Characteristics Of Fuel Cell Research Articles

Performance Characteristics of a Free-Breathing Polymer Electrolyte Fuel Cell with Various Channel Shapes

This study utilized a small free-breathing fuel cell, with an active area of 4 cm2 (2 cm x 2cm), and channel cathodes with various channel shapes, to experimentally investigate the effect of channel structure on cell performance, to numerically analyze the natural convection air flow in channels, and to compare with the results of performance characterisitics. The results indicated that, compared with a conventional cathode separator with four straight channels (with a width of 3 mm, a depth of 3 mm, and a rib width of 2 mm), cell performance was improved by eliminating some of the channel ribs and increasing the opening ratio, up to a point. A separator with 2 mm square ribs rotated by 45° further improved cell performance. However, when the opening ratio exceeded 72% with a straight center rib of 2 mm width, cell performance leveled off. The analysis results revealed that separators with modified channels promoted natural convection.

Performance Characteristics of a Free-Breathing Polymer Electrolyte Fuel Cell with Various Channel Shapes

This study utilized a small free-breathing fuel cell, with an active area of 4 cm2 (2 cm x 2cm), and channel cathodes with various channel shapes, to experimentally investigate the effect of channel structure on cell performance, to numerically analyze the natural convection air flow in channels, and to compare with the results of performance characterisitics. The results indicated that, compared with a conventional cathode separator with four straight channels (with a width of 3 mm, a depth of 3 mm, and a rib width of 2 mm), cell performance was improved by eliminating some of the channel ribs and increasing the opening ratio, up to a point. A separator with 2 mm square ribs rotated by 45° further improved cell performance. However, when the opening ratio exceeded 72% with a straight center rib of 2 mm width, cell performance leveled off. The analysis results revealed that separators with modified channels promoted natural convection.

The Microbial Fuel Cell Characteristics of the PVA/Chitosan Membrane with Variations of Phosphate Acid and Sodium Alginate Derived from Vegetable Waste

The Microbial Fuel Cell Characteristics of the PVA/Chitosan Membrane with Variations of Phosphate Acid and Sodium Alginate Derived from Vegetable Waste

Characteristics of a Solid Oxide Fuel Cell for the Thermodynamic Modeling of Power Plants

Characteristics of a Solid Oxide Fuel Cell for the Thermodynamic Modeling of Power Plants

Performance Evaluation of an Anode-Supported Solid Oxide Fuel Cell Short-Stack Operating with Different Hydrogen-Natural Gas Blends as Stationary Combined Heat and Power System

One of the most promising characteristics of Solid Oxide Fuel Cells (SOFCs) is the possibility to process a wide variety of fuels with high electrical efficiencies, when compared to other types of fuel cells. Considering the prospected transition of the Natural Gas (NG) grid to hydrogen to decarbonize the gas sector, SOFCs could play a crucial role as efficient and clean stationary Combined Heat and Power (CHP) systems.In this work a 15-cell SOFC short-stack (Anode Supported, cell area 121 cm2) has been analysed experimentally under different compositions resembling possible short-, medium- and long-term gas grid scenarios (100% NG, 67%H2 blend in NG and 100%H2) which have been obtained by a preliminary system-level simulation which takes into account operating conditions of the stack and fine-tuning of the system parameters (e.g. Recirculation Rate RR, once through Fuel Utilization FUot, global Fuel Utilization FUtot) to optimize the overall system-level efficiency. Several tests were run at different temperatures (640-710 °C), Fuel Utilization (FU, 50%-70%) and at current loading (15-30 A - part/full load), characterizing in detail the stack response from an electrochemical (polarization curves and short-term stability tests) and chemical conversion point of view (gas chromatographic analyses in OCV and under load), as well as mapping its performances in stationary conditions (output power and stack-level efficiency). The conversion efficiency has been assessed in detail with different approaches at both stack and cell level, considering both once-through (stack-level) and total (system) FU rates.After having confirmed that the stack performances in reference testing conditions are fully aligned to the stack manufacturer data, confirming the test bench setup validity, the foreseen testing campaign has been carried out showing compatibility of the SOFC stack in the investigated conditions. The results show that from a pure performance point of view the 100%H2 composition obtains highest voltage and power at nominal conditions due to losses of the reformate compositions due to lower OCV values and kinetic behaviour of the chemical reaction chains. Instead, from an efficiency point of view the reformate conditions obtain higher stack-level efficiency (72.02% for the 67%H2+NG; 69.45% for the 100%NG) respect to the 100%H2 compositions (68.61%) due to the lower input fuel calorific value. The comparison of the different efficiency definitions provides further insight on the process and system level. By comparing reference testing conditions before and after the testing campaign it is possible to confirm that no significant degradation has occurred at global stack level in all the compositions. Figure 1

