Gas diffusion layer (GDL) and its interfaces with the flow channel and microporous layer or catalyst layer in polymer electrolyte fuel cells (PEFCs) play a significant role in water management and heat removal from the cells. Both surface morphology and surface wettability of GDL influence and control the water transport in PEFCs. Thus, the surface morphology and selectivity of its surface wettability are critical for PEFCs to provide optimum outputs. In this study, we have reported the fabrications of GDLs with a selective wetting pattern. Sigracet® GDLs were used as a substrate and two different monomers, polydimethylsiloxane (PDMS) added with fumed silica (Si) and fluorinated ethylene propylene (FEP) were used to print a selective pattern on the GDL surfaces. The evaluations of printed GDL surfaces, by means of static contact angle, sliding angles and scanning electron microscopy image, show that superhydrophobicity was achieved with both FEP and PDMS-Si coatings. Fourier Transform Infrared (FTIR) spectroscopy analysis confirmed the successful introduction of the functional groups in both the coatings. Finally, pore size distribution, sliding angle measurements and adhesion forces were used to investigate the interactions between the water droplets and GDL surfaces. The results of this study demonstrate that the present approach provides a novel but simple way to tune GDL surfaces with selective wetting properties and obtain superhydrophobic interfaces. The electrochemical results showed that an improvement can be achieved for the performance of PEFCs with patterned GDL/flow-channel interfaces.

The energy, exergy and economic aspects are analyzed of a cycle consisting of a polymer fuel cell, a burner, a reformer and a heat exchanger. Water is used for cooling the fuel cell, and the heated water is used for domestic consumption. The exergy and energy efficiencies of the cycle are calculated and the effects of various cycle parameters on the exergy and energy efficiencies are investigated. To maximize the exergy efficiency while minimizing the cost of electricity generation by the fuel cell, the PSO algorithm is utilized. The results show that increasing the cooling water flow rate has the greatest effect on increasing the energy efficiency of the cycle, while increasing the burner temperature has the greatest effect on increasing the exergy efficiency of the cycle. Moreover, it is shown via multiobjective optimization of the proposed cycle that the exergy efficiency of the cycle increases by 38% and the cost of electricity generation decreases by 18% by applying optimized parameters.

In a previous numerical study on heat and mass transfer in air-cooled proton exchange membrane fuel cells, it was found that the performance is limited by heat transfer to the cathode side air stream that serves as a coolant, and it was proposed to place a turbulence grid before the cathode inlet in order to induce a mixing effect to the air and thereby improve the heat transfer and ultimately increase the limiting current and maximum power density. The current work summarizes experiments with different turbulence grids which varied in terms of their pore size, grid thickness, rib width, angle of the pores, and the distance between the grid and the cathode inlet. For all grids tested in this study, the limiting current density of a Ballard Mark 1020 ACS stack was increased by 20%. The single most important parameter was the distance between the turbulence grid and the cathode inlet, and it should be within 5 mm. For the best grid tested, the fuel cell stack voltage and thus the efficiency were increased by up to 20%. The power density was increased by more than 30% and further improvements are believed to be possible.

The entire world is facing a great shortfall in the energy supply due to the high consumption rate of fossil fuel-based energy resources. Solid oxide fuel cells (SOFCs) are the best alternative energy devices, which convert hydrogen fuel directly into electricity. Alkali carbonated calcium-doped ceria electrolytes (LNK-CDC) as (Ce 0.8 Ca 0.2 ), (Ce 0.7 Ca 0.3 ), and (Ce 0.6 Ca 0.4 ) were synthesized by the co-precipitation method. With the addition of alkali carbonate, nanocomposites of ceria are well preserved after sintering at 600–700 °C. The structural and morphological properties were examined by X-ray diffraction (XRD) and scanning electron microscopy (SEM), respectively. Crystallite sizes were found in the range of 50–80 nm. The maximum ionic conductivity of LNK-CDC (Ce 0.8 Ca 0.2 ) was achieved to be 0.14 S/cm at 650 °C for anion vacancy migration by the dense microstructure. The minimum activation energy was determined to be 0.23 eV. The Fourier-transform infrared spectroscopy (FTIR) spectra of the prepared materials show the absorbance of IR and their behavior. The maximum power density of symmetric fuel cells LNK-CDC sandwiched with LNCZ oxide electrodes was recorded as 0.52 W cm −2 at 650 °C in the presence of hydrogen (fuel). It is suggested that coating of the equal molar ratio of ternary alkali metals on ceria doped comparatively enhance the performance of new nanocomposite electrolyte for SOFC and other energy applications.

