22-10-2014, 02:43 PM
Abstracts: The Stirling engine, an example of an external combustion engine, is an emerging prime mover technology for distributed generation (DG) applications. In a Stirling engine, heat is transferred through the hot-end cylinder walls to a confined working fluid and is then converted to mechanical work via the Stirling thermodynamic cycle. To complete the cycle, heat is absorbed from the working fluid through the cold-end cylinder walls by a coolant. This differs from an internal combustion (IC) engine, which relies on the ignition of fuel within the engine cylinder to force the piston down with large amounts of heat discarded in the exhaust gas. Kinematic Stirling engines have a crankshaft with a conventional generator, whereas free-piston Stirling engines typically generate electric power with a linear alternator. In general, Stirling engines have comparitively high thermodynamic efficiencies. Because they need only heat, Stirling engines also permit high fuel-flexibility and allow for better control of emissions. However, in spite of these benefits, the IC engine has still become the incumbent prime-mover technology for transportation and stationary power generation applications, while the Stirling engine has yet to reach commercialization. This is likely owing to size and weight benefits of the IC engine combined with a number of other design and operational advantages.