Effect of Water Vapor and Hydrogen Concentration on Power Generation Characteristics of Protonic Ceramic Fuel Cell

The proton and hole conductivities of BaZrO3-based perovskites depend on partial pressures of oxygen and water vapor. These conductivities affect the power generation characteristics of Proton Ceramic Fuel Cells (PCFCs) using the perovskite as an electrolyte. In this study, the effect of humidification conditions on the power generation characteristics of an anode-supported PCFCs was investigated.The configuration of the anode-supported PCFC was La0.6Sr0.4Co0.2Fe0.8O3-δ (LSCF) cathode/BaZr0.8Yb0.2O3-δ(BZYb) electrolyte/Ni-BZYb anode. The diameter of the effective cathode area was approx. 10 mm. The cathode gas composition was fixed at 97% concentration of air and 3% concentration of water vapor. The concentration of water vapor in the anode gas was controlled to be 3-69%. The current density-voltage characteristics and AC impedance were measured by Bio-Logic SP-150.In all water vapor concentration conditions, the cell showed the highest OCV (approximately 1 V) at 3% concentration of water vapor. However, the maximum power density was highest at 30% concentration of water vapor (346 mW/cm2). The highest maximum power density at 30% concentration of water vapor can be explained by the following reason. The OCV values decrease with increasing the concentration of water vapor because of decreasing the concentration of hydrogen. On the other hand, from the results of impedance measurements, the ohmic resistance of the cell decrease with increasing the concentration of water vapor because of increase of proton conductivity of the cell. Thus, the increase of cell voltage by increase of proton conductivity should be higher than the decrease of OCV values.【Acknowledgements】This presentation is the result of the research and development of ultra-efficient proton-conducting ceramic fuel cell devices, JPNP20003, funded by the New Energy and Industrial Technology Development Organization (NEDO), Japan. We would like to express our gratitude to all parties involved.

Experimental evaluation of a 1 kW proton exchange membrane fuel cell with resistive, DC and AC loads

In this communication, an experimental investigation is carried out on a PEM (Proton Exchange Membrane) fuel cell. A small-scale standalone PEM fuel cell system of 1 kW capacity is demonstrated in the present study. The fuel cell is connected to the charge controller, and the charge controller is further connected to the DC and AC loads to study the fuel cell characteristics. A battery bank backup is also provided to account for the stable power output from the fuel cell. The purpose of the study is to determine the fuel cell's performance when operated with resistive, AC, and DC loads (home appliances within the rated power range). The effect of hydrogen flow rates on the power output is also presented in this paper. The DC and AC loads are connected to the fuel cell setup to study the characteristics of the fuel cell. From the study, it can be observed that the performance of the fuel cell is better at higher flow rates of hydrogen. The experimental results showed that the maximum power obtained was 986.8 W at a hydrogen supply rate of 15 LPM. The maximum fuel cell efficiency was found to be 44% at the flow rate of 8 LPM. The charge controller efficiency reported for DC and AC load connections is 94.97% and 96.98%, respectively. The inverter efficiency was observed to increase with the current value, with the maximum value reaching around 98.86%.

Effect of Water Vapor and Hydrogen Concentration on Power Generation Characteristics of Protonic Ceramic Fuel Cell

To investigate the effect of water vapor in the feed gas on the power generation characteristics of PCFCs, the water vapor concentration was changed to 3%, 15%, 30%, and 50%, while the hydrogen concentration in the gas fed to the anode was fixed at 50%. The impedance measurements showed that the ohmic resistance decreased with increasing water vapor concentration, which was attributed to the increase in the proton conductivity of the electrolyte. The measured current density-voltage characteristics showed that the power output increased with increasing water vapor concentration, which was attributed to the decrease in ohmic overvoltage caused by the increase in proton conductivity. In addition, as a more practical condition, the power generation characteristics were measured when the water vapor concentration was varied while the hydrogen concentration was varied in an anode gas consisting only of hydrogen and water vapor.

