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| Re: Who do YOU Endorse for the Presidency? (318268) | |||
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Re: Who do YOU Endorse for the Presidency? |
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Posted by SelkirkTMO on Wed May 14 21:02:56 2008, in response to Re: Who do YOU Endorse for the Presidency?, posted by JournalSquare-K-Car on Wed May 14 20:44:05 2008. On the "charge a storage device" angle, NOW you're onto something. The problem with Stirling engines is the warmup time. It's considerable, much like the old Stanley Steamers or a Steam Locomotive ... you have to heat it up before you can go. They considered a hybrid design for a car where batteries would run the electric motor until the Stirling was heated up and ready to go.For STATIONARY purposes, there's been much more success, particularly in solar furnace generation. And yes, there are Stirling heat pumps in use. I've been following this for quite a number of years, hoping to see MTI bring something practical to market. Alas, they haven't as yet. :( From the automotive standpoint, you might find this historical interesting: ------------------------------------------------------ STIRLING AUTOMOTIVE ENGINE PROGRAM Program Description and History The transportation sector is the dominant user of oil in the United States, accounting for more than 60 percent of the nation’s oil demand and using more than is domestically produced. Passenger cars are the most energy-intensive subsector of the transportation sector, consuming over one-third of all transportation energy; they consumed 8743 trillion Btu out of the total 24,411 trillion Btu consumed in the transportation sector in 1997. These data are taken from the 1999 Transportation Energy Data Book, which is published annually by the Oak Ridge National Laboratory and DOE (Davis, 1999). DOE’s Office of Transportation Technologies (OTT) worked for many years to develop Stirling engines for automotive applications. The rationale for this work included the potential for high average thermal efficiency, multifuel capability, low maintenance requirements, smooth operation, and low emissions. None of the efforts to date has resulted in the development of a commercial product in the intended use or other uses. The first DOE Automotive Stirling Engine program was initiated in response to the energy crisis of the mid-1970s. The OPEC action spurred the examination of a wide range of alternative propulsion systems for autos. At that time, it was felt that the Stirling engine was attractive for an automotive engine because it offered high efficiency and multifuel capability, the latter point being particularly attractive because of the gasoline shortages and price volatility of the time. The Stirling engine was actually invented in 1816. In the late 1930s the Phillips Company in the Netherlands revived the engine and continued independent development for the next 20 years. In the late 1940s, General Motors started research on the engine and in 1958 signed a formal agreement with Phillips for cooperative R&D. By May 1969, GM had accumulated over 22,000 hours of operation on Stirling engines from 2 to 400 hp. Because the Stirling engine uses an external continuous combustion process, it can be designed to operate on virtually any fuel. Several automotive concepts were developed and evaluated along with the Stirling engine. The second foray into Stirling engine development came about as a result of the PNGV program. OTT worked with Mechanical Technology Incorporated (MTI) from 1978 until 1987 to develop an automotive Stirling engine. The goals of the program included a 30 percent fuel economy improvement, low emission levels, smooth operation, and successful integration and operation in a representative U.S. automobile. At the culmination of the program, the engine was demonstrated in a 1985 Chevrolet Celebrity, meeting all the program technical goals. The Stirling engine was never put into production for a number of reasons, including commensurate improvements in Otto cycle engines, high manufacturing cost, and lack of interest from the mainstream automobile manufacturers. Subsequent to DOE’s involvement, NASA supported further development of the MTI Stirling engine for a few years but then eventually abandoned it. From 1993 until 1998, General Motors teamed with Stirling Thermal Motors (STM) to develop and demonstrate a Stirling engine for hybrid vehicles as part of the PNGV initiative. The engine was designed to drive a generator in a series hybrid configuration. Six engines were eventually built by STM, and three were delivered to General Motors for testing. By the end of the program, the Stirling hybrid propulsion system was integrated into a 1995 Chevrolet Lumina. The Stirling hybrid vehicle failed to meet several key requirements. Specific shortcomings included lower-than-expected thermal efficiency, high heat rejection requirements, poor specific power, and excessive hydrogen leakage. The engine did meet its emission target, demonstrating half the ultralow-emission-vehicle (ULEV) standard. There are no plans for further development of the Stirling hybrid concept with GM or any other auto manufacturer. STM is working to commercialize a small Stirling-powered generator for commercial use. |
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