Proton Electrolyte Membrane Fuel Cell Research Articles

Research on Energy Management Strategy of Fuel Cell Vehicle Based on Multi-Dimensional Dynamic Programming

The powertrain of a fuel cell vehicle typically consists of two energy sources: a proton electrolyte membrane fuel cell (PEMFC) stack and a battery package. In this paper, multi-dimensional dynamic programming (MDDP) is used to solve the energy management strategy (EMS) of fuel cell hybrid powertrain. This study built a fuel cell hybrid powertrain model, in which the battery model is built based on the Thevenin equivalent circuit. In order to improve the calculating efficiency and maintain the accuracy of the algorithm, the state variables in each stage are divided into primary and secondary. In the reverse solution process, the corresponding relationship between the multi state variables grid and the optimal cumulative function has been changed from three-dimensional to two-dimensional. The EMS based on MDDP is applied to component sizing of a commercial vehicle. Simulations were conducted using MATLAB under the C-WTVC working condition. By analyzing the fuel economy and system durability, the optimal component combination of comprehensive performance is obtained. Compared with the EMS based on dynamic programming (DP), the proposed method effectively improves the calculation accuracy: the hydrogen consumption can be reduced by 3.10%, and the durability of the fuel cell and battery can be improved by 1.08% and 0.13%, respectively.

The Characteristics of Hybrid Al2O3:SiO2 Nanofluids in Cooling Plate of PEMFC

A Proton Electrolyte Membrane fuel cells (PEMFC) is considered to be a viable alternatives to Internal Combustion Engines (ICEs) in automotive applications due to the key advantages in thermal management system. The main duty of thermal management system is to maintain the desirable temperature, with a uniform temperature distribution across the stack and.its.individual membranes. In this paper, the thermal enhancement of a PEMFC cooling plate was analysed and presented. The hybrid Al₂O₃:SiO₂ was used as coolant in distributor cooling plate. The study focuses on water based 0.5% volume concentration of single Al₂O₃ , single SiO₂ nanofluids, hybrid Al₂O₃:SiO nanofluids with mixture ratio of 10:90, 20:80, 50:50, 60:40 and 90:10. The effect of different ratios of nanofluids to heat transfer enhancement and fluid flow in Reynold number range of 400 to 2000 was observed. A 3D computational fluid dynamic (CFD) was developed based on distributor cooling plates using Ansys 16.0. Positive heat transfer enhancement was obtained where the 10:90 Al₂O₃:SiO₂ nanofluids has the highest heat transfer coefficient as compared to other nanofluids used. However, all nanofluids experienced higher pressure drop. Therefore, the advantage ratio was used to analyze the effect of both heat transfer enhancements and pressure drop demerits for nanofluids adoption. The results concluded that 10:90 Al₂O₃:SiO₂ hybrid nanofluid is the most feasible candidate up to fluid flow of Re1000. The positive results implied that hybrid Al₂O₃:SiO₂ nanofluids do improve the single nanofluids behaviour and has a better potential for future applications in PEMFC thermal management.

Unraveling Dispersion Characteristics of Electrocatalyst Inks for Proton Exchange Membrane Fuel Cells