New Electrogenic Microorganism Citrobacter sp. Isolated from Microbial Fuel Cell and Bacterial Characteristics Determination

The generation of energy through the transformation of polluting waste is a widely explored field and offers advances in green technologies. One of the promising technologies is Microbial Fuel Cells (MFCs). These cells can contain electroactive microorganisms that transform organic waste into electricity by transferring electrons from their metabolism. In this study, a new bacterium capable of producing electricity from the waste of the poultry sector and using copper electrodes, called Av_G1, was identified and isolated. It is phylogenetically related to Citrobacter freundii and Citrobacter Murlinae. This new strain was identified molecularly, biochemically, and phylogenetically; its physiological and morphological characteristics were also studied through a Scanning Electron Microscope (SEM). Biochemical determination was performed using Simmons Citrate Agar, Lysine Iron Medium (L.I.A.), Motility/Ornithine Test, Methyl Red indicator, Enzymes: oxidase and catalase, and Gram stain test. The phylogenetic inference was deduced by bioinformatics tools (MEGA X, JalView, Clustal Omega) and the genetic databases The Ribosomal Database Project—RDP and the National Center for Biotechnology Information (NCBI). A maximum current potential of 0.645 V, a maximum current density of 168.72 ± 14.07 mA/m2, and a power density of 31.05 mW/m2 were recorded. During the monitoring, the physicochemical parameters were taken: pH, Oxide Reduction Potential (ORP), Dissolved Oxygen (DO), conductivity, Total Solids (TDS), and average temperature were recorded. Therefore, the present study shows a new Gram-negative electrogenic bacterium, which can be used for electrochemical processes and applied in MFC with copper electrodes.

Influences of Flow Channel on Electrochemical Characteristics of Polymer Electrolyte Fuel Cells Humidified with NaCl Contained H2O

In this study, the effects of flow field types on the electrochemical properties of polymer electrolyte membrane fuel cells (PEMFCs) humidified with NaCl solution are systematically investigated. The parallel flow field and serpentine flow field were used to investigate the PEMFCs. Long-term stability was evaluated for 20 h using chronoamperometry. Fuel cells with both parallel and serpentine flow fields showed a decrease in performance because of the NaCl solution. Interestingly, the PEMFC with the serpentine flow field showed significantly more severe degradation during long-term stability evaluation compared to the fuel cell with the parallel flow field. Electrochemical impedance spectroscopy analysis showed that a significant increase in faradaic resistance caused the degradation of the performance. After long-term stability examinations, regenerations of fuel cells were performed with deionized water at a constant voltage (0.4 V). After the regeneration, the performance of the fuel cells with the serpentine flow field was improved more (52.96%) than the PEMFC with the parallel flow field (1.22%).

The development of sulfonated polyether ether ketone (sPEEK) and titanium silicon oxide (TiSiO4) composite membranes for DMFC applications

This work aims to develop composite membranes based sPEEK polymer matrix with TiSiO4 for direct methanol fuel cell (DMFC) applications. The sPEEK having 53% of degree of sulfonation (DS) was preferred to avoid dissolution and high-swelling problems of the polymer matrix at the operating conditions. The various content of TiSiO4, prepared by the calcination reaction of TiO2 and SiO2 nano-powders, was placed into the sPEEK matrix using the solution-casting method. The thermal and physicochemical properties of the composite membranes were characterized. AC impedance spectroscopy and methanol diffusivity measurements were conducted to determine the fuel cell characteristics of the membranes. The composite sPEEK membrane with 2.5 wt% TiSiO4 performed the highest single-cell DMFC test performance compared with sPEEK and Nafion™ 117 membranes. It can be concluded that the composite sPEEK membranes with TiSiO4 can be promising and low-cost alternative membranes for DMFC applications.

Effect of reduced graphene oxide (rGO) in chitosan/Pahae natural zeolite-based polymer electrolyte membranes for direct methanol fuel cell (DMFC) applications

The use of electrolyte membranes for fuel cell applications has grown rapidly, and one of the materials often developed is chitosan. In this study, polymer electrolyte membranes were successfully produced using chitosan and Pahae natural zeolite with the addition of various reduced Graphene Oxide (rGO) concentrations. Furthermore, water and methanol uptake values, methanol permeability, ion exchange capacity, and proton conductivity were the basic characteristics of Direct Methanol Fuel Cells (DMFC) applications. The optimum water uptake value was observed in the CS/PNZ/rGO 2.0 % membrane at 294.5 %. This value increased with the addition of rGO concentration and is in line with the increasing ion exchange capacity. The CS/PNZ/rGO 2.0 % membrane has the optimum ion exchange capacity with a value of 0.8121 mmol/g. Meanwhile, the membrane permeability value tends to decrease with increasing rGO composition at each variation of methanol concentration. The proton conductivity value also increased along with rGO concentration, and the highest value was found in CS/PNZ/rGO 2.0 % at 6.777×10−6 S/cm. Based on the results, high ion exchange capacity, low permeability, and high proton conductivity indicate that CS/PNZ/rGO-based polymer electrolyte membranes can be used in Direct Methanol Fuel Cells (DMFC) applications.