In this paper, an economical and simple procedure was adopted for the fabrication of chemically crosslinked polyvinyl alcohol (PVA)-based KOH-doped alkaline membrane for the use in an alkaline direct ethanol fuel cell (ADEFC). The membrane parameters, namely, water uptake, KOH uptake, and ionic conductivity were systematically evaluated. The ionic conductivity of the synthesized membrane was in the order of 9 × 10 −3 S/cm. The performance of the synthesized alkaline membrane is evaluated in a single ADEFC. Commercial Pt–Ru (30 wt %: 15 wt %)/C and Pt (40 wt %)/high surface area carbon (C HSA ) from Alfa Aesar, Haverhill, MA, were used for anode and cathode, respectively. The performance of the membrane was further evaluated in a single cell using different grades of membranes containing different glutaraldehyde (GA) concentration, anode and cathode electrocatalyst loading, ethanol concentration, and KOH concentration. The maximum open circuit voltage (OCV) of 0.73 V was obtained at a temperature of 35 °C for anode feed containing 2 M ethanol and 1 M KOH for the membrane crosslinked with 2.5 wt % glutaraldehyde doped with 6 M KOH. The maximum power density of 4.15 mW/cm 2 at a current density of 20.69 mA/cm 2 was obtained for the same condition. The optimum electrocatalyst loading was 1 mg/cm 2 of Pt-Ru/C at the anode and 1 mg/cm 2 of Pt/C HSA at the cathode. The performance of KOH-doped chemically crosslinked PVA membrane was comparable with the published literature.

In this work, a model of a proton exchange membrane fuel cell (PEMFC) is presented. A dynamic performance characterization is performed to assess the cell transient response to input variables. The model used in the simulation considers three different phenomena: mass transfer, thermodynamics, and electrochemistry. The main sources of voltage loss are presented: activation, electrical resistance, and concentration. The model is constructed to avoid the use of fitted parameters, reducing the experimentation required for its validation. Hence, the electrochemical model is parameterized by physical variables, including material properties and geometrical characteristics. The model is demonstrated as a test-bed for PEMFC control system design and evaluation. Results demonstrate that the steady-state and dynamic behavior of the system are represented accurately. A case study is included to show the functionality of the model. In the case study, the effect of the purge valves at the fuel cell discharges is analyzed under different scenarios. Regular purges of the cathode and the anode are shown to achieve a good performance in the system avoiding reactant starvation in the cell. A closed-loop dynamic response is included as an example of the model capabilities for the design of fuel cell control strategies. Two variables were selected to be controlled: voltage and pressure difference across the membrane. A multivariate control strategy was tested and its dynamic response was analyzed. It was found that there was a strong interaction between the control loops, making the control of the system a challenge.

The chlor-alkali industry produces significant amounts of hydrogen as by-product which can potentially feed a polymeric electrolyte membrane (PEM) fuel cell (FC) unit, whose electricity and heat production can cover part of the chemical plant consumptions yielding remarkable energy and emission savings. This work presents the modeling, development, and experimental results of a large-scale (2 MW) PEM fuel cell power plant installed at the premises of a chlor-alkali industry. It is first discussed an overview of project’s membrane-electrode assembly and fuel cell development for long life stationary applications, focusing on the design-for-manufacture process and related high-volume manufacturing routes. The work then discusses the modeling of the power plant, including a specific lumped model predicting FC stack behavior as a function of inlet stream conditions and power set point, according to regressed polarization curves. Cells’ performance decay versus lifetime reflects long-term stack test data, aiming to evidence the impact on overall energy balances and efficiency of the progression of lifetime. Balance of plant is modeled to simulate auxiliary consumptions, pressure drops, and components’ operating conditions. The model allows studying different operational strategies that maintain the power production during lifetime, minimizing efficiency losses, as well as to investigate the optimized operating setpoint of the plant at full load and during part-load operation. The last section of the paper discusses the experimental results, through a complete analysis of the plant performance after startup, including energy and mass balances and allowing to validate the model. Cumulated indicators over the first two years of operations regarding energy production, hydrogen consumption, and efficiency are also discussed.

