Investigation of Temperature Limitations During Rapid Thermal Cycling of a Micro-Tubular Flame-Assisted Fuel Cell

2020 ◽  
Author(s):  
Ryan J. Milcarek ◽  
Rhushikesh Ghotkar ◽  
Jeongmin Ahn
Keyword(s):  
Fuel Cell ◽  
Thermal Cycling ◽  
Power Density ◽  
Thermal Insulation ◽  
Current Collector ◽  
Operating Conditions ◽  
Slow Heating ◽  
Maximum Temperature ◽  
Sofc Cathode ◽  
Rapid Thermal Cycling

Abstract Despite many efforts and improvements over the last few decades, two of the major challenges facing Solid Oxide Fuel Cells (SOFCs) are slow heating rates to operating conditions (typically < 5 °C.min−1) and a limited ability to thermal cycle (< 200 cycles). Recently a novel hybridized setup that combines a fuel-rich combustion reformer with a SOFC was developed and utilized to investigate rapid heating, cooling and thermal cycling of a micro-Tubular SOFC. The setup places the SOFC directly in the flame and exhaust of the high temperature combustion of methane, which allows for extremely rapid temperature rise in the SOFC. A SOFC with a (La0.8Sr0.2)0.95MnO3-x cathode was tested in the setup, but limitations on air preheating for the cathode resulted in low SOFC cathode temperatures (∼500°C) and low power density. Thermal insulation improved pre-heating of the air delivered to the cathode, increased the SOFC cathode temperature and, when a (La0.60Sr0.40)0.95Co0.20Fe0.80O3-x cathode was applied to the SOFC, resulted in improved power density. After adjusting the thermal insulation, the air temperature near the cathode exceeded ∼750°C during testing. Over 3,000 thermal cycles were conducted at a heating rate exceeding 900°C.min−1 and a cooling rate that exceeded 300°C.min−1. The open circuit voltage was analyzed over the 150 h test and a low degradation rate of ∼0.0008V per 100 cycles per fuel cell was observed. Unlike the previous test, which was conducted at lower temperatures, significant degradation of the current collector was observed during this test. Electrochemical impedance spectroscopy shows that degradation in the SOFC was due to increases in ohmic losses, activation losses at the cathode and increased concentration losses. The setup demonstrates that rapid thermal cycling of micro-Tubular SOFCs can be achieved, but there are limitations on the maximum temperature that can be sustained depending on the current collector.

A Simulation of the Solid Oxide Fuel Cell Electrochemical Light Off Phenomenon

2005 ◽  
Author(s):  
Comas L. Haynes ◽  
J. Chris Ford
Keyword(s):  
Fuel Cell ◽  
Thermal Cycling ◽  
Solid Oxide Fuel Cell ◽  
Heat Generation ◽  
Operating Conditions ◽  
Solid Oxide ◽  
Oxide Fuel ◽  
Cell Potential ◽  
Start Up ◽  
Electrochemical Transport

During latter-stage, “start-up” heating of a solid oxide fuel cell (SOFC) stack to a desired operating temperature, heat may be generated in an accelerating manner during the establishment of electrochemical reactions. This is because a temperature rise in the stack causes an acceleration of electrochemical transport given the typical Arrhenius nature of the electrolyte conductivity. Considering a potentiostatic condition (i.e., prescribed cell potential), symbiosis thus occurs because greater current prevalently leads to greater by-product heat generation, and vice versa. This interplay of the increasing heat generation and electrochemistry is termed “light off”, and an initial model has been developed to characterize this important thermal cycling phenomenon. The results of the simulation begin elucidating the prospect of using cell potential as well as other electrochemical operating conditions (e.g., reactants utilization) as dynamic controls in managing light off transients and possibly mitigating thermal cycling issues.