Characteristics of fuel cells under static and dynamic conditions

Modern internal combustion powertrains are the main source of propulsion for on-road and non-road vehicles. However, they are increasingly being replaced by electric or fuel cell-equipped alternative propulsion systems. The article presents a study of fuel cell characteristics operating under both static and dynamic conditions, with a 1.2 kW fuel cell set with a voltage converter and lead-acid batteries. In the conducted tests, the fuel cell stack's maximum efficiency reached 65%. Load tests (static and dynamic) have indicated higher fuel cell efficiencies when using hybrid operation with a DC/DC converter and battery.

Effects of Humidification with NaCl Solution Mist on Electrochemical Characteristics of Polymer Electrolyte Membrane Fuel Cells

This study examined the effects of mist generated from NaCl solution on the electrochemical properties of polymer electrolyte membrane fuel cells. Mist-containing Na+ and Cl- ions were generated using a custom-made mist generator. The current density-voltage-power density curves and electrochemical impedance spectroscopy of fuel cells were systematically achieved. Furthermore, long-term stability experiments were carried out using chronoamperometry mode for 20 h with deionized water and NaCl solution. After the chronoamperometry measurement, the regeneration of fuel cells was performed with deionized water. The effects of regeneration methods on the performance of the fuel cell were evaluated. Due to the internally produced H2O, constant voltage regeneration was more effective than open circuit voltage regeneration.

Performance Characteristics of a Direct Ammonia Fuel Cell with an Anion Exchange Membrane

In this work, a direct ammonia fuel cell, which consists of an anion exchange membrane and commercially available PtRu/C and Pd/C catalysts at the anode and cathode, respectively, is developed. Experimental results demonstrate that the direct ammonia fuel cell exhibits a peak power density of 20.7 mW cm–2 and an open-circuit voltage of 0.67 V at 95 °C when fed with 3.0 M ammonia and 3.0 M KOH. Besides, the durability test results reveal that the developed direct ammonia fuel cell can maintain stable operation for more than 25 h. In addition, the effects of operating parameters, such as the concentrations of ammonia and KOH, flow rates of anolyte and oxygen, and operating temperatures on the cell performance, are experimentally examined. A higher KOH concentration is observed to increase the cell voltage by enhancing the kinetics of ammonia oxidation, which is facilitated by the higher concentration of OH– in the catalyst layer. However, increasing the KOH concentration leads to higher internal resistance in the cell as a result of the increased viscosity of the anolyte. Besides, the analysis of results suggests that a moderate flow rate of both anolyte and gaseous oxygen can also enhance the cell performance by reducing ammonia crossover and preventing membrane dehydration, respectively. Moreover, increasing the operating temperature of the cell also promotes the kinetics of the electrochemical reactions at the catalyst layers, which is also associated with an enhanced mass transfer within the electrodes. In summary, a direct ammonia fuel cell, using an anion exchange membrane, with relatively high performance has been developed. The study provides insights into the performance-enhancing strategies, via operating conditions, toward the further development of the cell.

Cover Feature: Flow Channel Architecture and Diffusion Characteristics of Nonenzymatic Electrochemical Glucose Fuel Cells with Proton Exchange Membrane (ChemElectroChem 20/2022)

Cover Feature: Flow Channel Architecture and Diffusion Characteristics of Nonenzymatic Electrochemical Glucose Fuel Cells with Proton Exchange Membrane (ChemElectroChem 20/2022)

Investigation of PEM Fuel Cell Characteristics in Steady and Dynamic Operation Modes

The article is devoted to the problem of proton-exchange membrane fuel cells (PEMFCs) integration into power supply systems. A hybrid energy complex (HEC) based on PEMFCs and lithium iron phosphate batteries can be used as a reliable energy source. It is necessary to properly determine the PEMFC characteristics in order to develop a PEMFC-based HEC prototype and its control algorithms. This paper presents a 1 kW PEMFC’s test results in steady and dynamic modes. The dependences of the average hydrogen consumption per 1 min, the volume of hydrogen for the generation of 1 kWh, the PEMFC efficiency on the load current were obtained and an analysis of these dependences for steady operation modes was performed. A range of load changes beyond which the efficiency of the PEMFC significantly decreased and it was recommended to switch to the joint operation of the PEMFCs and batteries (or only batteries) was established. Diagrams of the PEMFC output voltage during the dynamic changes in loads are presented and an analysis of transient response characteristics was carried out. The air supply fans were found to affect the performance of PEMFCs.