Multilayer nickel–copper coatings consisting of layers of nickel–copper alloy and a mixture of metals with hydroxides were obtained by electrodeposition from polyligand pyrophosphate–ammonia electrolyte by the two-pulse potentiostatic method. A comparison between two different electrodes with the same real surface area is presented. The equality of the surface area of electrodes deposited from the electrolyte containing different copper and nickel ions’ concentration ratio was achieved by deposition of different numbers of layers. It is shown that the increase in the copper content in electrolyte leads to an increase in the copper ions’ content in the coating and the electrode surface develops more intensively. Freshly deposited coatings have approximately the same catalytic activity in the glucose oxidation reaction in the alkaline solution. But a multilayer coating with a higher copper content is more corrosion resistant and more stable in long-term electrolysis.

A computational fluid dynamics model for high-temperature polymer electrolyte fuel cells (PEFC) is developed. This allows for three-dimensional (3D) transport-coupled calculations to be conducted. All major transport phenomena and electrochemical processes are taken into consideration. Verification of the present model is achieved by comparison with current density and oxygen concentration distributions along a one-dimensional (1D) channel. Validation is achieved by comparison with polarization curves from experimental data gathered in-house. Deviations between experimental and numerical results are minor. Internal transport phenomena are also analyzed. Local variations of current density from under channel regions and under rib regions are displayed, as are oxygen mole fractions. The serpentine gas channels contribute positively to gas redistribution in the gas diffusion layers (GDLs) and channels.

In this research, cooling of polymer membrane fuel cells by nanofluids is numerically studied. Single-phase homogeneous technique is used to evaluate thermophysical properties of the water/Al 2 O 3 nanofluid as a function of temperature and nanoparticle concentration. Four cooling plates together with four various fluids (with different nanoparticle concentrations) are considered for cooling fuel cells. The impact of geometry, Reynolds number, and concentration is investigated on some imperative parameters such as surface temperature uniformity and pressure drop. The results reveal that, among different cooling plates, the multipass serpentine flow field has the best performance. It is also proved that the use of nanofluid, in general, enhances the cooling process and significantly improves those parameters directly affecting the fuel cell performance and efficiency. By increasing the nanoparticle concentration by 0.006, the temperature uniformity index will decrease about 13%, the minimum and maximum temperature difference at the cooling plate surface will decrease about 13%, and the pressure drop will increase about 35%. Nanofluids can improve thermal characteristics of cooling systems and consequently enhance the efficiency and durability of fuel cells.

This work investigates the photocatalytic activity of new ferroelectric material with formula (Li 0.95 Cu 0.15 )Ta 0.76 Nb 0.19 O 3 (LT76) in a single chamber microbial fuel cell (MFC) and compares its performance with the similar photocatalyst (Li 0.95 Cu 0.15 )Ta 0.57 Nb 0.38 O 3 (LT57). The photocatalysts LT76 and LT57 were synthesized by ceramic route under the same conditions, with the same starting materials. The ratio Ta/Nb was fixed at 4.0 and 1.5 for LT76 and LT57, respectively. These phases were characterized by different techniques including X-ray diffraction (XRD), transmission electronic microscopy (TEM), particle size distribution (PSD), differential scanning calorimetry (DSC), and ultraviolet (UV)–visible (Vis). The new photocatalyst LT76 presents specific surface area of 0.791 m 2 /g and Curie temperature of 1197 °C. The photocatalytic efficiency of this material is assessed in terms of wastewater treatment and electricity generation by power density and removal rate of chemical oxygen demand (COD) in the presence of a light source. The values of maximum power density and COD removal were 19.77 mW/m 3 and 93%, respectively, for LT76.

