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1058 KiB

Open AccessArticle

Importance of Fuel Cell Tests for Stability Assessment—Suitability of Titanium Diboride as an Alternative Support Material

by Christina Roth, Peter Bleith, Christoph A. Schwöbel, Sebastian Kaserer and Jens Eichler

Energies 2014, 7(6), 3642-3652; https://doi.org/10.3390/en7063642 - 11 Jun 2014

Cited by 11 | Viewed by 9663

Abstract

Carbon corrosion is a severe issue limiting the long-term stability of carbon-supported catalysts, in particular in the highly dynamic conditions of automotive applications. (Doped) oxides have been discussed as suitable alternatives to replace carbon, but often suffer from poor electron conductivity. That is [...] Read more.

Carbon corrosion is a severe issue limiting the long-term stability of carbon-supported catalysts, in particular in the highly dynamic conditions of automotive applications. (Doped) oxides have been discussed as suitable alternatives to replace carbon, but often suffer from poor electron conductivity. That is why non-oxide ceramics, such as tungsten carbide and titanium nitride, have been discussed recently. Titanium diboride has also been proposed, due to its promising activity and stability in an aqueous electrochemical cell. In this work, Pt nanoparticles were deposited onto μm-sized TiB₂ particles with improved grain size, manufactured into porous gas diffusion electrodes and tested in a realistic polymer electrolyte membrane (PEM) fuel cell environment. In contrast to the model studies in an aqueous electrochemical cell, in the presence of oxygen and high potentials at the cathode side of a real fuel cell, TiB₂ becomes rapidly oxidized as indicated by intensely colored regions in the membrane-electrode assembly (MEA). Moreover, already the electrode manufacturing process led to the formation of titanium oxides, as shown by X-ray diffraction measurements. This demonstrates that Cyclic Voltammetry (CV) measurements in an aqueous electrochemical cell are not sufficient to prove stability of novel materials for fuel cell applications. Full article

(This article belongs to the Special Issue Polymer Electrolyte Membrane Fuel Cells)

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903 KiB

Open AccessArticle

An Energy Management System of a Fuel Cell/Battery Hybrid Boat

by Jingang Han, Jean-Frederic Charpentier and Tianhao Tang

Energies 2014, 7(5), 2799-2820; https://doi.org/10.3390/en7052799 - 28 Apr 2014

Cited by 182 | Viewed by 16556

Abstract

All-electric ships are now a standard offering for energy/propulsion systems in boats. In this context, integrating fuel cells (FCs) as power sources in hybrid energy systems can be an interesting solution because of their high efficiency and low emission. The energy management strategy [...] Read more.

All-electric ships are now a standard offering for energy/propulsion systems in boats. In this context, integrating fuel cells (FCs) as power sources in hybrid energy systems can be an interesting solution because of their high efficiency and low emission. The energy management strategy for different power sources has a great influence on the fuel consumption, dynamic performance and service life of these power sources. This paper presents a hybrid FC/battery power system for a low power boat. The hybrid system consists of the association of a proton exchange membrane fuel cell (PEMFC) and battery bank. The mathematical models for the components of the hybrid system are presented. These models are implemented in Matlab/Simulink environment. Simulations allow analyzing the dynamic performance and power allocation according to a typical driving cycle. In this system, an efficient energy management system (EMS) based on operation states is proposed. This EMS strategy determines the operating point of each component of the system in order to maximize the system efficiency. Simulation results validate the adequacy of the hybrid power system and the proposed EMS for real ship driving cycles. Full article

(This article belongs to the Special Issue Polymer Electrolyte Membrane Fuel Cells)

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2236 KiB

Open AccessArticle

Compact Design of 10 kW Proton Exchange Membrane Fuel Cell Stack Systems with Microcontroller Units

by Hsiaokang Ma, Weiyang Cheng, Fuming Fang, Chinbing Hsu and Chengsheng Lin

Energies 2014, 7(4), 2498-2514; https://doi.org/10.3390/en7042498 - 22 Apr 2014

Cited by 7 | Viewed by 9472

Abstract

In this study, fuel, oxidant supply and cooling systems with microcontroller units (MCU) are developed in a compact design to fit two 5 kW proton exchange membrane fuel cell (PEMFC) stacks. At the initial stage, the testing facility of the system has a [...] Read more.