Power Generation Characteristics of Polymer Electrolyte Fuel Cells Using Carbon Nanowalls as Catalyst Support Material

We evaluated the power generation characteristics of a polymer electrolyte fuel cell (PEFC) composed of Pt-supported carbon nanowalls (CNWs) and a microporous layer (MPL) of carbon black on carbon paper (CP) as catalyst support materials. CNWs, standing vertically on highly crystallizing graphene sheets, were synthesized on an MPL/CP by plasma-enhanced chemical vapor deposition (PECVD) using inductively coupled plasma (ICP). Pt nanoparticles were supported on the CNW surface using the liquid-phase reduction method. The three types of voltage loss, namely those due to activated polarization, resistance polarization, and diffusion polarization, are discussed for the power generation characteristics of the PEFC using the Pt/CNWs/MPL/CP. The relationship between the height or gap area of the CNWs and the voltage loss of the PEFC is demonstrated, whereby the CNW height increased with the extension of growth time. The three-phase interface area increased with the increase in the CNW height, resulting in mitigation of the loss due to activated polarization. The gap area of the CNWs varied when changing the CH4/H2 gas ratio. The loss due to diffusion polarization was reduced by enlarging the gap area, due to the increased diffusion of fuel gas and discharge of water. The secondary growth of the CNWs caused the three-phase interface area to decrease as a result of platinum aggregation, impedance of the supply of ionomer dispersion solution to the bottom of the CNWs, and inhibition of fuel gas and water diffusion, which led to the loss of activated and diffuse polarizations. The voltage losses can be mitigated by increasing the height of CNWs while avoiding secondary growth.

Control of hybrid DC/AC microgrid system employing fuel cell and solar photovoltaic sources using grey wolf optimization

Abstract The outcome of this study is to improve and enhance the power quality of the hybrid DC/AC microgrid (MG). The photovoltaic (PV) system and the proton exchange membrane fuel cell (PEMFC) are used as renewable energy sources to deliver the optimum active power to the utility grid. The MG system based on the PV system, PEMFC and voltage source inverter is modelled mathematically. Also, the maximum power point tracking (MPPT)-based grey wolf optimization (GWO) is used to increase the PV module efficiency and enhance performance. Also, to improve the PEMFC performance, a digital proportional-integral controller is used to control the PEMFC circuit. The proposed inverter is controlled using synchronous reference frame theory, called the direct-quadrature (dq) control method. Hence, the performance of the proposed MG system is tested using MATLAB® for various weather and loading conditions. From the simulation results, the proposed MG system can deliver and absorb an active power based on the PV and fuel cell characteristics. As a result, the hybrid DC/AC MG is enhanced in terms of stabilization of the DC-bus voltage. Also, the power quality of the MG is improved using GWO optimization based on MPPT. Finally, good results are achieved using GWO in terms of the total harmonic distortion of the output current of 2.3% and higher efficiency of 98.9%.

Flow Channel Architecture and Diffusion Characteristics of Nonenzymatic Electrochemical Glucose Fuel Cells with Proton Exchange Membrane

A nonenzymatic glucose fuel cell directly oxidizes glucose to gluconic acid as a Pt-based abiotic catalyst in a proton exchange membrane environment and has various advantages (e.g., biocompatibility, chemical stability, high ionic conductivity). We report the permeability of a less hydrophobic diffusion layer for three flow-field designs (serpentine, interdigitated, and parallel). In all cases, as the channel width of the flow path increases, the power density increases and the Ohmic resistance decreases. The serpentine shape (channel and rib widths: 1.5 and 0.5 mm, respectively) exhibits remarkable maximum power and current densities (cell voltage: 60 mV) of 103.4 μW cm -2 and 1,273 μA cm -2 compared to those of the parallel (46.5 μW cm -2 , 683 μA cm -2 ) and interdigitated (74.0 μW cm -2 , 878 μA cm -2 ) shapes, respectively. Furthermore, permeability and performance analyses according to the single-cell temperature, glucose concentration, and flow rate changes provide various perspectives on glucose fuel cells.