The membrane electrode assembly (MEA) forms the core of the proton electrolyte membrane fuel cell (PEMFC).1 Catalyst layers (CLs) that are home to the electrochemical reactions are an active component of an MEA. CLs are typically manufactured by various dispersion-coating methods where a catalyst ink is applied onto a membrane. Controlling the CL preparation methods to obtain the ideal microstructure and morphology of the CL is of utmost importance, where tailoring of inks represents a key aspect.2 For the large-scale manufacturing of PEMFCs, obtaining favorable dispersion characteristics of inks is indispensable.In this study, we propose new tools to study dispersion state and stability based on analytical centrifugation (AC) in order to facilitate a knowledge-based approach for ink development. The dispersion behavior of catalyst inks prepared by different processing techniques were compared. The effects of processing methods were characterized by the proposed techniques and by rheological measurements, structural characterization of diluted inks was carried out by electron microscopy.New concepts, S score and stability trajectory 3 were introduced for a time-resolved assessment of inks in their native state by means of AC. S score is a quantitative number calculated from the transmission data recorded by AC. The time-series of S scores results in a stability trajectory that defines the degree of heterogeneity in the dispersion. The findings were validated via a direct visualization technique namely, transmittogram4 and correlated with flow behavior and structural properties. References V. Mehta and J. S. Cooper, J. Power Sources, 114, 32–53 (2003).M. Bredol et al., J. Power Sources, 402, 15–23 (2018).S. Bapat et al., ChemRxiv, preprint, DOI: 10.26434/chemrxiv.13125401.v3 (2021).S. Bapat and D. Segets, ACS Appl. Nanomater., 3, 7384–7391 (2020).

Investigation of liquid water behaviors inside a PEMFC cathode with a leaf-like biomimetic flow field design based on Murray’s Law

ABSTRACT Water management is the key to further improvement in the performance and durability of proton electrolyte membrane fuel cells (PEMFCs). The flow field inside the bipolar plates has a major role in managing the flooding process. Biomimetic flow field designs have been capturing the attention of researchers for their promising characteristics including uniform flow distribution and low pressure drop. Therefore, this study investigates liquid water behaviors inside a leaf-like biomimetic flow field design based on Murray’s Law using at the cathode of a PEMFC. The investigation is conducted using a computational simulation method utilizing the commercial software Ansys Fluent, in which the volume of fluid method is implemented for the three-dimensional, two-phase, unsteady flow simulation with the application of a dynamic contact angle model. The results are the general water transport process, the velocity, and pressure distribution inside the leaf-like biomimetic flow field design based on Murray’s Law.

Heat Transfer and Pressure Drop Characteristics of Hybrid Al2O3-SiO2

The emergence of Proton Electrolyte Membrane Fuel Cell (PEMFC) is seen as one of the greener alternatives to internal combustion engine (ICE) in automotive industry nowadays. However, the sensitivity of a PEMFC membrane needs to be further improved for the optimum performance. In this study, single and hybrid nanofluids are used as an alternative coolant in a single channel of PEMFC. The study was conducted in a channel with the adoption of single and hybrid nanofluids to observe the effect of the heat transfer and pressure drop in the set up. A heater pad was kept at constant heat load of 100 W, reflecting the actual heat load of a single cell. The study focuses on 0.5% volume concentration for single and hybrid nanofluids of Al2O3 and SiO2 in water. The numerical study was conducted via ANSYS FLUENT 16.0. The 0.5% hybrid Al2O3:SiO2 nanofluids of 10:90 and 30:70 in Re range of 300 to 1000 were compared to the base fluid. The heat transfer increament of 9.1% and 9.85%. was observed. However, the pressure drop was also increased in the range of 22 Pa to 26 Pa for 0.5 % of Al2O3:SiO2 of 10:90 and 30:70 consecutively as compared to the base fluid. The advantage ratio was then analyzed to show the feasibility of both ratios of 0.5 % hybrid nanofluid of Al2O3:SiO2 at 10:90 and 30:70. It shows that both have advantage ratio higher than 1, thus feasible for the adoption in a PEMFC.

Molecular M-N4 macrocycles in a nitrogen-carbon matrix as a highly durable oxygen reduction reaction (ORR) electrocatalysts in acid media