In this study, fuel, oxidant supply and cooling systems with microcontroller units (MCU) are developed in a compact design to fit two 5 kW proton exchange membrane fuel cell (PEMFC) stacks. At the initial stage, the testing facility of the system has a large volume (2.0 m × 2.0 m × 1.5 m) with a longer pipeline and excessive control sensors for safe testing. After recognizing the performance and stability of stack, the system is redesigned to fit in a limited space (0.4 m × 0.5 m × 0.8 m). Furthermore, the stack performance is studied under different hydrogen recycling modes. Then, two similar 5 kW stacks are directly coupled with diodes to obtain a higher power output and safe operation. The result shows that the efficiency of the 5 kW stack is 43.46% with a purge period of 2 min with hydrogen recycling and that the hydrogen utilization rate µ_f is 66.31%. In addition, the maximum power output of the twin-coupled module (a power module with two stacks in electrical cascade/parallel arrangement) is 9.52 kW. Full article

(This article belongs to the Special Issue Polymer Electrolyte Membrane Fuel Cells)

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716 KiB

Open AccessArticle

Preparation of Polybenzimidazole-Based Membranes and Their Potential Applications in the Fuel Cell System

by Kyungho Hwang, Jun-Hyun Kim, Sung-Yul Kim and Hongsik Byun

Energies 2014, 7(3), 1721-1732; https://doi.org/10.3390/en7031721 - 24 Mar 2014

Cited by 47 | Viewed by 11368

Abstract

Various polybenzimidazole (PBI)-based ion-exchange films were prepared and thoroughly characterized by Fourier transform infrared (FT-IR) spectroscopy, proton conductivity, and water uptake for possible use as fuel cell membranes. Upon the increase in the flexibility of the PBI-based polymer films (e.g., poly(oxyphenylene benzimidazole) (OPBI) [...] Read more.

Various polybenzimidazole (PBI)-based ion-exchange films were prepared and thoroughly characterized by Fourier transform infrared (FT-IR) spectroscopy, proton conductivity, and water uptake for possible use as fuel cell membranes. Upon the increase in the flexibility of the PBI-based polymer films (e.g., poly(oxyphenylene benzimidazole) (OPBI) and sulfonated OPBI (s-OPBI)), the membranes exhibited slightly improved proton conductivity, but significantly increased dimensional changes. To reduce the dimensional changes (i.e., increase the stability), the cross-linking of the polymer films (e.g., cross-linked OPBI (c-OPBI) and sulfonated c-OPBI (sc-OPBI)) was accomplished using phosphoric acid. Interestingly, the sc-OPBI membrane possessed a greatly increased proton conductivity (0.082 S/cm), which is comparable to that of the commercially available Nafion membrane (0.09 S/cm), while still maintaining slightly better properties regarding the dimensional change and water uptake than those of the Nafion membrane. Full article

(This article belongs to the Special Issue Polymer Electrolyte Membrane Fuel Cells)

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1022 KiB

Open AccessArticle

Modelling of PEM Fuel Cell Performance: Steady-State and Dynamic Experimental Validation

by Idoia San Martín, Alfredo Ursúa and Pablo Sanchis

Energies 2014, 7(2), 670-700; https://doi.org/10.3390/en7020670 - 10 Feb 2014

Cited by 88 | Viewed by 12472

Abstract

This paper reports on the modelling of a commercial 1.2 kW proton exchange membrane fuel cell (PEMFC), based on interrelated electrical and thermal models. The electrical model proposed is based on the integration of the thermodynamic and electrochemical phenomena taking place in the [...] Read more.

