4 - 1/30/2011 MEM 415 FUEL CELL ENGINES - Lecture #4...

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1/30/2011 1 -- Lecture #4 -- MEM 415– FUEL CELL ENGINES THERMODYNAMICS AND POLARIZATION MEM 415– Lecture #4 Dr. E. Caglan Kumbur Assistant Professor of Mechanical Engineering Office: Curtis 160 Ph: 215.895.5871 e-mail: eck32@drexel.edu -- Jan 31, 2011 -- Announcements/Comments… ! How was the homework? ! HW# 1 and 2 solutions are posted online. ! Test #1 will be in the 5 th week ( Feb 7, Monday ) Today… Test will start at 2:00 PM. So come on time !!! ! Did you read Chapter 1 and 2 in your book? ! Summary of Electrochemistry ! Thermodynamics and Polarization ! Sample Problems MEM 415– Lecture #4
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1/30/2011 2 What will be on the Test ? The test will be closed book, closed notes , with one sheet of 8 1/2 x 11” paper (only one side allowed) as a crib sheet allowed, and will be turned in with the quiz. It will essentially cover all material from class through today. Most of the questions will be from Chapter 1 and 2 of your text book . So read these chapters. Bring your calculator !!! 1) Read over HW#1 and 2- Solutions are posted! 2) Read Chapter 1 and 2, as well as review your lecture notes. 3) Fuel cell types, challenges, advantages/disadvantages. 4) Basic definitions of electrochemistry, etc. 5) Galvanic/electrolytic cells, Units 6) Triple-phase boundary, components, functions and requirements of each portion of the cell 7) Faraday’s law, how to find tank size, etc. , flow rates of constituents, production rates, cell efficiencies 8) Stoichiometry, fuel utilization efficiency, faradic efficiency 9) Polarization curve – what are the various regions and what dominates losses in them, waste heat, useful power, ohmic, activation, and concentration regions etc. 10) How to find E o , E oo , h, and other properties. MEM 415– Lecture #4 Summary Summary– Cell Potential Cell Potential The potential to convert chemical bond energy into electrical power is proportional to the difference in the potential (voltage) between the electrodes V cathode Flow rate over the falls ! current V anode V cell =V cathode -V anode Standard Reference: Standard hydrogen electrode (SHE) = 0.0 V Since the voltage of a given reaction is a measure of potential energy, it must be referenced to a standard baseline, selected as an arbitrary zero-voltage point. The standard one commonly used is the standard hydrogen electrode (SHE ). Height x Mass Flow Rate MEM 415– Lecture #4
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1/30/2011 3 Summary: Voltage Summary: Voltage --- --- Electrode Potential Electrode Potential For PEM fuel cells, For a complete cell redox reaction, the standard cell voltage is anode potential = 0 V E cell = “ + ” Galvanic (Energy Producing). e.g. Batteries, Fuel cells E cell = “ - ” Electrolytic (Energy Consuming). e.g. Electrolysis, Electroplating Sum of oxidation and reduction reaction potentials : For PEM fuel cells (hydrogen and oxygen as fuel): 0 Reduction Reaction (Given as +1.23 V) E max =1.23 V at Open-Circuit Voltage (OCV) At OCV, there is no current, so maximum potential can be achieved MEM 415– Lecture #4 Summary: Faraday’s Laws Michael Faraday’s Laws (1830): 1. For a specific quantity of charge passed (C), the masses of the products 2. The amount of product formed or reactant consumed is directly
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This note was uploaded on 04/26/2011 for the course MEM 415 taught by Professor Kumbur,emin during the Spring '11 term at Drexel.

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4 - 1/30/2011 MEM 415 FUEL CELL ENGINES - Lecture #4...

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