Spelling suggestions: "subject:"croton exchange membrane"" "subject:"kroton exchange membrane""
31 |
Membrane degradation studies in PEMFCsChen, Cheng. January 2009 (has links)
Thesis (Ph.D)--Chemical Engineering, Georgia Institute of Technology, 2010. / Committee Chair: Fuller, Thomas; Committee Member: Beckham, Haskell; Committee Member: Hess, Dennis; Committee Member: Koros, William; Committee Member: Meredith, Carson. Part of the SMARTech Electronic Thesis and Dissertation Collection.
|
32 |
Experimental and Modelling Studies of Cold Start Processes in Proton Exchange Membrane Fuel CellsJiao, Kui January 2011 (has links)
Proton exchange membrane fuel cell (PEMFC) has been considered as one of the most promising energy conversion devices for the future in automotive applications. One of the major technical challenges for the commercialization of PEMFC is the effective start-up from subzero temperatures, often referred to as “cold start”. The major problem of PEMFC cold start is that the product water freezes when the temperature inside the PEMFC is lower than the freezing point. If the catalyst layer (CL) is fully occupied by ice before the cell temperature rises above the freezing point, the electrochemical reaction may stop due to the blockage of the reaction sites. However, only a few of the previous PEMFC studies paid attention to cold start. Hence, understanding the ice formation mechanisms and optimizing the design and operational strategies for PEMFC cold start are critically important.
In this research, an experimental setup for the cold start testing with simultaneous measurement of current and temperature distributions is designed and built; a one-dimensional (1D) analytical model for quick estimate of purging durations before the cold start processes is formulated; and a comprehensive three-dimensional (3D) PEMFC cold start model is developed. The unique feature of the cold start experiment is the inclusion of the simultaneous measurement of current and temperature distributions. Since most of the previous numerical models are limited to either 1D or two-dimensional (2D) or 3D but only considering a section of the entire cell due to computational requirement, the measured distribution data are critically important to better understand the PEMFC cold start characteristics. With a full set of conservation equations, the 3D model comprehensively accounts for the various transport phenomena during the cold start processes. The unique feature of this model is the inclusion of: (i) the water freezing in the membrane electrolyte and its effects on the membrane conductivity; (ii) the non-equilibrium mass transfer between the water in the ionomer and the water (vapour, liquid and ice) in the pore region of the CL; and (iii) both the water freezing and melting in the CL and gas diffusion layer (GDL). This model therefore provides the fundamental framework for the future top-down multi-dimensional multiphase modelling of PEMFC. The experimental and numerical results elaborate the ice formation mechanisms and other important transport phenomena during the PEMFC cold start processes. The effects of the various cell designs, operating conditions and external heating methods on the cold start performance are studied. Independent tests are carried out to identify and optimize the important design and operational parameters.
|
33 |
Investigations Of New Horizons On H2/o2 Proton Exchange Membrane Fuel CellsYazaydin, Ahmet Ozgur 01 January 2003 (has links) (PDF)
Proton exchange membrane fuel cells are electrochemical devices which
convert the chemical energy of hydrogen into electrical energy with a high
efficiency. They are compact and produce a powerful electric current relative to their
size. Different from the batteries they do not need to be recharged. They operate as
long as the fuel is supplied. Fuel cells, therefore, are considered as one of the most
promising options to replace the conventional power generating systems in the
future.
In this study five PEMFCs / namely EAE1, AOY001, AOY002, AOY003 and
AOY004 were manufactured with different methods and in different structures. A
test station was built to make the performance tests. Performances of the PEMFCs
were compared by comparing the voltage-current (V-i) diagrams obtained during the
initial tests at 25 º / C of fuel cell and gas humidification temperatures. AOY001
showed the best performance among all PEMFCs with a current density of 77.5
mA/cm2 at 0.5 V and it was chosen for further parametric studies where the effect of
different flow rates of H2 and O2 gases, gas humidification and fuel cell temperatures
on the performance were investigated.
It was found that increasing fuel cell and gas humidification temperatures
increased the performance. Excess flow rate of reactant gases had an adverse effect
on the performance. On the other hand increasing the ratio of flow rate of oxygen to
hydrogen had a positive but limited effect. AOY001 delivered a maximum current
density of 183 mA/cm2 at 0.5 V. The highest power obtained was 4.75 W
|
34 |
Design and characterization of nonwoven fabrics for gas diffusion layer in polymer electrolyte membrane fuel cellIsikel, Lale, January 2007 (has links) (PDF)
Thesis (M.S.)--Auburn University, 2007. / Abstract. Vita. Includes bibliographic references (ℓ. 70-74)
|
35 |
Development of polymer electrolyte membranes for fuel cells to be operated at high temperature and low humidityZhou, Zhen. January 2007 (has links)
Thesis (Ph. D.)--Chemistry and Biochemistry, Georgia Institute of Technology, 2007. / Committee Chair: Wong, C.P.; Committee Co-Chair: Liu, Meilin; Committee Member: Barefield, Kent; Committee Member: Collard, David; Committee Member: Fahrni, Christoph.
|
36 |
Zeolite-based micro fuel cells /Kwan, Siu Ming. January 2008 (has links)
Thesis (Ph.D.)--Hong Kong University of Science and Technology, 2008. / Includes bibliographical references (p. 143-163).
|
37 |
Modeling a proton exchange membrane fuel cell stackDeLashmutt, Timothy E. January 2008 (has links)
Thesis (M.S.)--Ohio University, November, 2008. / Title from PDF t.p. Includes bibliographical references.
|
38 |
Characterization of mass transport processes to enable PEM fuel cell start-up from low temperatures /Harris, Daniel I. January 2009 (has links)
Thesis (M.S.)--Rochester Institute of Technology, 2009. / Typescript. Includes bibliographical references (leaves 68-71).
|
39 |
Modeling and control of an automotive fuel cell thermal system /Nolan, John. January 2009 (has links)
Thesis (M.S.)--Rochester Institute of Technology, 2009. / Typescript. Includes bibliographical references (p. 93-95).
|
40 |
Simulation of PEM fuel cells: validation of model and incorporation of humidity dynamicsRodgers, Steven Francis, January 2010 (has links) (PDF)
Thesis (M.S.)--Missouri University of Science and Technology, 2010. / Vita. The entire thesis text is included in file. Title from title screen of thesis/dissertation PDF file (viewed July 29, 2010) Includes bibliographical references (p. 64-67).
|
Page generated in 0.0489 seconds