Effects of Operating Conditions on the Heat Management of a Microscale Fuel Cell

2019 ◽  
Author(s):  
Liyong Sun ◽  
Adam S. Hollinger ◽  
Jun Zhou
Keyword(s):  
Fuel Cells ◽  
Fuel Cell ◽  
Waste Heat ◽  
Heat Removal ◽  
Current Collector ◽  
Ambient Air ◽  
Operating Conditions ◽  
Heat Management ◽  
Fuel Flow ◽  
Fuel Stream

Abstract Higher energy densities and the potential for nearly instantaneous recharging make microscale fuel cells very attractive as power sources for portable technology in comparison with standard battery technology. Heat management is very important to the microscale fuel cells because of the generation of waste heat. Waste heat generated in polymer electrolyte membrane fuel cells includes oxygen reduction reaction in the cathode catalyst, hydrogen oxidation reaction in the anode catalyst, and Ohmic heating in the membrane. A novel microscale fuel cell design is presented here that utilizes a half-membrane electrode assembly. An ANSYS Fluent model is presented to investigate the effects of operating conditions on the heat management of this microscale fuel cell. Five inlet fuel temperatures are 22°C, 40°C, 50°C, 60°C, and 70°C. Two fuel flow rate are 0.3 mL/min and 2 mL/min. The fuel cell is simulated under natural convection and forced convection. The simulations predict thermal profiles throughout this microscale fuel cell design. The exit temperature of fuel stream, oxygen stream and nitrogen stream are obtained to determine the rate of heat removal. Simulation results show that the fuel stream dominates heat removal at room temperature. As inlet fuel temperature increases, the majority of heat removal occurs via convection with the ambient air by the exposed current collector surfaces. The top and bottom current collector removes almost the same amount of heat. The model also shows that the heat transfer through the oxygen channel and nitrogen channel is minimal over the range of inlet fuel temperatures. Increasing fuel flow rate and ambient air flow both increase the heat removal by the exposed current collector surfaces. Ultimately, these simulations can be used to determine design points for best performance and durability in a single-channel microscale fuel cell.

Optimization of the Operating Parameters of a Proton Exchange Membrane Fuel Cell for Maximum Power Density

2005 ◽  
Vol 2 (2) ◽  
pp. 121-135 ◽  
Author(s):  
A. Mawardi ◽  
F. Yang ◽  
R. Pitchumani
Keyword(s):  
Fuel Cells ◽  
Fuel Cell ◽  
Power Density ◽  
Proton Exchange Membrane ◽  
Proton Exchange ◽  
Operating Conditions ◽  
Optimum Operating ◽  
Design Parameters ◽  
Membrane Thickness ◽  
Exchange Membrane

The performance of fuel cells can be significantly improved by using optimum operating conditions that maximize the power density subject to constraints. Despite its significance, relatively scant work is reported in the open literature on the model-assisted optimization of fuel cells. In this paper, a methodology for model-based optimization is presented by considering a one-dimensional nonisothermal description of a fuel cell operating on reformate feed. The numerical model is coupled with a continuous search simulated annealing optimization scheme to determine the optimum solutions for selected process constraints. Optimization results are presented over a range of fuel cell design parameters to assess the effects of membrane thickness, electrode thickness, constraint values, and CO concentration on the optimum operating conditions.

Dynamic Modelling and Controls of an Air Supply System for In-Flight Proton Exchange Membrane Fuel Cells (PEM-FC)

2007 ◽  
Author(s):  
Lukas P. Barchewitz ◽  
Joerg R. Seume
Keyword(s):  
Fuel Cells ◽  
Fuel Cell ◽  
Power Density ◽  
Supply System ◽  
Operating Conditions ◽  
Design Parameters ◽  
Radial Turbine ◽  
Air Supply ◽  
Exchange Membrane ◽  
Turbomachinery Design