Proton electrolyte membrane fuel cell (PEMFC) is one of the most popular clean energy systems, which has attracted attention in a few recent years. However, due to the sluggish oxygen reduction reaction (ORR) in acid media, platinum-based catalysts are highly required in the-state-of-the-art PEMFC. Also, the low durability and scarcity of novel metals significantly limit its wide application. This study applied a novel plasma engineering route to fabricate molecular transition metal macrocycles (M-N4 where M = Fe, Co, Mn) in situ into nitrogen-carbon support. CoN4 showed the highest ORR onset (Eonset) and halfwave potential (E1/2) of 0.78 and 0.67 V vs. RHE, respectively, which was only slightly inferior by 100 mV in ORR onset compared to the benchmark 20 wt.% Pt/C. On the other hand, CoN4 presented extremely high durability (E1/2 = −15 mV after 3000 cycles) and outperformed 20 wt.% Pt/C (E1/2 = −140 mV after 3000 cycles). This study presented a novel plasma engineering to fabricate molecular transitional metal-N4 doped carbon as a highly durable and economic ORR electrocatalyst to replace current benchmark Pt-based metal for PEMFC.

Equilibrium optimizer for parameter extraction of a fuel cell dynamic model

The representative model of fuel cells (FCs) has a vital role in investigating the steady-state and dynamic analysis of these cells. The FC model has a significant impact on simulation studies of such systems and this is appeared in several applications like nano grids, microgrids and smart grids. This manuscript attempts a novel and simplified precise model of the proton electrolyte membrane FCs (PEMFCs). The proposed model deeply reduces the number of unknown parameters of such models to achieve a simplified one. In this regard, it reveals only four design variables within the model. Another salient feature of this study is the novel application of a meta-heuristic algorithm called equilibrium optimizer (EO) to obtain these unknown four parameters. The integral squared error criteria is used to formulate the fitness function. The effectiveness of EO-PEMFC model is tested by comparing the simulation with experimental results under various operating situations. The validity of proposed model is also verified by benchmarking its results with that obtained using other optimization-based models. The high efficacy of this model is checked under both steady-state and dynamic operating conditions. With the application of the proposed model, a very precise PEMFC model can be implemented.

The use of Additive Manufactured Inconel 625 as Bipolar Plate for the High Temperature Proton Electrolyte Membrane Fuel Cell

Inconel 625 is a promising candidate as base material for bipolar plates in the High Temperature Proton Electrolyte Membrane Fuel Cell (HT-PEMFC), due to its mechanical strength and anti-corrosive properties. Due to its often complicated flow channel networks both internally and externally, production time and costs are significant factors to the total fuel cell manufacturing costs. Additive manufacturing (AM) might be a promising production method, though it is important that the material have its desirable properties intact. This includes corrosion resistance towards concentrated phosphoric acid (H3PO4) at elevated temperatures (120 °C- 200 °C) and exposed to different voltage values. In this work, flat Inconel 625 samples have been manufactured using AM followed by post-machining of its surface to an arithmetic roughness average (Ra) of ~0.3 |j.m. These samples were electro-chemically tested for its anti-corrosive properties while exposed to concentrated H3PO4 at 150 °C and a potential of 0.65 V vs the reversible hydrogen electrode (RHE). The sample surfaces were analysed using scanning electron microscopy (SEM) before and after the corrosion experiment. The interfacial contact resistance (ICR), a measure for the resistance towards electron conductivity through the corrosion-exposed surface with an adjacent conducting material, was also measured before and after the corrosion tests. For comparison, hot rolled Inconel 625 sample commercially purchased and post-machined to the same Ra-value was tested for its corrosion properties and compared to the AM-produced Inconel 625 sample. The AM-sample had a higher corrosion rate compared to the commercial with a corrosion penetration rate (CPR) almost twice as high. The measured ICR of the commercial sample was over 3.5 times higher than for the AM-sample after the corrosion test, indicating a less successful formation and thickness development of a protective phase on the AM-sample surface. Despite of equivalent surface roughness, the corrosion properties between the two production methods are significantly different, which are thought to be linked to different microstructures formed during their manufacturing.