Durability and cost are the two major factors limiting the large-scale implementation of fuel cell technology for use in commercial, residential, or transportation applications. The conditioning cost is usually negligible for making proton exchange membrane fuel cells (PEMFCs) at R&D or demo stage with several tens of stacks each year. However, with industry's focus shifting from component development to commercial high-volume manufacturing, the conditioning process requires significant additional capital investments and operating costs, thus becomes one of the bottlenecks for PEMFC manufacturing, particularly at a high production volume (>1000 stack/year). To understand the mechanisms behind PEMFC conditioning, and to potentially reduce conditioning time or even to eliminate the conditioning process, the conditioning behaviors of commercial Nafion™ XL100 and Nafion ® NRE 211 membranes were studied. The potential effects of the membrane additive on fuel cell conditioning were diagnosed using in situ electrochemical impedance spectroscopy (EIS). It was found that the membrane additive led to the significant variation of the charge transfer resistance in EIS during conditioning, which affected the conditioning behavior of the membrane electrode assembly (MEA).

In this paper, we study a solid oxide fuel cell (SOFC) controlled by a multi-input multi-output (MIMO) compensator, which uses the blower/fan power and cathode inlet temperature as actuators. The usable power of the fuel cell (FC) is maximized by limiting the air flow rate deliberately when an increase in power is demanded. Possible rate bounds on the cathode inlet temperature are also modeled. These bounds could represent the physical limitations (due to slow dynamics of heat exchangers) and/or a control concept for accommodating the power saving objective. Applying proper limits to the amplitude and rate of the actuator signals, and incorporating antiwindup (AW) techniques, can raise the net power of the FC by 16% with negligible effects on the spatial temperature profile.

Direct methanol fuel cells (DMFC) are typically supplied under pressure or capillary action with a solution of methanol in water optimized for the best specific power and power density at an operating temperature of about 60 °C. Methanol and water consumption at the anode together with water and methanol losses through membrane due to crossover create an imbalance over time so the fuel concentration at the anode drifts from the optimal ratio. In the present study, we demonstrate a DMFC with a means for continuous adjustment of water and methanol content in the anode fuel mixture of an air-breathing DMFC to maintain the optimal concentration for maximum and continuous power. Two types of piezoelectric micropumps were programmed to deliver the two liquids at the designated rate to maintain optimal concentration at the anode during discharge. The micropumps operate over a wide range of temperature, can be easily reprogrammed and can operate in any orientation. A study of performance at different current densities showed that at 100 mA/cm 2 , the self-contained, free convection, air-breathing cell delivers 31.6 mW/cm 2 of electrode surface with thermal equilibrium reached at 52 °C. The micropumps and controllers consume only 2.6% of this power during 43 h of continuous unattended operation. Methanol utilization is 1.83 Wh cm −3 .

This work defines and implements a technique to predict water activity in proton exchange membrane fuel cell. This technique is based on the electrochemical impedance spectroscopy (EIS) as sensor and adaptive neuro-fuzzy inference system (ANFIS) as estimator. For this purpose, a proton exchange membrane fuel cell (PEMFC) model has been proposed to study the performances of the fuel cell for different operating conditions where the simulation model for water activity behavior is in the proposed structure. The technique based on ANFIS predicts the PEM fuel cell relative humidity (RH) from the EIS. For creation of ANFIS training and checking database, a new method based on factorial design of experimental is used. To check the proposed technique, the ANFIS estimator will be compared with the output humidity relative observation.