To cover the increasing demand of on-board electrical power and for further reduction of emissions, the conventional auxiliary power unit (APU) may be replaced by a fuel cell system with an expected efficiency increase of 25% to 50% when compared to start-of-the-art GT-APU. The main components of an in-flight FC system are a compressor-turbine unit, a kerosene reformer, and the fuel cell. Polymer exchange membrane fuel cells (PEM-FC) may be favored because of their currently advanced level of development, their high power density and the available liquid water in the cathode-off gases which can be used as service water on-board. Transient requirements may have significant impact on system design and operating range and will therefore be addressed in this paper. During in-flight operation, air has to be compressed from the ambient to a pressure near standard conditions, which allows the application of state-of-the-art PEM-FC and ensures a constant power density independent from the operating altitude. A centrifugal compressor is chosen for pressurization of the system and is powered by a radial turbine, which allows autonomous operation at cruising altitude without external power. For off-design operation and transients, electric support from the PEM-FC is necessary, see [1]. The radial turbine itself is run by the hot exhaust gases from a post-combustor using the remaining energy in the cathode off-gases. A thorough trade-off between suitable compressor techniques for the air supply system was carried out in [1]. Turbomachinery revealed to be favourable for the PEM air supply system due to their low specific weight and high efficiency. The air supply system resembles the turbocharger for a combustion engine (Fig. 1), which represents a good starting point for a successful integration into the flight environment and further development due to known technology. Based on a turbomachinery design which satisfies the system requirements, the dynamic behavior of the air supply system is analyzed when coupled to the PEM fuel cell. The main focus is on the detection of sensitive system parameters causing system response delay or critical operating conditions. The present paper suggests system features, turbomachinery design parameters and controller types which achieve inherent stability and fast response of the air supply system throughout the entire flight envelope.

Metal-supported solid oxide fuel cell membranes for rapid thermal cycling

2005 ◽  
Vol 176 (5-6) ◽  
pp. 443-449 ◽  
Author(s):  
Y MATUS ◽  
L DEJONGHE ◽  
C JACOBSON ◽  
S VISCO
Keyword(s):  
Fuel Cell ◽  
Thermal Cycling ◽  
Solid Oxide Fuel Cell ◽  
Cell Membranes ◽  
Solid Oxide ◽  
Oxide Fuel ◽  
Fuel Cell Membranes ◽  
Rapid Thermal Cycling

scholarly journals High-power density monolithic fuel cell stack

2021 ◽  
Author(s):  
Steven Pirou ◽  
Belma Talic ◽  
Karen Brodersen ◽  
Anne Hauch ◽  
Henrik Frandsen ◽  
...  
Keyword(s):  
Fuel Cell ◽  
Thermal Cycling ◽  
Power Density ◽  
High Power ◽  
Internal Combustion Engines ◽  
High Efficiency ◽  
Three Dimensional ◽  
Limited Range ◽  
Attractive Alternative ◽  
High Power Density

Abstract The transportation sector is currently undergoing a technology shift from internal combustion engines to electric motors powered by batteries. However, their limited range and long charging times limit wide-spread adoption. Electrified transportation powered by solid oxide fuel cells (SOFCs) offer an attractive alternative especially for heavy freight and long-range transportation, as this technology can provide high-efficiency and flexible fuel choices. Thus far, the technology is mostly used for stationary applications owing to the high operating temperature, low volumetric and gravimetric power density, and poor robustness towards thermal cycling and mechanical vibrations of conventional ceramic-based cells. Here, we present a novel metal-based monolithic fuel cell design to overcome these issues. Highly cost-competitive and scalable manufacturing methods are employed for fabrication, and only a single heat treatment is required, as opposed to two or three for conventional SOFCs. The design is further optimised through three-dimensional multiphysics modelling, nanoparticle infiltration, and corrosion-mitigating treatments. The monolithic fuel cell shows exceptionally high power density (5.6 kW/L) and excellent thermal cycling robustness, revealing the vast potential of SOFC technology for transport applications.

