Friday, March 13, 2009
High-Efficiency Generators for Hybrid Vehicles
Free-piston engines could be used to generate electricity as efficiently as, and less expensively than, fuel cells.An unconventional engine design is attracting attention as a potential alternative to hydrogen fuel cells or conventional engines in some hybrid vehicles. Called the free-piston engine, it could be used to generate electricity as efficiently as fuel cells yet cost less.Free-piston engines aren't new: they were invented in the 1920s. But the increased recent focus on hybrid cars has led a growing number of research groups and automakers to start research programs to develop the technology. Unlike in conventional engines, there is no mechanical connection between the piston and a crankshaft (hence the name free-piston). Since the design allows for improved combustion and less friction, the engines could be far more efficient in generating electricity than either conventional generators or newer fuel-cell technology.Having a cheap and efficient way to generate electricity is becoming more important as automakers develop electric vehicles with onboard generators for recharging the battery pack and extending range. Such vehicles, called series plug-in hybrids or extended-range electric vehicles, are to be sold starting in late 2010. (Click here for a comparison of different hybrid and electric vehicle types.) The first will use generators based on conventional engines. But later models could incorporate fuel cells or other unconventional generators, such as free-piston engines.The potential high efficiency of free-piston engines gives them an advantage over conventional generators, and their ability to use a variety of fuels is an advantage over hydrogen fuel cells. What's more, free-piston engines don't require expensive materials such as the platinum catalysts needed in fuel cells, so they could be cheaper too.Automakers such as GM, Lotus, and Volvo have started to investigate the possibility of using such engines in future vehicles. Meanwhile, in the past couple of years, an increasing number of academic research teams have started developing the engines. So far, most have focused on computer simulations. An exception is a research group at Sandia National Laboratory led by Sandia researcher Peter Van Blarigan that has been testing physical components of free-piston engines. He is assembling a complete free-piston engine prototype, a project that he expects to complete within a year.In conventional internal combustion engines, multiple pistons are connected via rods to a crankshaft that, via the transmission, drives the wheels. Free-piston engines do away with the crankshaft: the pistons aren't connected to anything. Instead, two opposing pistons just shuttle back and forth inside a chamber. To generate electricity, the pistons could be equipped with rows of magnets that shuttle past metal coils to create an electrical current.Van Blarigan's experiments suggest that these engines could be 50 percent efficient at generating electricity--close to the efficiency of hydrogen fuel cells and much more efficient than conventional generators. Free-piston engines are efficient in part because they have fewer moving parts than conventional engines do. The engine configuration also makes it practical to tune the engine so that the fuel in a combustion chamber burns very quickly. Faster combustion allows the engine to get more work out of a given amount of fuel, improving efficiency. It can also improve emissions.The free-piston design can also allow the engine to be instantly optimized for different fuels, such as hydrogen, natural gas, ethanol, gasoline, and diesel. Ideally, drivers could use whatever fuel is cheap and readily available.The development of free-piston engines, however, is still at an early stage. "The free-piston has some unique features--simplicity and variable compression--which make it intriguing," says Gary Smyth, the science director of GM's Powertrain Systems Research Lab. "But [they] also pose a number of challenges."Van Blarigan says that one major concern is the sound of the engines: the fast explosions are very loud and will be difficult to muffle. But perhaps the biggest issue is control. In a conventional engine, the movement of the pistons is constrained by the rods and crankshaft, which help even out any variations from cycle to cycle. The free-piston engine is more flexible. That allows for using different fuels, but it makes necessary some sort of active control mechanism to ensure that each cycle is the same: variations could cause poor performance and increased emissions. High-speed computers and the ability to electronically control piston movement in a free-piston generator (via the coils and magnets) could help engineers solve this problem.Whether the engines will be significantly cheaper and more efficient than conventional engines is unclear, says John Heywood, a professor of mechanical engineering at MIT. "There's been enough development to say that it works. But with very different engine geometries, it's hard to work out just how good it is. Is it really better?" As research progresses, it will need to answer questions about efficiency, emissions, performance, and especially cost, Heywood says.Meanwhile, conventional internal combustion engines keep getting better, which could make it difficult for the free-piston design to get a foothold
fiber optic networking
With the increasing bandwidth requirements associated with broadband services, service providers and network operators are expanding and extending fiber optics further down line to accommodate present and future requirements. This network extension and expansion requires multiple fiber optic connectivity products in a myriad of forms. Trunk cables, distribution cables, high-density interconnect cables, and standard patch cords are just a few of the many types of products. Timbercon manufactures reliable fiber optic networking cables to support these networking applications.
Custom Stack Analysis
Custom Stack Analysis, LLC., was originally established in Alliance, Ohio, in 1965 by Mr. Ernest Kolm. In the year 2000, the company was acquired by Mr. James K. Gray, who has over 18 years experience in the field of air emissions testing. In the year 2005 Custom Stack Analysis, LLC. acquired the source testing assets of Envisage Environmental, Inc. Custom Stack Analysis, LLC. has capabilities for performing Stack Testing, Industrial Hygiene, Analytical Services, Burner Combustion Efficiency, Radon Testing and Indoor Air Quality. The company has performed work not only for small companies, but also many fortune 500 companies. A professional staff can ensure that any of your environmental needs are met with quality and competitive pricing.
Custom Stack Analysis, LLC., has been providing air emissions testing for the past 38 years. In this time, they have performed testing for many prominent clients, such as Stericycle, Inc., Goodyear Tire & Rubber Co., and WCI Steel, along with many other prominent companies. The company has extensive knowledge in testing for medical waste incinerators, printing operations, steel foundries, asphalt facilities, power plants, petroleum refineries, chemical plants, brick manufacturers, lumber processing, hazardous waste incinerators, rubber manufacturing, roofing production, plastic manufacturers, and many other types of operations. The company has also been providing its services to engineering companies, government agencies, and control system designers. The company has experience providing services internationally including Canada, Puerto Rico, Jamaica, Dominican Republic, Caribbean Islands and South America. If you have an international project that requires our services be sure to give us a call. In 2009 Custom Stack Analysis, LLC. joined a service alliance with Zaff International/Hi-Tech Ltd. for providing services in Saudi Arabia and the Gulf Coast countries.
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