This paper reports on the modelling of a commercial 1.2 kW proton exchange membrane fuel cell (PEMFC), based on interrelated electrical and thermal models. The electrical model proposed is based on the integration of the thermodynamic and electrochemical phenomena taking place in the FC whilst the thermal model is established from the FC thermal energy balance. The combination of both models makes it possible to predict the FC voltage, based on the current demanded and the ambient temperature. Furthermore, an experimental characterization is conducted and the parameters for the models associated with the FC electrical and thermal performance are obtained. The models are implemented in Matlab Simulink and validated in a number of operating environments, for steady-state and dynamic modes alike. In turn, the FC models are validated in an actual microgrid operating environment, through the series connection of 4 PEMFC. The simulations of the models precisely and accurately reproduce the FC electrical and thermal performance. Full article

(This article belongs to the Special Issue Polymer Electrolyte Membrane Fuel Cells)

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334 KiB

Open AccessArticle

Linearization and Input-Output Decoupling for Nonlinear Control of Proton Exchange Membrane Fuel Cells

by Long-Yi Chang and Hung-Cheng Chen

Energies 2014, 7(2), 591-606; https://doi.org/10.3390/en7020591 - 27 Jan 2014

Cited by 12 | Viewed by 7029

Abstract

This paper presents a nonlinear control strategy utilizing the linearization and input-output decoupling approach for a nonlinear dynamic model of proton exchange membrane fuel cells (PEMFCs). The multiple-input single-output (MISO) nonlinear model of the PEMFC is derived first. The dynamic model is then [...] Read more.

This paper presents a nonlinear control strategy utilizing the linearization and input-output decoupling approach for a nonlinear dynamic model of proton exchange membrane fuel cells (PEMFCs). The multiple-input single-output (MISO) nonlinear model of the PEMFC is derived first. The dynamic model is then transformed into a multiple-input multiple-output (MIMO) square system by adding additional states and outputs so that the linearization and input-output decoupling approach can be directly applied. A PI tracking control is also introduced to the state feedback control law in order to reduce the steady-state errors due to parameter uncertainty. This paper also proposes an adaptive genetic algorithm (AGA) for the multi-objective optimization design of the tracking controller. The comprehensive results of simulation demonstrate that the PEMFC with nonlinear control has better transient and steady-state performance compared to conventional linear techniques. Full article

(This article belongs to the Special Issue Polymer Electrolyte Membrane Fuel Cells)

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362 KiB

Open AccessArticle

Polarization Curve of a Non-Uniformly Aged PEM Fuel Cell

by Andrei Kulikovsky

Energies 2014, 7(1), 351-364; https://doi.org/10.3390/en7010351 - 16 Jan 2014

Cited by 9 | Viewed by 7283

Abstract

We develop a semi-analytical model for polarization curve of a polymer electrolyte membrane (PEM) fuel cell with distributed (aged) along the oxygen channel MEA transport and kinetic parameters of the membrane–electrode assembly (MEA). We show that the curve corresponding to varying along the [...] Read more.

We develop a semi-analytical model for polarization curve of a polymer electrolyte membrane (PEM) fuel cell with distributed (aged) along the oxygen channel MEA transport and kinetic parameters of the membrane–electrode assembly (MEA). We show that the curve corresponding to varying along the channel parameter, in general, does not reduce to the curve for a certain constant value of this parameter. A possibility to determine the shape of the deteriorated MEA parameter along the oxygen channel by fitting the model equation to the cell polarization data is demonstrated. Full article

(This article belongs to the Special Issue Polymer Electrolyte Membrane Fuel Cells)

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1487 KiB

Open AccessArticle

Functionalization of Aligned Carbon Nanotubes to Enhance the Performance of Fuel Cell

by Jingbo Liu, Yuan Yuan and Sajid Bashir

Energies 2013, 6(12), 6476-6486; https://doi.org/10.3390/en6126476 - 16 Dec 2013

Cited by 17 | Viewed by 5839

Abstract

The focus of this research lies on fundamental research to provide guidelines for the design of new nanocatalyst toward improvement of the performance of proton exchange membrane fuel cells (PEMFCs). To achieve this overarching goal, several specific steps were taken with aims to: [...] Read more.

