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:''This article is about the "adiabatic" Stirling cycle. For the "idealized" Stirling cycle , see the Stirling engine article.'' The Stirling cycle is a thermodynamic cycle that describes the general class of Stirling devices. This includes the original Stirling engine that was invented, developed and patented in 1816 by Reverend Dr. Robert Stirling with help from his brother, an engineer. The ideal Otto and Diesel cycles are not totally reversible because they involve heat transfer through a finite temperature difference during the irreversible isothermal heat-addition and heat-rejection processes. The irreversibility renders the thermal efficiency of these cycles less than that of a Carnot engine operating within the same limits of temperature. Another cycle that features isothermal heat-addition and heat-rejection processes is the Stirling cycle. The Stirling cycle is an altered version of the Carnot cycle in which the two isentropic processes featured in the Carnot cycle are replaced by two constant-volume regeneration processes. The cycle is reversible, meaning that if supplied with mechanical power, it can function as a heat pump for heating or cooling, and even for cryogenic cooling. The cycle is defined as a closed regenerative cycle with a gaseous working fluid. "Closed cycle" means the working fluid is permanently contained within the thermodynamic system. This also categorizes the engine device as an external heat engine. "Regenerative" refers to the use of an internal heat exchanger called a regenerator which increases the device's thermal efficiency. The cycle is the same as most other heat cycles in that there are four main processes: compression, heat addition, expansion, and heat removal. However, these processes are not discrete, but rather the transitions overlap. The Stirling cycle is a highly advanced subject that has defied analysis by many experts for over 190 years. Highly advanced thermodynamics is required to describe the cycle. Professor Israel Urieli writes: "...the various 'ideal' cycles (such as the Schmidt cycle) are neither physically realizable nor representative of the Stirling cycle".〔Organ, "The Regenerator and the Stirling Engine", p.xxii, Forward by Urieli〕 The analytical problem of the regenerator (the central heat exchanger in the Stirling cycle) is judged by Jakob to rank "among the most difficult and involved that are encountered in engineering".〔Organ, "The Regenerator and the Stirling Engine", p.7〕〔Jakob, M. (1957) ''Heat Transfer II'' John Wiley, New York, USA and Chapman and Hall, London, UK〕 ==Idealized Stirling cycle thermodynamics== The idealized Stirling cycle consists of four thermodynamic processes acting on the working fluid (See diagram to right): # Isothermal expansion. The expansion space is heated externally, and the gas undergoes near-isothermal expansion. # Constant-volume (known as isovolumetric or isochoric) heat removal. The gas is passed through the regenerator, thus cooling the gas, and transferring heat to the regenerator for use in the next cycle. # Isothermal compression. The compression space is intercooled, so the gas undergoes near-isothermal compression. # Constant-volume heat addition. The compressed air flows back through the regenerator and picks up heat on the way to the heated expansion space. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Stirling cycle」の詳細全文を読む スポンサード リンク
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