Abstract
The development of power conversion systems based on fuel cells has been demanding reliability studies since the requirements associated with cost and durability of these technological products have become fundamental to their acceptance by the energy market. The experimental part of the reliability study presented in this work consisted of performing life tests with single proton exchange membrane fuel cells (PEMFCs). The proposed reliability analysis methodology covered the application of qualitative and quantitative techniques. In the qualitative approach, a Failure Mode and Effect Analysis was developed in order to identify and evaluate all potential failures associated with the operation of fuel cells. In the quantitative approach, a statistical analysis was applied to the sample data generated in long-term steady-state tests of these devices. A two-parameter exponential distribution was fitted to data and the maximum likelihood estimate for the mean time to failure (MTTF) of the fuel cells was calculated. It is important to point out that the tests performed under the scope of this study were the first long-term experiments performed with the fuel cells produced in the laboratories of IPEN-CNEN/SP, Brazil. Although the results indicated that fuel cell performance and durability were still at a level below the targets normally established for similar commercial devices, the improvement of the main components of PEMFCs has been the objective of several projects developed at the institute. Thus, the main benefit brought by this study is the proposed methodology, which can be implemented as part of a reliability growth analysis of the fuel cells and can be integrated into the design process of these devices.
Highlights
The increasing global concern with the environment and climate changes has been encouraging scientists and energy companies to search low impact energy sources, high efficiency power generation systems and low polluting automotive vehicles
The results indicated that fuel cell performance and durability were still at a level below the targets normally established for similar commercial devices, the improvement of the main components of proton exchange membrane fuel cells (PEMFCs) has been the objective of several projects developed at the institute
According to the analysis methodology proposed for this study, sample data obtained from the long-term steady-state tests of the PEMFCs were compiled and the results were divided into two main groups: 1) performance of the fuel cells, associated with the observed measures of fuel cell voltage and power density over selected periods of time; and
Summary
The increasing global concern with the environment and climate changes has been encouraging scientists and energy companies to search low impact energy sources, high efficiency power generation systems and low polluting automotive vehicles. This scenario has been favorable to the maturing process of the so-called “hydrogen economy”, in which the concept of the energy conversion system known as “fuel cell” is inserted. The United States of America, Japan, Canada and some European Union countries carry out important programs in this area and establish well defined targets in relation to the application of hydrogen and fuel cell technology to transportation (cars, buses, trains, spaceships, forklifts, etc.), stationary power (low to moderate power level) and portable power (computers, cell phones, etc.). Regarding Brazil, it is expected that this technology, which is associated to a low pollutant emission and high efficiency use of fuel, may take an important role in the planning of its national energy matrix [2]
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