study, overcurrent was generated by short-circuiting an FC to humidify the electrolyte membrane and improve the electric power output. An FC controller incorporating a short circuit unit was developed, and a battery was hybridized with the FC to compensate the power when the latter was short-circuited. The performance of the FC was evaluated for the interval (period) and duration of short circuit. Using this method, the power output was improved by 16% when short circuit control was operated at the optimal condition. 相似文献
10.
Jeawoo Jung Young-Hoon Chung Hee-Young Park Jonghee Han Hyoung-Juhn Kim Dirk Henkensmeier Sung Jong Yoo Jin Young Kim So Young Lee Kwang Ho Song Hyun S. Park Jong Hyun Jang 《International Journal of Hydrogen Energy》2018,43(32):15457-15465
The effects of varying the applied voltage and relative humidity of feed gases in degradation tests of polymer electrolyte membrane fuel cells (PEMFCs) were analyzed using electrochemical impedance spectroscopy (EIS). A transmission line model that considers the proton-transport resistance in the cathode catalyst layer was used to analyze impedance spectra obtained from degraded PEMFCs. As the applied cell voltage was increased from 1.3 to 1.5 V to induce accelerated degradation, the cell performance decayed significantly due to increased charge- and proton-transfer resistance. The PEMFC degradation was more pronounce at higher relative humidity (RH), i.e. 100% RH, as compared with that observed under 50% RH. Furthermore, changes in the charge transfer resistance of the electrode accompanied changes in the ionic conductivity in the PEMFC catalyst layer. Although the initial ionic and charge-transfer resistances in the catalyst layer were lower under higher RH conditions, the impedance results indicated that the performance degradation was more significant at higher water contents in the electrode due to the consequential carbon corrosion, especially when higher voltages, i.e. 1.5 V, were applied to the PEMFC single cell. 相似文献
11.
I. Dedigama P. Angeli K. Ayers J.B. Robinson P.R. Shearing D. Tsaoulidis D.J.L. Brett 《International Journal of Hydrogen Energy》2014
An optically transparent polymer electrolyte membrane (PEM) water electrolysis cell was studied using a high-speed camera, thermal imaging and electrochemical impedance spectroscopy to examine the relationship between flow and electrochemical performance. The flow regime spans bubble and slug flow, depending on the rate of gas formation (current density) and water feed rate. Electrochemical impedance spectroscopy (EIS) shows that there is a reduction in mass transport limitation associated with the transition to slug flow. 相似文献
12.
Coated aluminum bipolar plates demonstrate better mechanical strength, ease of manufacturability, and lower interfacial contact resistance (ICR) than graphite composite plates in polymer electrolyte membrane (PEM) fuel cell applications. In this study, coated aluminum and graphite composite bipolar plates were installed in separate single PEM fuel cells and tested under normal operating conditions and cyclic loading. After 1000 h of operation, samples of both the bipolar plates and the membrane electrode assembly (MEA) were collected from both the cathode and the anode sides of the cell and characterized to examine the stability and integrity of the plate coating and evaluate possible changes of the ionic conductivity of the membrane due any electrochemical reaction with the coating material. Scanning electron microscope (SEM) and energy dispersive X-ray (EDX) analysis were performed on the land and valley surfaces of the reactant flow fields at both the anode and the cathode sides of the bipolar plates. The measurements were superimposed on the reference to identify possible zones of anomalies for the purpose of conducting focused studies in these locations. The X-ray diffraction (XRD) analysis of samples scraped from the anode and cathode electrodes of the MEA showed the tendency for catalyst growth that could result in power degradation. Samples of the by-product water produced during the single fuel cell operation were also collected and tested for the existence of chromium, nickel, carbon, iron, sulfur and aluminum using mass spectroscopy techniques. The EDX measurements indicated the possibility of dissociation and dissolution of nickel chrome that was used as the binder for the carbide-based corrosion-resistant coating with the aluminum substrate. 相似文献
13.