A Long‐term Energy Management Strategy for Fuel Cell Electric Vehicles Using Reinforcement Learning

AbstractThe two power sources of a fuel cell electric vehicle (FCEV) are proton electrolyte membrane fuel cell (PEMFC) and Li‐ion battery (LIB). The health status of PEMFC and LIB decreases with the use of FCEV, so the energy management strategy (EMS) needs to give an optimal power distribution based on the health status of power sources throughout the lifetime. However, rule‐based control strategies cannot achieve this. To prolong the service lifetime of two power sources by optimizing power distribution, this article proposes a long‐term energy management strategy (LTEMS) for FCEV, which contains a reinforcement learning module and an improved thermostat controller. By designing a reward function, the reinforcement learning module outputted various LIB state of charge (SOC) boundary which changes with power source attenuation. Based on SOC boundary, the improved thermostat controller will control the fuel cell current under specific driving conditions. Simulation was carried out based on different LIB state of health (SOH) and external temperature, and the simulation results were compared with the data collected from FCEV under rule‐based (RB) strategies. It can be found that the proposed LTEMS can effectively reduce fuel cell and LIB attenuation, and meet the FCEV power demand.

Simulation analysis of hydrogen recirculation rates of fuel cells and the efficiency of combined heat and power

The objective of this study was to simulate a proton-electrolyte membrane fuel cell (PEMFC) system, namely a PEMFC stack, an anode gas supply subsystem, an anode gas-recovery subsystem, a cathode gas supply subsystem, and a tail gas exhaustion subsystem. In addition, this paper presents an analysis of the efficiency of combined heat and power (CHP) systems. MATLAB and Simulink were employed for dynamic simulation and statistical analysis. The rates of active and the passive anode hydrogen recirculation were considered to elucidate the mechanism of hydrogen circulation. When recovery involved diverse recovery mechanisms, the recirculation rate was affected by the pressure at the hydrogen outlet of the PEMFC system. The greater the pressure was at that outlet, the higher the recovery rate was. In the hydrogen recovery system, when the temperature of the hydrogen supply end remained the same, increasing the temperature of the gas supply end increased the efficiency of the fuel cells; fixing the flow of the hydrogen supply end and increasing the temperature of the hydrogen supply end increased the efficiency of the PEMFC system. A calculation of the efficiency of the recovery system indicated that the thermal efficiency of the fuel cells exceeded 35%, the power generation efficiency exceeded 45%, and the efficiency of the CHP system exceeded 80%.

Numerical Study on the Stress Concentration Phenomenon in the Membranes of PEMFCs in an Assembled State

AbstractMechanical damage to the membrane of the electrode assembly (MEA) in a proton electrolyte membrane fuel cell (PEMFC) is one of the main factors influencing its durability. In this study, a ...

Effect of GDM Pairing on PEMFC Performance in Flow-Through and Dead-Ended Anode Mode.

Asymmetric gas diffusion media (GDM) pairing, which feature distinct GDM at the anode and cathode of the proton electrolyte membrane fuel cell (PEMFC), enhance water management compared to symmetric pairing of GDM (anode and cathode GDM are identical). An asymmetric pairing of Freudenberg GDM (H24C3 at anode and H23C2 at cathode) reduces ohmic resistances by up to 40% and oxygen transport resistances by 14% en route to 25% higher current density in dry gas flows. The asymmetric GDM pairing effectively hydrates the membrane electrode assembly (MEA) while minimizing liquid water saturation in the cathode compared to a commonly used symmetric GDM pairing of SGL 29BC at the anode and cathode. Superior water management observed with asymmetric GDM in flow-through mode is also realized in dead-ended anode (DEA) mode. Compared to the symmetric GDM pairing, the asymmetric GDM pairing with Freudenberg GDM increases cell voltage at all current densities, extends and stabilizes steady-state voltage behavior, slows voltage decay, and vastly reduces the frequency of anode purge events. These results support that the asymmetric Freudenberg GDM combination renders the PEMFC less prone to anode water saturation and performance loss from the anticipated increase in water back-diffusion during DEA mode operation.

