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Tech Front: Big Fuel Cell Breakthrough is at the Nano Level

 

A development in the real-time observation of fuel cell catalyst degradation could be the breakthrough that leads to the creation of more efficient and durable fuel cell stacks.

Toyota Motor Corp. (Toyota City, Japan) and the the Japan Fine Ceramics Center (JFCC; Nagoya, Japan) have developed a new technique that allows monitoring of the behavior of nanometer-sized particles of platinum during chemical reactions in fuel cells. This allows the processes leading to reduced catalytic reactivity to be observed.

Platinum is an essential catalyst by which the chemical reactions between hydrogen and oxygen produce electricity in fuel cell stacks. Reduced reactivity results when platinum nanoparticles increase in size and decrease in surface area. Up until now, however, it has not been possible to observe the processes leading to this coarsening effect, making it difficult to analyze the root causes.
Photo sequence shows how platinum nanoparticle increase in size over time while catalyzing.
It is believed that this new observation method will enable discovery of the points on the carbon carrier where platinum coarsens, as well as helping determine the level of voltage output during the coarsening process. The method is also expected to help determine the different characteristics of various types of carrier materials. All of these analytical tools should provide direction to research aimed at improving the performance and durability of the platinum catalyst, and of the fuel cell stack.

Fuel cells generate electricity through the chemical reaction of onboard hydrogen gas with airborne oxygen. A fuel cell can have more than one cell which generates electricity through the chemical reaction between each oxygen cathode and hydrogen anode, with water produced as a byproduct.

During the chemical reaction, hydrogen molecules are separated into electrons and hydrogen ions at the hydrogen anode, where the platinum catalyst strips away the electrons from the hydrogen molecule. The electrons travel to the oxygen cathode, generating electricity to power the motor. Meanwhile, the hydrogen ions cross a polymer membrane to reach the oxygen cathode, where water is produced as a byproduct of hydrogen ions and electrons being exposed to airborne oxygen. Platinum also functions as the catalyst for this reaction.

Platinum, a rare precious metal, is essential for electricity generation in fuel cells, playing a vital role in increasing fuel cell electricity generation efficiency.


UGA Researchers Develop New Way to Manufacture Nanofibers

Researchers at the University of Georgia (UGA; Athens) have developed an inexpensive way to manufacture extraordinarily thin polymer strings commonly known as nanofibers. The method—dubbed “magnetospinning” by the researchers—is said to provide a simple, scalable and safe means for producing very large quantities of nanofibers that can be embedded with a multitude of materials, including live cells and drugs.

Nanofibers are less than 100 nm—thousands of times thinner than a human hair—and used in the manufacture of fuel cells, batteries, filters and light-emitting screens as well as by medical researchers for wound dressings, tissue regeneration, drug testing, stem cell therapies and the delivery of drugs directly to the site of infection. They can be made from natural materials like proteins or from human-made substances, including biodegradable materials.

According to Sergiy Minko, study co-author and the Georgia Power Professor of Polymers, Fibers and Textiles in UGA’s College of Family and Consumer Sciences, the new process makes it possible to manufacture nanofibers of high quality without using expensive equipment. Lowering the cost of manufacture will allow businesses and researchers to use nanofibers in new ways without busting their budgets.

The most common nanofiber manufacturing technique to date is called electrospinning. It uses high-voltage electricity and specially designed equipment to produce the polymer strings. Such equipment requires lots of training in order to be used safely and effectively. In contrast, Minko told UGA that for magnetospinning all one really needs is a magnet, a small motor and a syringe, and that a simple lab setup can produce hundreds of yards of nanofiber in seconds.

UGA has a video of the process at https://youtube/CwxkAr74QQc.



SME Tech Papers: Learn More & Do More

Energy-Wise Sustainability
The US National Institute of Standards and Technology (NIST; Gaithersburg, MD) Manufacturing Extension Partnership (MEP) site (www.nist.gov/mep) describes a sustainable approach to manufacturing as “one that merges environmental, societal and economic concerns. Continual improvement is necessary in these three areas in order to secure the future of companies, communities, supply chains and the environment…. Companies that commit to implementing eco-friendly changes find themselves with lower operating costs, access to new markets and a more profitable enterprise.”

MEP sustainability programs include E3 – Economy, Energy, and Environment, a federal-local coordinated effort that helps manufacturers assess production processes and assists with the implementation of energy-saving projects, and the Building Construction Technology Extension Pilot (BCTEP), which focuses on training building operations staff to retune energy systems in smaller commercial and industrial buildings. Commercial buildings account for almost 20% of the total US energy consumption, with 10–30% of the energy used wasted due to improper and inefficient operations.