Mehmet Ozan Ozdemir Md Aman Uddin Selvarani Ganesan Ugur Pasaogullari William P. Collins Leonard Bonville Trent Molter 《International Journal of Hydrogen Energy》2017,42(41):26068-26083
Regular maintenance/cleaning of fuel pipeline and system hardware is an essential requirement in fuel cell operation to prevent contamination. An experimental and analytical study is performed to aid the selection of appropriate cleansers to be used as cleaning agents in polymer electrolyte fuel cell (PEFC). Screening tests for several cleansers are carried out during the injection of samples into the PEFC cathode inlet. One proper agent (naphtha) has shown a fully recoverable and minimal effect on the fuel cell performance and as such is determined as the best cleansing agent. Unlike other samples, naphtha does not contain any metallic components such as sodium or potassium in its composition. Furthermore, PEFC can still operate at ~0.4 V at constant current (1 A/cm2) even with a considerable flow rate (250 μl/min) of the selected cleanser. Detailed analytical analysis of this cleanser is provided by curve fitting the electrochemical impedance spectroscopy data, and evaluation of binary gas diffusion coefficients. It is indicated that performance loss during naphtha exposure is mainly due to the adsorption of contaminants on active Pt sites and an increase in mass transfer resistance. 相似文献
14.
Application of thermal imaging to validate a heat transfer model for polymer electrolyte fuel cells 总被引:1,自引:0,他引:1
Heat management in polymer electrolyte membrane fuel cells (PEMFCs) plays a vital role in stack performance and durability, and overall system efficiency. A computational model assembled by the authors has been used to study the heat generated and distributed in single-cell and two-cell PEMFC stacks, with a focus on temperature variation on the external surfaces of the stack under different heat loads. 相似文献
15.
An efficient controller is greatly important for the quick load-following response of solid oxide fuel cell (SOFC) power systems, which is vital for the fuel utilization and the life of the stack. To design such a controller, an accurate dynamic model of SOFC electrical characteristics is critical. Here an integer order dynamic model is established by a transient equivalent circuit, and then a fractional order dynamic model is done in the perspective of the fractional derivatives theory. The parameters of the dynamic models then are optimized via genetic algorithms according to electrochemical impedance spectroscopy (EIS) experimental data. Finally, the dynamic response experiments from the models are studied. The results show that the fractional order dynamic model has higher accuracy for representing the dynamics of the SOFC electrical characteristics, which lays a solid foundation for the controller based on the accurate model. 相似文献
16.
End plate is one of the main components of the proton exchange membrane (PEM) fuel cells. The major role of the end plate is providing uniform pressure distribution between various components of the fuel cell (bipolar plates, etc.) and consequently reducing contact resistance between them. In this study a procedure for design of end plate has been developed. At first a suitable material was selected using various criteria. Then a finite element (FE) analysis was accomplished to analyze end plate deflections and get its optimized thickness. After fabricating the end plates, a single cell was assembled and electrochemical impedance spectroscopy (EIS) tests were carried out to ensure their good operation. A 5 kW fuel cell assembled with these end plates was tested at different operating conditions. The test results show an appropriate assembly pressure distribution inside the stack which indicates good performance of the designed end plates. 相似文献
17.
Mozhdeh Noorkami James B. Robinson Quentin Meyer Oluwamayowa A. Obeisun Eric S. Fraga Tobias Reisch Paul R. Shearing Daniel J.L. Brett 《International Journal of Hydrogen Energy》2014
The temperature of operation is a key parameter in determining the performance and durability of a polymer electrolyte fuel cell (PEFC). Controlling temperature and understanding its distribution and dynamic response is vital for effective operation and design of better systems. The sensitivity to temperature means that uncertainty in this parameter leads to variable response and can mask other factors affecting performance. It is important to be able to determine the impact of temperature uncertainly and quantify how much PEFC operation is influenced under different operating conditions. Here, a simple lumped mathematical model is used to describe PEFC performance under temperature uncertainty. An analytical approach gives a measure of the sensitivity of performance to temperature at different nominal operating temperatures and electrical loadings. Whereas a statistical approach, using Monte Carlo stochastic sampling, provides a ‘probability map’ of PEFC polarisation behaviour. As such, a polarisation ‘area’ or ‘band’ is considered as opposed to a polarisation ‘curve’. Results show that temperature variation has the greatest effect at higher currents and lower nominal operating temperatures. Thermal imaging of a commercial air-cooled stack is included to illustrate the temporal and spatial temperature variation experienced in real systems. 相似文献
18.
