scholarly journals Asymptotic Analysis for the Effects of Anode Inlet Humidity on the Fastest Power Attenuation Single Cell in a Vehicle Fuel Cell Stack

2018 ◽  
Vol 8 (11) ◽  
pp. 2307 ◽  
Author(s):  
Yongfeng Liu ◽  
Jianhua Gao ◽  
Na Wang ◽  
Shengzhuo Yao
Keyword(s):  
Fuel Cell ◽  
Pressure Drop ◽  
Relative Humidity ◽  
Single Cell ◽  
Geometric Model ◽  
Proton Exchange ◽  
Polarization Curves ◽  
Water Flooding ◽  
Experimental Conditions ◽  
Fuel Cell Stack

A three-dimensional and isothermal anode relative humidity (ARH) model is presented and used to study the anode inlet humidity effects on the fastest power attenuation single cell in a vehicle fuel cell stack. The ARH model is based on the phenomenon that the anode is more sensitive than the cathode to water flooding. The pressure drop is considered in the ARH model, and saturation pressure is established by a pressure drop. Based on the pressure drop and relative humidity, simulations and tests are completed. First, the geometric model and computational grids are established, based on real structure of the proton exchange membrane fuel cell (PEMFC). Second, single cell distribution in the stack, test schematic and experimental conditions are demonstrated. Finally, polarization curves with 10 cells are displayed and discussed under these conditions that working temperature 70 °C, and diverse relative humidity (40%, 55%, 70%, 85%, and 100%). The test results of 34 cm2 fuel cell stack are compared against simulation results. The results show that C10 (the single cell with the farthest distance from the gas inlet) power attenuation is the fastest and that its performance is the poorest under the experimental conditions. The polarization curves predicted by the ARH model indicate fairly good coherence with the experimental results, compared against the Fluent original model. The ARH model calculation deviation is 28% less than the Fluent model at 360 mA·cm−2 for a relative humidity of 85%. The current density distribution is almost uniform, and membrane water content is negatively affected by high humidity.

Observation of Pressure Drop Behavior in an Operating Fuel Cell Stack

2005 ◽  
Author(s):  
Frano Barbir ◽  
Haluk Gorgun ◽  
Xinting Wang
Keyword(s):  
Fuel Cell ◽  
Pressure Drop ◽  
Proton Exchange Membrane ◽  
Proton Exchange ◽  
Cathode Side ◽  
Fuel Cell Stack ◽  
Flow Through ◽  
Drying Conditions ◽  
Exchange Membrane ◽  
The Relationship

Pressure drop on the cathode side of a PEM (Proton Exchange Membrane) fuel cell stack has been studied and used as a diagnostic tool. Since the Reynolds number at the beginning of the flow field channel was <250, the flow through the channel is laminar, and the relationship between the pressure drop and the flow rate is linear. Some departure from linearity was observed when water was either introduced in the stack or produced inside the stack in the electrochemical reaction. By monitoring the pressure drop in conjunction with the cell resistance in an operational fuel cell stack, it was possible to diagnose either flooding or drying conditions inside the stack.

Analysis of Pressure Drop and Water Flooding of Two-Phase Flow Along Channels for a PEM Fuel Cell System

2009 ◽  
Author(s):  
Jinglin He ◽  
Song-Yul Choe ◽  
Chang-Ouk Hong
Keyword(s):  
Fuel Cell ◽  
Pressure Drop ◽  
Relative Humidity ◽  
Liquid Water ◽  
Water Distribution ◽  
Gas Flow ◽  
Pem Fuel Cell ◽  
Cell System ◽  
Water Flooding ◽  
Two Phase

The flow in gas flow channels of an operating polymer electrolyte membrane (PEM) fuel cell has a two-phase characteristic that includes air, water vapor and liquid water and significantly affects the water flooding, pressure distribution along the channels, and subsequently the performance of the cell and system. Presence of liquid water in channels prevents transport of the reactants to the catalysts and increases the pressure difference between the inlet and outlet of channels, which leads to high parasitic power of pumps used in air and fuel supply systems. We propose a model that enables prediction of pressure drop and liquid water distribution along channels and analysis of water flooding in an operating fuel cell. The model was developed based on a gas-liquid two-phase separated flow that considers the variations of gas pressure, mass flow rate, relative humidity, viscosity, void fraction, and density along the channels on both sides. Effects of operating parameters that include stoichoimetric ratio, relative humidity, and inlet pressure on the pressure drop and water flooding along the channels were analyzed.