The Design and Integration of the Rolls-Royce Fuel Cell Systems 1MW SOFC

2005 ◽  
Author(s):  
Gerry Agnew ◽  
Michele Bozzolo ◽  
Robert R. Moritz ◽  
Steve Berenyi
Keyword(s):  
Fuel Cell ◽  
Power Density ◽  
Design Process ◽  
Hybrid System ◽  
Cell Hybrid ◽  
Operating Conditions ◽  
Modular Architecture ◽  
Cell Systems ◽  
System A ◽  
Extensive Range

Rolls-Royce Fuel Cell Systems (RRFCS) is developing a 1MW fuel cell hybrid system package, supported by a prototype demonstration of a 250kW generator module in 2006. The ongoing design process has been focused from the early stages towards simplicity as a key to achieve the demanding cost targets for an effective market entry. This paper describes how the specifically designed components are being integrated as a system. A description of the progress against the demonstration plan is provided. The baseline plant is expected to provide excellent part-load performance in an extensive range of operating conditions, while a modular architecture guarantees availability and reliability. Finally, opportunities for further increases in efficiency and power density are discussed, as the technology evolves towards a next generation product.

scholarly journals In Situ Monitoring of Corrosion under Insulation Using Electrochemical and Mass Loss Measurements

2022 ◽  
Vol 2022 ◽  
pp. 1-12
Author(s):  
Mingzhang Yang ◽  
Jing Liu
Keyword(s):  
Thermal Cycling ◽  
Mass Loss ◽  
Thermal Insulation ◽  
Polarization Resistance ◽  
Operating Conditions ◽  
In Situ Monitoring ◽  
Pipe Surface ◽  
Eis Measurements ◽  
Corrosion Under Insulation

Corrosion under insulation (CUI) refers to the external corrosion of piping and vessels when they are encapsulated in thermal insulation. To date, very limited information (especially electrochemical data) is available for these “difficult-to-test” CUI conditions. This study was aimed at developing a novel electrochemical sensing method for in situ CUI monitoring and analysis. Pt-coated Ti wires were used to assemble a three-electrode electrochemical cell over a pipe surface covered by thermal insulation. The CUI behavior of X70 carbon steel (CS) and 304 stainless steel (SS) under various operating conditions was investigated using mass loss, linear polarization resistance (LPR), and electrochemical impedance spectroscopy (EIS) measurements. It was found that both the consecutive wet and dry cycles and cyclic temperatures accelerated the progression of CUI. LPR and EIS measurements revealed that the accelerated CUI by thermal cycling was due to the reduced polarization resistance and deteriorated corrosion film. Enhanced pitting corrosion was observed on all tested samples after thermal cycling conditions, especially for CS samples. The proposed electrochemical technique demonstrated the ability to obtain comparable corrosion rates to conventional mass loss data. In addition to its potential for in situ CUI monitoring, this design could be further applied to rank alloys, coatings, and inhibitors under more complex exposure conditions.

scholarly journals Performance Analysis of a PEM Fuel Cell Stack Having 150 cm2 Active Layer by Using Design of Experiments (DOE)

2020 ◽  
Vol 162 ◽  
pp. 01004
Author(s):  
Elif Eker Kahveci ◽  
Imdat Taymaz
Keyword(s):  
Fuel Cell ◽  
Power Density ◽  
Active Layer ◽  
Flow Rate ◽  
Polymer Electrolyte Membrane ◽  
Operating Conditions ◽  
Cell Temperature ◽  
Fuel Cell Stack ◽  
Electrolyte Membrane ◽  
Optimization Study

In this study, the effects of operating parameters on power density of a 3-cell PEMFC (Polymer Electrolyte Membrane Fuel Cell) stack with serpentine flow channels having 150 cm2 total active layer have been examined experimentally. Desing Expert, which is the experimental design program (trial version) was used, and the data obtained as a result of the experiments were analyzed by entering this program. A total of 25 experiments were carried out according to the design created with the data entered into the program within the specified operating conditions range. The independent variables were entered which are cell temperature, humidification temperature, H2 flow rate and O2 flow rate, and the response is the power density. In this study, the hydrophobic cell stack which has the highest cell performance of which was previous studies results was used. In the optimization study, keeping the power density and maximum H2 flow to a minimum, the most suitable values are cell temperature 57.826°C, humidification temperature 56.151°C, O2 flow 1.587 L/min. Finally 432.398 mW/cm2 power density value was obtained under these operating conditions.

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