Oh Joong KwonMoo Seong Kang Sang Hyun AhnInsoo Choi Kang Uk LeeJee Hoon Jeong In-Su HanJae Chun Yang Jae Jeong Kim 《International Journal of Hydrogen Energy》2011,36(16):9799-9804
The design of a flow field channel of a polymer electrolyte membrane fuel cell (PEMFC) was investigated by computational fluid dynamic (CFD) simulation and in-situ three-channel impedance spectroscopy. To investigate the efficiency of the in-situ three-channel impedance spectroscopy method, it was adopted with a heterogeneous stack, which was composed according to three different types of flow field design. The in-situ three-channel method proved its validity by showing corresponding result with that obtained from the experiments and CFD simulation at the same experimental condition. This study demonstrates that a heterogeneous stack and in-situ three-channel impedance spectroscopy are powerful tools for predicting and analyzing the performance of a fuel cell stack. 相似文献
19.
Dongmei Yao Ting-Chu Jao Weiqi Zhang Li Xu Lei Xing Qiang Ma Qian Xu Huaming Li Sivakumar Pasupathi Huaneng Su 《International Journal of Hydrogen Energy》2018,43(45):21006-21016
Ex-situ electrochemical characterization techniques could significantly alter or misrepresent the materials of high temperature polymer electrolyte membrane fuel cell (HT-PEMFC) to the point where they are not reflective of their conditions during operation, resulting in difficulties in obtaining realistic fuel cell durability. To minimize this disturbance, we proposed an in-situ low-invasive technique of electrochemical impedance spectroscopy (EIS), combining with polarization curve and Tafel slope analysis, to investigate the performance degradation of HT-PEMFC. The membrane electrode assemblies (MEAs) used in the HT-PEMFC were lab-made but with commercial catalyst and poly(2,5-benzimidazole) (ABPBI) membrane. Two common test modes, i.e. steady-state operation and dynamic-state operation, were employed to mimic practical HT-PEMFC operation. By examining the changes of electrochemical properties of the HT-PEMFC under steady- or dynamic-state operation, the main mechanism for the performance degradation can be determined. The results from the study suggests that a high cell performance decay rate cannot be directly attributed to materials degradation, especially in a short-term steady-state operation. In contrast, the change of Tafel slope can be seen as a clear indicator to determine the extent of catalyst degradation of HT-PEMFC, no matter which test protocol was applied. Post-analysis of TEM on the catalysts before and after tests further confirmed the main mechanism for the performance losses of the HT-PEMFCs underwent two test protocols, while acid loss and membrane degradation were considered to be negligible during the short-term tests. 相似文献
20.
Chun YangJinhai Wang Xiaofeng Xie Shubo WangZongqiang Mao Hairen Wang 《International Journal of Hydrogen Energy》2012,37(1):867-872
Corrosion resistance performance of SS316L treated by passivation solution was investigated in a simulated environment of the passive direct methanol fuel cell (DMFC). Electrochemical impedance spectroscopic (EIS) test showed that polarization resistance of untreated and treated SS316L were 1191 Ω cm2 and 9335 Ω cm2, respectively. The above result agreed with the Tafel slope analysis of potentiodynamic polarization curves. Comparing the untreated and treated SS316L in the simulated environment of DMFC anode working conditions, it was observed that the corrosion current density of treated SS316L as estimated by 4000 s potentiostatic test reduced from 38.7 μA cm−2 to 0.297 μA cm−2, meanwhile, the current densities of untreated and treated SS316L in cathode working conditions were 3.87 μA cm−2 and 0.223 μA cm−2, respectively. It indicated that the treated SS316L should be suitable in both anode and cathode environment of passive DMFCs. The treated SS316L bipolar plates have been assembled in a passive single fuel cell. A peak power density of 1.18 mW cm−2 was achieved with 1 M methanol at ambient temperature. 相似文献