This study investigated the combination of the direct and indirect hybrid systems in order to develop a combined hybrid system. In the proposed system, a direct solid oxide fuel cell (SOFC) and gas turbine (GT) hybrid system and an indirect fuel cell cycle were combined and exchanged the heat through a heat exchanger. Several electrochemical, thermal, and thermodynamic calculations were performed in order to achieve more accurate results; then, beside the parametric investigation of the abovementioned hybrid system, the obtained results were compared to the results of direct and indirect hybrid systems and simple GT cycle. Results indicate that the efficiency of the combined hybrid system was between those of the direct and indirect hybrid systems. The electrical efficiency and the overall efficiency of the combined hybrid system were 43% and 59%, respectively. The generation power in the combined hybrid system was higher than that of both other systems, which was the only advantage of using the combined hybrid system. The generation power in the combined hybrid system was higher than that of the direct hybrid system by 16%; accordingly, it is recommended to be used by the systems that are supposed to have high generation power.

Code stability is a matter of concern for three-dimensional (3D) fuel cell models operating both at high current density and at high cell voltage. An idealized mathematical model of a fuel cell should converge for all potentiostatic or galvanostatic boundary conditions ranging from open circuit to closed circuit. Many fail to do so, due to (i) fuel or oxygen starvation causing divergence as local partial pressures and mass fractions of fuel or oxidant fall to near zero and (ii) nonlinearities in the Nernst and Butler–Volmer equations near open-circuit conditions. This paper describes in detail, specific numerical methods used to improve the stability of a previously existing fuel cell performance calculation procedure, at both low and high current densities. Four specific techniques are identified. A straight channel operating as a (i) solid oxide and (ii) polymer electrolyte membrane fuel cell is used to illustrate the efficacy of the modifications.

A method which allows for the comparison of polymer electrolyte fuel cell (PEFC) bipolar plates (BPs) with various channel dimensions is outlined here. It is applied to data from an experiment with different channel and land width and channel depth combinations for interdigitated and parallel designs. Channel and land width and channel depth varied from 0.25 mm to 1 mm on six different BP designs, and two stoichiometries were tested. Each condition was performed three times for repeatability. The method calculates the performance of each condition after accounting for reversible voltage and overpotential changes due to varying pressure and after eliminating ohmic resistance as a variable. In these data, the interdigitated flow field outperformed the parallel flow field. Designs are compared using the BP permeability as a benchmark metric. The method then calculates the area-specific ohmic resistance (ASR) of the cell. It was difficult to draw hard conclusions about changes in the ASR between flow field designs, but there may be more consistent liquid water removal from the gas diffusion layer (GDL) with smaller channel dimensions. It was found that concentration losses seem to be primarily a result of channel width, rather than channel depth.

Proton exchange membrane (PEM) fuel cells suffer noticeable power loss when operated at high power output. This paper proposes a hybridization scheme for a PEM fuel cell/supercapacitor system operating in three different regimes: “Flat,” “Uphill,” and “Downhill.” Transitions among operational regimes are governed by logical statements, which compare operational parameters against threshold values. These threshold values were obtained using a genetic optimization (GO) algorithm. The hybridization problem is analyzed in a simulation environment before the solution is implemented in an actual laboratory prototype. Results and discussion are presented to demonstrate the soundness of the proposed solution. The approach presented in this paper is suitable for applications where sudden changes in power demand occur.

This paper evaluates a state-space methodology of a multi-input multi-output (MIMO) control strategy using a 2 × 2 tightly coupled scenario applied to a physical gas turbine fuel cell hybrid power system. A centralized MIMO controller was preferred compared to a decentralized control approach because previous simulation studies showed that the coupling effect identified during the simultaneous control of the turbine speed and cathode airflow was better minimized. The MIMO controller was developed using a state-space dynamic model of the system that was derived using first-order transfer functions empirically obtained through experimental tests. The controller performance was evaluated in terms of disturbance rejection through perturbations in the gas turbine operation, and setpoint tracking maneuver through turbine speed and cathode airflow steps. The experimental results illustrate that a multicoordination control strategy was able to mitigate the coupling of each actuator to each output during the simultaneous control of the system, and improved the overall system performance during transient conditions. On the other hand, the controller showed different performance during validation in simulation environment compared to validation in the physical facility, which will require a better dynamic modeling of the system for the implementation of future multivariable control strategies.