scholarly journals Single cell induced starvation in a high temperature proton exchange membrane fuel cell stack

2019 ◽  
Vol 250 ◽  
pp. 1176-1189 ◽  
Author(s):  
Cinthia Alegre ◽  
Antonio Lozano ◽  
Ángel Pérez Manso ◽  
Laura Álvarez-Manuel ◽  
Florencio Fernández Marzo ◽  
...  
Keyword(s):  
High Temperature ◽  
Fuel Cell ◽  
Single Cell ◽  
Proton Exchange Membrane ◽  
Proton Exchange ◽  
Fuel Cell Stack ◽  
Exchange Membrane

ac Impedance Study of a Proton Exchange Membrane Fuel Cell Stack Under Various Loading Conditions

2010 ◽  
Vol 7 (3) ◽  
Author(s):  
N. V. Dale ◽  
M. D. Mann ◽  
H. Salehfar ◽  
A. M. Dhirde ◽  
T. Han
Keyword(s):  
Fuel Cell ◽  
Single Cell ◽  
Proton Exchange Membrane ◽  
Low Frequency ◽  
Impedance Analysis ◽  
Pem Fuel Cell ◽  
Ac Impedance ◽  
Proton Exchange ◽  
Fuel Cell Stack ◽  
Exchange Membrane

This paper presents the ac impedance study and analysis of a proton exchange membrane (PEM) fuel cell operated under various loading conditions. Ballard’s 1.2 kW Nexa™ fuel cell used for this study is integrated with a control system. The PEM fuel cell stack was operated using room air and pure hydrogen (99.995%) as input. Impedance data were collected for the fuel cell to study the behavior of the stack and groups of cells under various loads. Single cell impedance analysis was also performed for individual cells placed at different locations in the stack. The ac impedance analysis, also known as electrochemical impedance analysis, showed low frequency inductive effects and mass transport losses due to liquid water accumulation at high current densities. Results show that the stack run time to achieve steady state for impedance measurements is important. Using impedance plots, the average Ohmic resistance for the whole stack was estimated to be 41 mΩ, the same value obtained when summing the resistance value of all individual cells. Impedance analysis for groups of cells at different locations in the stack shows changes in both polarization resistance and capacitive component only in the low frequency region. At high frequencies, single cell inductive and capacitive behavior varied as a function of location in the stack. The effects of artifacts on the high frequency loop and on the high and low frequency intercept loops are also discussed.

Numerical Modeling of Proton Exchange Membrane Fuel Cell With Considering Thermal and Relative Humidity Effects on the Cell Performance

2006 ◽  
Vol 3 (3) ◽  
pp. 292-302 ◽  
Author(s):  
Pei-Hung Chi ◽  
Fang-Bor Weng ◽  
Ay Su ◽  
Shih-Hung Chan
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Fuel Cell ◽  
Relative Humidity ◽  
Proton Exchange Membrane ◽  
Thermal Field ◽  
Proton Exchange ◽  
Cell Performance ◽  
Water Flooding ◽  
Exchange Membrane

A three-dimensional (3D) model has been developed to simulate proton exchange membrane fuel cells. The model accounts simultaneously for electrochemical kinetics, current distribution, hydrodynamics, and multi-components transport. A single set of conservation equations of mass, momentum, energy, species, and electric current are developed and numerically solved using a finite-volume-based computational fluid dynamics technique (by computational fluid dynamics ACE+ commercial code). The physical model is presented for a 5cm×4.92cm×0.4479cm 3D geometry test cell with serpentine channels and counter flow. Subsequently, the model is applied to explore cell temperature effects in the cell environment with different relative humidity of inlet. The numerical model is validated and agreed well with the experimental data. The nonuniformity of thermal and water-saturation distributions is calculated and analyzed as well as its influence on the cell performance. As the cell is operated at low voltages (or high current densities), the thermal field of fuel cell tends to be nonuniform and exists locally in hot spots. The mechanism of thermal field and water content interacted with membrane dehydration and cathode water flooding will be discussed and revealed their influences on the cell performance, stability and degradation will be revealed.

