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Cell Temperature (cell + temperature)
Selected AbstractsPolarization characteristics and property distributions of a proton exchange membrane fuel cell under cathode starvation conditionsINTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 10 2010Dongsoo Ko Abstract Property distribution and polarization characteristics of a proton exchange membrane fuel cell (PEMFC) under cathode starvation conditions were investigated numerically and experimentally for a unit cell. The polarization curves of a lab-scale PEMFC were measured with increasing current density for different cell temperatures (40°C, 50°C, and 60°C) at a relative humidity of 100%. To investigate the local temperature, water content and current density on the membrane, and gas velocity in the channel of the PEMFC, numerical studies using the es-pemfc module of the commercial flow solver STAR-CD, which were matched with experimental data, were conducted. Temperature, current density on the membrane, and water content in the MEA were examined to investigate the effect of cell temperature on performance under the cathode starvation condition. At cathode starvation conditions, the performance of a higher cell temperature condition might drop significantly and the mean temperature on the membrane increase abruptly with increasing cell temperature or current density. Copyright © 2009 John Wiley & Sons, Ltd. [source] Exergetic performance analysis of a PEM fuel cellINTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 5 2006M. Ay Abstract In this paper we investigate the effects of thermodynamic irreversibilities on the exergetic performance of proton exchange membrane (PEM) fuel cells as a function of cell operating temperature, pressures of anode and cathode, current density, and membrane thickness. The practical operating conditions are selected to be 3,5 atm for anode and cathode pressures, and 323,353 K for the cell temperatures, respectively. In addition, the membrane thicknesses are chosen as 0.016, 0.018 and 0.02 cm, respectively. Moreover, the current density range of the PEM fuel cell is selected to be 0.01,2.0 A cm,2. It is concluded that exergy efficiency of PEM fuel cell decreases with a rise in membrane thickness and current density, and increases with a rise of cell operating pressure and with a decrease of current density for the same membrane thickness. Thus, it can be said that, in order to increase the exergetic performance of PEM fuel cell, the lower membrane thickness, the lower current density and the higher cell operating pressure should be selected in case PEM fuel cell is operated at constant cell temperature. Copyright © 2005 John Wiley & Sons, Ltd. [source] Formation and optical properties of Cr-doped CdTe/ZnTe nanostructures on ZnTe substrates by molecular beam epitaxyPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 4 2003K. Godo Abstract We study the growth and optical properties of Cr-doped CdTe/ZnTe nanostructures grown on ZnTe (001) substrates by molecular beam epitaxy. In-situ reflection high-energy electron diffraction is used to study the growth processes and strain relaxation behaviors of Cr-doped CdTe quantum dots (QDs). After 4.5,ML deposition, the surface lattice parameter begins to increase remarkably, which indicates that the two-dimensional growth mode is terminated and the CdTe layer grows in a three-dimensional mode. Low temperature photoluminescence spectra of Cr-doped CdTe QDs (Tcr = 900 °C) show a broad emision. With increasing the Cr cell temperature above 1000 °C, the luminescence from CdTe QDs disappears and the broad luminescence at around 1.6 eV becomes dominant. [source] Procedure for determining the uncertainty of photovoltaic module outdoor electrical performance,PROGRESS IN PHOTOVOLTAICS: RESEARCH & APPLICATIONS, Issue 2 2001K. Whitfield This paper sets forth an uncertainty estimation procedure for the measurement of photovoltaic (PV) electrical performance using natural sunlight and calibrated secondary reference cells. The actual test irradiance should be restricted to values between 800 and 1000,W/m2 in order to assume that maximum power varies linearly with irradiance. Only the uncertainty of maximum power at standard test conditions (STC), i.e., 1000,W/m2 plane-of-array irradiance and 25°C cell temperature, is developed in its entirety. The basic uncertainty analysis principles developed herein, however, can be applied to any electrical variable of interest (e.g., short-circuit current, open-circuit voltage and fill factor). Although the equations presented appear cumbersome, they are easily implemented into a computer spreadsheet. Examples of uncertainty analyses are also presented herein to make the concepts more concrete. Published in 2001 by John Wiley & Sons, Ltd. [source] Investigation on the proton exchange membrane water electrolyzer using supported anode catalystASIA-PACIFIC JOURNAL OF CHEMICAL ENGINEERING, Issue 1 2009Sheng Sui Abstract The proton exchange membrane water electrolyzer (PEMWE) was investigated using a novel supported anode catalyst. The supported catalyst for the oxygen evolution reaction (OER) was synthesized by chemical reduction and deposition under ultrasonic dispersion. Transmission electron microscopy (TEM) reveals that iridium (Ir) particles with sizes of about 10,40 nm are mainly dispersed on the outside surface