The focus of this research lies on fundamental research to provide guidelines for the design of new nanocatalyst toward improvement of the performance of proton exchange membrane fuel cells (PEMFCs). To achieve this overarching goal, several specific steps were taken with aims to: (1) provide guidelines for the design of new catalysts; (2) promote nanocatalyst applications towards alternative energy applications; and (3) integrate advanced instrumentation into nanocharacterization and fuel cell (FC) electrochemical behavior. In tandem with these goals, the cathode catalysts were extensively refined to improve the performance of PEMFCs and minimize noble metal usage. In this study, the major accomplishment was producing aligned carbon nanotubes (ACNTs), which were then modified by platinum (Pt) nanoparticles via a post-functionalization colloidal chemistry approach. The Pt-ACNTs demonstrated improved cathodic catalycity, by building better device endurance and decreased Pt loading. It was also determined that surface mechanical properties, such as elastic modulus and hardness were increased. Collectively, these enhancements provided an improved FC device. The electrochemical analyses indicated that the power density of the PEMFCs was increased to 900 mW/cm² and current density to 3000 mA/cm², respectively. The Pt loading was controlled at lower than 0.2 mg/cm² to decrease the manufacturing expenses. Full article

(This article belongs to the Special Issue Polymer Electrolyte Membrane Fuel Cells)

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278 KiB

Open AccessArticle

Experimental Study on a Passive Fuel Cell/Battery Hybrid Power System

by Yong-Song Chen, Sheng-Miao Lin and Boe-Shong Hong

Energies 2013, 6(12), 6413-6422; https://doi.org/10.3390/en6126413 - 10 Dec 2013

Cited by 29 | Viewed by 6964

Abstract

A laboratory-scale passive hybrid power system for transportation applications is constructed and tested in this study. The hybrid power system consists of a fuel cell stack connected with a diode, a lithium-ion battery pack connected with a DC/DC power converter and another diode. [...] Read more.

A laboratory-scale passive hybrid power system for transportation applications is constructed and tested in this study. The hybrid power system consists of a fuel cell stack connected with a diode, a lithium-ion battery pack connected with a DC/DC power converter and another diode. The power converter is employed to regulate the output voltage of the battery pack. The dynamic responses of current and voltage of the stack to the start-up and acceleration of the load are experimentally investigated at two different selected output voltages of the DC/DC converter in the battery line. The power sharing of each power source and efficiency are also analyzed and discussed. Experimental results show that the battery can compensate for the shortage of supplied power for the load demand during the start-up and acceleration. The lowest operating voltage of the fuel cell stack is limited by the regulated output voltage of the DC/DC converter. The major power loss in the hybrid power system is attributed to the diodes. The power train efficiency can be improved by lowering the ratio of forward voltage drop of the diode to the operating voltage of the fuel cell stack. Full article

(This article belongs to the Special Issue Polymer Electrolyte Membrane Fuel Cells)

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4708 KiB

Open AccessArticle

An Innovative Hybrid 3D Analytic-Numerical Approach for System Level Modelling of PEM Fuel Cells

by Gregor Tavčar and Tomaž Katrašnik

Energies 2013, 6(10), 5426-5485; https://doi.org/10.3390/en6105426 - 21 Oct 2013

Cited by 11 | Viewed by 5926

Abstract

The PEM fuel cell model presented in this paper is based on modelling species transport and coupling electrochemical reactions to species transport in an innovative way. Species transport is modelled by obtaining a 2D analytic solution for species concentration distribution in the plane [...] Read more.

