Empirical membrane lifetime model for heavy duty fuel cell systems

Abstract

Heavy duty fuel cells used in transportation system applications such as transit buses expose the fuel cell membranes to conditions that can lead to lifetime-limiting membrane failure via combined chemical and mechanical degradation. Highly durable membranes and reliable predictive models are therefore needed in order to achieve the heavy duty fuel cell lifetime target of 18,000 h. In the present work, an empirical membrane lifetime model was developed based on laboratory data from a suite of accelerated membrane durability tests. The model considers the effects of cell voltage, temperature, oxygen concentration, humidity cycling, humidity level, and platinum in the membrane using inverse power law and exponential relationships within the framework of a general log- Labs where all the TEM testing was done. List of Tables List of Acronyms Chapter 1. IntroductionFuel cells are electrochemical devices that convert chemical energy in fuels into electrical energy directly, providing power generation with high efficiency and low environmental impact [1]. In a fuel cell system unit cells are stacked up next to each other creating an electrically connected stack according to the desired output capacity.The feed stream conditioning, thermal management, and electric power conditioning of the stack is provided by components that belong to the balance of plant.The main components of a fuel cell unit are an anode (negative electrode), cathode (positive electrode) and the electrolyte. Additional components are necessary for assembly of a fuel cell stack such as bipolar plates, flow fields and balance of plant components such as blowers and compressors for fuel supply and product removal, water and temperature management devices, converters, etc. Fuel is fed to the anode, and oxidant is fed to the cathode continuously at the same time. Hydrogen oxidation and oxygen reduction are the electrochemical reactions necessary for splitting the fuel and oxidant into ions and electrons. These reactions take place at electrode triple phase boundaries, which are catalytically active regions where the electrode particles, electrolyte phase, and gas pores intersect [2]. Highly porous electrode surfaces allow efficient diffusion of reactant gases to catalyst sites, and product removal from the fuel cell. Fuel cells are classified according to their electrolyte and fuel. The electrolyte also determines the electrode reactions and the type of ions that pass through the electrolyte.The electrolyte is thin in order to avoid losses caused by ion diffusion due to electrolyte material resistance. The electrolyte also acts as a physical barrier to prevent mixing of fuel and oxidant gas streams [1]. Some common types of fuel cells are the polymer electrolyte fuel cell (PEMFC), solid oxide fuel cell (SOFC), alkaline fuel cell (AFC), phosphoric acid fuel cell (PAFC), and molten carbonate fuel cell (MCFC) [1], [3]. SOFCs offer fuel flexibility, since they are capable of fuel reforming conventional hydrocarbon 2 Commercial Confidential fue...

Web‐Like Interconnected Carbon Networks from NaCl‐Assisted Pyrolysis of ZIF‐8 for Highly Efficient Oxygen Reduction Catalysis

“…Generally speaking, oxygen molecule is reduced either by a 2‐e − process to peroxide, or by a 4‐e − process to water . However, the peroxide generated in the 2‐e − process is harmful to the cell assembly and reduces the cell life . Therefore, ORR catalysts with high selectivity toward the 4‐e − process are preferred.…”

Resilience of Liquid Organic Hydrogen Carrier Based Energy‐Storage Systems

“…Macauley et al. observed that heavy‐duty fuel cells that were used during a project in Whistler, British Columbia, with 50 fuel cell transit busses reached a lifetime of 17 500 h . This is of the order of magnitude of the target of the Department of Energy (DOE) of 18 000 h for the year 2016 for fuel‐cell power plants .…”

“…[47] Manufacturers state lifetimes between 40 000 [48] and 80 000 h. [49] It is, however, crucialt ot ake appropriate maintenance measures with regularc hecks and replacement of wearing parts.I n comparison, lifetimes for fuel cells are reported between 1300 [50] and 87 600 h( 10 years). [50,51] Macauley et al observed that heavy-duty fuel cells that were used during ap roject in Whistler, British Columbia, with 50 fuel cell transit busses reached al ifetime of 17 500 h. [52] This is of the order of magnitude of the target of the Department of Energy (DOE) of 18 000 hfor the year 2016 for fuel-cell powerplants. [53] Manufacturers state lifetimes in the same range.…”

Optimal parameter identification for the proton exchange membrane fuel cell using Satin Bowerbird optimizer

“…[1][2][3][4][5][6][7] High-efficiency type of PEMFC leads to forecasting performance and improve the cell design and all component of the device that combined with it. The power generation process by the fuel cell has performed through electrochemical reactions instead of traditional combustion systems.…”

“…The high current density delivered by PEMFC results in the compressed design, fast answer time, and lightweight. [1][2][3][4][5][6][7] High-efficiency type of PEMFC leads to forecasting performance and improve the cell design and all component of the device that combined with it. From witch precision modeling, the price and time decrease in periods of designing and testing is investigated to obtain the extra advantages.…”