An experimental investigation of three-dimensional mechanical characteristics of gas diffusion layers in proton electrolyte membrane fuel cells

In this study, three-dimensional (3D) orthotropic mechanical properties of a commercial gas diffusion layer (GDL) are experimentally investigated. Although GDL is an important 3D structural membrane in proton electrolyte membrane fuel cells (PEMFCs), most papers have merely considered its in-plane linear isotropic characteristics due to the lack of 3D anisotropic mechanical performance investigation. In real operating PEMFCs, GDL is nonlinear orthotropic composite and its mechanical characteristics affect the overall performance of PEMFCs, seriously and directly. In this research, as considering GDL’s valid configuration in PEMFCs, mechanical tests such as compression test, tension test, and shear test are conducted to study its 3D mechanical behavior. Test results present that the GDL behaves in an orthotropic and nonlinear manner. In addition, microstructures of the GDL are observed through scanning electron microscope (SEM) images, to explain its different kinds of mechanical failure performance.

Comparative performance evaluation of self-humidifying PEMFCs with short-side-chain and long-side-chain membranes under various operating conditions

The performance of a proton electrolyte membrane fuel cell (PEMFC) with a perfluorosulfonic-acid-based membrane is strongly dependent on the water content in the membrane. In this study, comparative performance evaluation of self-humidifying PEMFCs with short-side-chain (SSC) and long-side-chain (LSC) membranes is conducted under various operating temperatures, air stoichiometries, back pressures, and voltages. The optimal operating conditions at each voltage are determined by using response surface methodology. The self-humidifying PEMFC with the SSC membrane exhibits higher power density than that with the LSC membrane owing to higher water retention. The dominant operating parameter for the system performance changes from the back pressure to air stoichiometry with a decrease in the voltage. Moreover, based on the dynamic response tests, the self-humidifying PEMFC with the SSC membrane exhibits better reliability and settling time than that with the LSC membrane.

Performance Improvement of Proton Exchange Membrane Fuel Cell

Fuel cell is a device which is used to produce chemical energy into electrical energy. Proton Electrolyte Membrane fuel cell (PEMFC) was not polluting the environment and it has high efficiency. PEM fuel cell, in addition to electricity, water and small amount of heat are generated as by-products. This generated water on cathode side blocks the flow paths and reducing electrochemical reactions. So the low electrochemical reactions will affect the performance of fuel cell. To increase the performance of fuel cell, we can change the flow parameters and flow field design. A 3D model of new flow field channel has been designed with 25 cm2 active area with SOLID WORKS 2008. The solid model has been analyzed with ANSYS 14.5 software. Numerical values of PEMFC were obtained with ANSYS FLUENT 14.5. Comparison has been made for power density of new flow field design with power density of serpentine flow field design.

Reliability prediction of large fuel cell stack based on structure stress analysis

The aim of this paper is to improve the reliability of Proton Electrolyte Membrane Fuel Cell (PEMFC) stack by designing the clamping force and the thickness difference between the membrane electrode assembly (MEA) and the gasket. The stack reliability is directly determined by the component reliability, which is affected by the material property and contact stress. The component contact stress is a random variable because it is usually affected by many uncertain factors in the production and clamping process. We have investigated the influences of parameter variation coefficient on the probability distribution of contact stress using the equivalent stiffness model and the first-order second moment method. The optimal contact stress to make the component stay in the highest level reliability is obtained by the stress-strength interference model. To obtain the optimal contact stress between the contact components, the optimal thickness of the component and the stack clamping force are optimally designed. Finally, a detailed description is given how to design the MEA and gasket dimensions to obtain the highest stack reliability. This work can provide a valuable guidance in the design of stack structure for a high reliability of fuel cell stack.