of titanium carbide (TiC). The PEMWE using the supported Ir/TiC (40 wt% Ir) as the anode catalyst shows the best performance among the supported catalysts of three different Ir contents. Increasing the cell temperature in the PEMWE can enhance the activity of the catalyst and lower the over-potential of the electrodes, which can improve the performance of the PEMWE. At a cell temperature of 80 °C and atmospheric pressure, the current densities of the best PEMWE at the potential of 1.8 and 2.0 V are 1002 and 1736 mA/cm2, respectively. Copyright © 2008 Curtin University of Technology and John Wiley & Sons, Ltd. [source] Polarization characteristics and property distributions of a proton exchange membrane fuel cell under cathode starvation conditionsINTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 10 2010Dongsoo Ko Abstract Property distribution and polarization characteristics of a proton exchange membrane fuel cell (PEMFC) under cathode starvation conditions were investigated numerically and experimentally for a unit cell. The polarization curves of a lab-scale PEMFC were measured with increasing current density for different cell temperatures (40°C, 50°C, and 60°C) at a relative humidity of 100%. To investigate the local temperature, water content and current density on the membrane, and gas velocity in the channel of the PEMFC, numerical studies using the es-pemfc module of the commercial flow solver STAR-CD, which were matched with experimental data, were conducted. Temperature, current density on the membrane, and water content in the MEA were examined to investigate the effect of cell temperature on performance under the cathode starvation condition. At cathode starvation conditions, the performance of a higher cell temperature condition might drop significantly and the mean temperature on the membrane increase abruptly with increasing cell temperature or current density. Copyright © 2009 John Wiley & Sons, Ltd. [source] Exergetic performance analysis of a PEM fuel cellINTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 5 2006M. Ay Abstract In this paper we investigate the effects of thermodynamic irreversibilities on the exergetic performance of proton exchange membrane (PEM) fuel cells as a function of cell operating temperature, pressures of anode and cathode, current density, and membrane thickness. The practical operating conditions are selected to be 3,5 atm for anode and cathode pressures, and 323,353 K for the cell temperatures, respectively. In addition, the membrane thicknesses are chosen as 0.016, 0.018 and 0.02 cm, respectively. Moreover, the current density range of the PEM fuel cell is selected to be 0.01,2.0 A cm,2. It is concluded that exergy efficiency of PEM fuel cell decreases with a rise in membrane thickness and current density, and increases with a rise of cell operating pressure and with a decrease of current density for the same membrane thickness. Thus, it can be said that, in order to increase the exergetic performance of PEM fuel cell, the lower membrane thickness, the lower current density and the higher cell operating pressure should be selected in case PEM fuel cell is operated at constant cell temperature. Copyright © 2005 John Wiley & Sons, Ltd. [source] A semi-empirical cell voltage model for polymer electrolyte/methanol systems: Applicability of the group contribution methodJOURNAL OF APPLIED POLYMER SCIENCE, Issue 5 2008Ji Yun Seong Abstract A new group contribution model is established to describe the cell voltage of a direct methanol fuel cell as a function of the current density. The model equation is validated with experimental data over a wide range of methanol concentrations and temperatures. The proposed model focuses on very unfavorable conditions for cell operation, that is, low methanol solution concentrations and relatively low cell temperatures. The proposed group contribution method includes a methanol crossover effect that plays a major role in determining the cell voltage of a direct methanol fuel cell. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source] Numerical model for polymer electrolyte membrane fuel cells with experimental application and validationASIA-PACIFIC JOURNAL OF CHEMICAL ENGINEERING, Issue 1 2009Javier Alonso Mora Abstract The aim of this paper is to present a simple 3D computational model of a polymer electrolyte membrane fuel cell (PEMFC) that simulates over time the heat distribution, energy, and mass balance of the reactant gas flows in the fuel cell including pressure drop, humidity, and liquid water. Although this theoretical model can be adapted to any type of PEMFC, for verification of the model and to present different analysis it has been adapted to a single cell test fixture. The model parameters were adjusted through a series of experimental tests and the model was experimentally validated for a well-defined range of operating conditions: H2/air O2 as reactants, flow rates of 0.5,1.5 SLPM, dew points and cell temperatures of 30,80 °C, currents 0,5 A and with/without water condensation. The model is especially suited for the analysis of liquid water condensation in the reactant channels. A key finding is that the critical current at which liquid water is formed is determined at different flows, temperatures, and humidity. Copyright © 2008 Curtin University of Technology and John Wiley & Sons, Ltd. [source] | ||||||||||