Fuel Cell Performance Improvements Using Cell-to-Cell Flow Distribution Control

2004 ◽  
Author(s):  
J. Peter Hensel ◽  
Randall S. Gemmen ◽  
Brian J. Hetzer ◽  
Jimmy D. Thornton ◽  
Jeffrey S. Vipperman ◽  
...  
Keyword(s):  
Fuel Cell ◽  
Single Cell ◽  
Proton Exchange Membrane ◽  
Flow Distribution ◽  
Proton Exchange ◽  
Development Effort ◽  
Fuel Cell Stack ◽  
Fuel Cell Performance ◽  
Performance Improvements ◽  
Fuel Flow

Balanced flow distribution to each cell in a fuel cell stack plays a significant role in the stack being able to operate at maximum capability and efficiency. This paper discusses the performance improvements in proton exchange membrane fuel cell stacks that can be obtained by using cell-to-cell flow distribution control. In a specially instrumented four-cell stack that employs needle valves to externally control the air and fuel flows to each cell, fuel to a single cell was reduced. The V-I curves collected under these conditions (unbalanced) are compared to curves collected when the fuel flow to each cell was equal (balanced). Reducing the fuel flow to a single cell by 30% decreased the V-I curve cutoff load by 8.5% — demonstrating the negative effect that unbalanced fuel flows can have on stack performance. Typical fuel cell stacks have no dynamic means to keep flows in the stack balanced between the cells, but this work indicates that flow balancing among cells can extend the V-I curve for a fuel cell to higher current values, allowing fuel cell stacks to operate reliably at higher loading and fuel utilizations. Plans to use novel, custom-built micro-valves to dynamically balance flow to individual cells in a fuel cell stack are being pursued as a result of this work, and the status of this development effort is provided.

Lowering the Pressure Drop and Cost of a Proton Exchange Membrane Fuel Cell by Flow Field Plate Design

2020 ◽  
Vol 34 (7) ◽  
pp. 8857-8863
Author(s):  
Yongfeng Liu ◽  
Shijie Bai ◽  
Ping Wei ◽  
Pucheng Pei ◽  
Shengzhuo Yao ◽  
...  
Keyword(s):  
Fuel Cell ◽  
Pressure Drop ◽  
Flow Field ◽  
Proton Exchange Membrane ◽  
Proton Exchange ◽  
Field Plate ◽  
Plate Design ◽  
Exchange Membrane

scholarly journals Experimental investigation on water-injected twin-screw compressor for fuel cell humidification

2012 ◽  
Vol 226 (12) ◽  
pp. 2925-2932 ◽  
Author(s):  
Talal Ous ◽  
Elvedin Mujic ◽  
Nikola Stosic
Keyword(s):  
Fuel Cell ◽  
Relative Humidity ◽  
Constant Pressure ◽  
Water Injection ◽  
Injection Rate ◽  
Fuel Cell Stack ◽  
Balance Of Plant ◽  
Air Supply ◽  
Twin Screw ◽  
Mass Flow Rates

Water injection in twin-screw compressors was examined in order to develop effective humidification and cooling schemes for fuel cell stacks as well as cooling for compressors. The temperature and the relative humidity of the air at suction and exhaust of the compressor were monitored under constant pressure and water injection rate and at variable compressor operating speeds. The experimental results showed that the relative humidity of the outlet air was increased by the water injection. The injection tends to have more effect on humidity at low operating speeds/mass flow rates. Further humidification can be achieved at higher speeds as a higher evaporation rate becomes available. It was also found that the rate of power produced by the fuel cell stack was higher than the rate used to run the compressor for the same amount of air supplied. The efficiency of the balance of plant was, therefore, higher when more air is delivered to the stack. However, this increase in the air supply needs additional subsystems for further humidification/cooling of the balance-of-plant system.

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