Energy management of PEM fuel cell/ supercapacitor hybrid power sources for an electric vehicle

This paper presents the utilization of a supercapacitor (SC) as an auxiliary power source in an electric vehicle (EV), composed of a proton electrolyte membrane fuel cell (PEMFC) as the main energy source. The main weak point of PEMFC is slow dynamics because one must limit the fuel cell current slope in order to prevent fuel starvation problems, to improve its performance and lifetime. The very fast power response and high specific power of a supercapacitor can complement the slower power output of the main source to produce the compatibility and performance characteristics needed in a propulsion system. DC-DC converters connected to the hybrid source ensure a constant voltage value in inverters inputs. After an architecture presentation of the hybrid energy source, two parallel-type configurations are explored in more detail. For each of them, the energy flow control and management, validated simulation shows the performance obtained in this configuration. The hybrid source management is based primarily on the intervention of the supercapacitor in fugitives' schemes such as slopes, different speeds and rapid acceleration. Secondly, the PEMFC intervenes to guarantee the power in permanent regime. Finally, simulation results considering energy management are presented and illustrated the hybrid energy source benefits.

Facile Fabrication of Bimetallic PtCo Nanoparticles Supported on Three-Dimensional Reduced Graphene Oxide by Ultrasonic-Assisted Method for Oxygen Reduction Reaction

High platinum requirements in electrocatalyst bring about huge expenditure, which hinders the commercialization and wide adoption of proton electrolyte membrane fuel cells (PEMFCs). Therefore, developing new fuel cell catalysts with excellent oxygen reduction reaction (ORR) performance may be a potential way to solve this drawback. In this paper, a facile ultrasonic-assisted method is introduced to synthesize bimetallic PtCo nanoparticles supported on three-dimensional reduced graphene oxide (Pt-Co/3DrGO). Results indicate that PtCo nanoparticles with alloy structure, small size (12.4 nm), and uniform distribution are well-dispersed onto rGO sheets. With 3D porous structure, the fabricated Pt-Co/3DrGO catalyst exhibits better ORR activity and long-term stability than that of commercial Pt/C (20 wt%). The increased electrocatalytic activity is attributed to the formation of 3D porous structure together with the effective surface structure and the highly uniform distribution of the PtCo alloy nanoparticles on rGO sheets.

Electrochemical Deposition of PGM Based Fuel Cell Electro Catalysts

The talk will focus on the applications of electrochemistry and nanotechnology for the synthesis and characterisation of electro-catalysts used in fuel cells. Electrochemical methods such as, Electrochemical Atomic Layer Epitaxy (EC-ALE) and Electrochemical Atomic Layer Deposition (EC-ALD) are being explored for synthesis as other potential techniques used in the improvement of PGM based electro-catalysts for proton electrolyte membrane fuel cells (PEMFCs). Synthesis and characterisation of these electro-catalysts (nanostructured/ nanomaterials), including their proposed application in fuel cells, will be discussed as part of the talk. The connection of the electro-catalysis work to alkaline direct alcohol fuel cells (DAFCs) with focus on micro fuel cells and anionic membrane development will also be highlighted. ACKNOWLEDGEMENT The author wish to acknowledge the DST, NRF and CSIR for funding.

Self-Healing Composite Membrane for Proton Electrolyte Membrane Fuel Cell Applications

We have developed a self-healing membrane based on microcapsules prefilled with Nafion solution. The microcapsules are designed to rupture when they encounter defects formed in the membrane such as cracks and pinholes, and then release the prefilled Nafion solution to heal the defects in-situ. A procedure was developed to prepare microcapsules with a urea-formaldehyde shell prefilled with a Nafion/tributyl phosphate self-healing solution. The prepared microcapsules were characterized by SEM with focused ion beam (FIB) and optical microscopy. Proton conductivity, mechanical properties, swelling and water uptake of the composite membranes based on microcapsules were measured and compared with that of pure recast Nafion membranes. Fuel cell performance with 6 and 10 wt% microcapsules/Nafion membranes was compared with that of a pure recast Nafion membrane. Durability testing comprising 220 hours of OCV-hold with relative humidity cycling confirmed that the self-healing functionality could greatly extend the life span of the fuel cell membrane.