Energy analysis and optimization is an ongoing process. A novel energy demand modeling approach for CNC machining based on function blocks is described in a paper by Tao Peng, Xun Xu and Lihui Wang in SME’s Journal of Manufacturing Systems (http://tinyurl.com/JMS-functionblocks). Among other merits, the approach aids reconfigurability for different modeling tasks, support for distributed machining execution and control and data connection between high-level and low-level data.

Electricity demand response is considered a promising tool to balance the electricity demand and supply during peak periods. The mature research on implementing this concept for residential and commercial buildings has now been extended to manufacturing. In paper #4006 from the 2014 ASME Manufacturing Science and Engineering Conference (MSEC), a simulation-based optimization method is developed to identify the optimal demand response decision for the typical manufacturing systems of multiple machines and buffers.

A framework for addressing the challenges and methods of joint production and energy modeling of sustainable manufacturing systems is discussed in another MSEC 2014 paper (#4068). Detailed research tasks of the framework are on the modeling of production, energy efficiency, electricity demand, cost and demand response decision making. Joint production and energy scheduling problem formulations and the solution technique are discussed, along with applications of the model in system parameter selection, rate plan switching decision making and demand response scheduling.


Process-Oriented Models

Development of a process-oriented design information model for sustainable manufacturing is described by Heng Zhang and colleagues from Syracuse University in a paper presented at the 2014 North American Manufacturing Research Conference (NAMRC; www.sme.org/namrc; paper #4457). The paper proposes a three-layered framework that can evaluate energy consumption for different processes under a generalized information core. The sustainability analysis of a gear design is presented to demonstrate the framework.

Sustainability indicators for discrete manufacturing processes applied to grinding technology are developed by Barbara Linke, Gero Corman, David Dornfeld and Stefan Tönissen in a paper from NAMRC 2013 (published in the Journal of Manufacturing Systems; http://tinyurl.com/JMS-sustain-grind). Simple and relevant sustainability indicators are displayed as a performance profile that is individual to each manufacturing process variant. The whole procedure is executed with a grinding process case study and provides a straightforward method for evaluating sustainability of discrete manufacturing processes.

New concepts for bio-inspired sustainable grinding are developed by Barbara Linke and Jorge Moreno in a paper presented at NAMRC 2014 (paper #4409). Bio-inspired design is one promising and innovative approach to design better products and processes. The authors use bio-inspired design to find new process setups for novel grinding system components to address problems defined through an axiomatic grinding model. Also discussed are bio-inspired ideas for chip transport and tool cleaning, abrasive wear resistance, self sharpening, breaking air barriers, cooling and new process environments.


Modeling the Pillars of Sustainability

Much research has focused on developing structured approaches for considering the economic, environmental and social impacts of sustainability and how to incorporate them into decision-making tools for manufacturing processes and enterprises. Several papers from NAMRC and MSEC have presented various models and frameworks.

A NAMRC 2010 paper (SME Technical Paper TP10PUB108), by Margot J. Hutchins, John S. Gierke and John W. Sutherland, explains that “manufacturing decision makers [routinely] address the economic pillar of sustainability.” In fact, that is the pillar that has been traditionally addressed. Environmental sustainability has gained more attention in recent years, with carbon footprints, life cycle assessments and greenhouse gas emissions scrutinized. To characterize the more challenging social impact of sustainability, two successive surveys of academic, industry and government sustainability experts determined a set of indicators across 30 categories, six social groups and five need levels and how well the proposed indicators addressed a particular category of needs. A third survey, reported in a later paper, would further refine and rank the indicators.

A paper from MSEC 2014 (paper #4105) presents a study on the scope of the currently available manufacturing information models to incorporate sustainability. The authors propose an extension to the Systems Integration for Manufacturing Applications (SIMA) reference architecture model and refer to it as a GreenSIMA architecture. An example was created using the injection molding unit manufacturing process.

At NAMRC 2015 (paper #60), Qais Hatim et al. present a simulation-based methodology of assessing environmental sustainability and productivity for integrated process and production plans. One consideration of the process-planning research was to avoid improving one performance indicator (e.g., energy consumption) at the expense of other ones (such as tool usage). 

 

More than 16,000 papers make up SME’s knowledge collection. See search options for SME Technical Papers (coded as TP…PUB…) at http://tinyurl.com/SearchTPs. Manufacturing practitioners are encouraged to send submissions for possible publication as SME Technical Papers. Contribute your knowledge to help people make things that improve our world! SME membership is not required. Learn more at www.sme.org/techpapers. For more information on NAMRC and MSEC papers,
e-mail publications@sme.org.

 

 This article was first published in the July 2015 edition of Manufacturing Engineering magazine. Click here for PDF


Published Date : 7/1/2015

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