The PEM fuel cell model presented in this paper is based on modelling species transport and coupling electrochemical reactions to species transport in an innovative way. Species transport is modelled by obtaining a 2D analytic solution for species concentration distribution in the plane perpendicular to the gas-flow and coupling consecutive 2D solutions by means of a 1D numerical gas-flow model. The 2D solution is devised on a jigsaw puzzle of multiple coupled domains which enables the modelling of parallel straight channel fuel cells with realistic geometries. Electrochemical and other nonlinear phenomena are coupled to the species transport by a routine that uses derivative approximation with prediction-iteration. A hybrid 3D analytic-numerical fuel cell model of a laboratory test fuel cell is presented and evaluated against a professional 3D computational fluid dynamic (CFD) simulation tool. This comparative evaluation shows very good agreement between results of the presented model and those of the CFD simulation. Furthermore, high accuracy results are achieved at computational times short enough to be suitable for system level simulations. This computational efficiency is owed to the semi-analytic nature of its species transport modelling and to the efficient computational coupling of electrochemical kinetics and species transport. Full article

(This article belongs to the Special Issue Polymer Electrolyte Membrane Fuel Cells)

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13209 KiB

Open AccessArticle

Modeling the Liquid Water Transport in the Gas Diffusion Layer for Polymer Electrolyte Membrane Fuel Cells Using a Water Path Network

by Robert Alink and Dietmar Gerteisen

Energies 2013, 6(9), 4508-4530; https://doi.org/10.3390/en6094508 - 2 Sep 2013

Cited by 25 | Viewed by 7967

Abstract

In order to model the liquid water transport in the porous materials used in polymer electrolyte membrane (PEM) fuel cells, the pore network models are often applied. The presented model is a novel approach to further develop these models towards a percolation model [...] Read more.

In order to model the liquid water transport in the porous materials used in polymer electrolyte membrane (PEM) fuel cells, the pore network models are often applied. The presented model is a novel approach to further develop these models towards a percolation model that is based on the fiber structure rather than the pore structure. The developed algorithm determines the stable liquid water paths in the gas diffusion layer (GDL) structure and the transitions from the paths to the subsequent paths. The obtained water path network represents the basis for the calculation of the percolation process with low calculation efforts. A good agreement with experimental capillary pressure-saturation curves and synchrotron liquid water visualization data from other literature sources is found. The oxygen diffusivity for the GDL with liquid water saturation at breakthrough reveals that the porosity is not a crucial factor for the limiting current density. An algorithm for condensation is included into the model, which shows that condensing water is redirecting the water path in the GDL, leading to an improved oxygen diffusion by a decreased breakthrough pressure and changed saturation distribution at breakthrough. Full article

(This article belongs to the Special Issue Polymer Electrolyte Membrane Fuel Cells)

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Review

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1830 KiB

Open AccessReview

A Review on Cold Start of Proton Exchange Membrane Fuel Cells

by Zhongmin Wan, Huawei Chang, Shuiming Shu, Yongxiang Wang and Haolin Tang

Energies 2014, 7(5), 3179-3203; https://doi.org/10.3390/en7053179 - 13 May 2014

Cited by 110 | Viewed by 12528

Abstract

Successful and rapid startup of proton exchange membrane fuel cells (PEMFCs) at subfreezing temperatures (also called cold start) is of great importance for their commercialization in automotive and portable devices. In order to maintain good proton conductivity, the water content in the membrane [...] Read more.

Successful and rapid startup of proton exchange membrane fuel cells (PEMFCs) at subfreezing temperatures (also called cold start) is of great importance for their commercialization in automotive and portable devices. In order to maintain good proton conductivity, the water content in the membrane must be kept at a certain level to ensure that the membrane remains fully hydrated. However, the water in the pores of the catalyst layer (CL), gas diffusion layer (GDL) and the membrane may freeze once the cell temperature decreases below the freezing point (T_f). Thus, methods which could enable the fuel cell startup without or with slight performance degradation at subfreezing temperature need to be studied. This paper presents an extensive review on cold start of PEMFCs, including the state and phase changes of water in PEMFCs, impacts of water freezing on PEMFCs, numerical and experimental studies on PEMFCs, and cold start strategies. The impacts on each component of the fuel cell are discussed in detail. Related numerical and experimental work is also discussed. It should be mentioned that the cold start strategies, especially the enumerated patents, are of great reference value on the practical cold start process. Full article

(This article belongs to the Special Issue Polymer Electrolyte Membrane Fuel Cells)

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