Abstract
The thermodynamic analysis of the coupling of one cycle in the operation of a reversible heat engine with a work-degrading step in which the whole of the engine’s work output is frictionally degraded into heat at the temperature of its cold reservoir, allows identification of the fact that the engine’s reversibility is dependent on the continued availability of its work output. As long as this work remains available the engine will be reversible, this on reason of the fact that the initial condition can be restored via the simple expedient of using the said work to propel the inverse cycle. The moment this work becomes, for whatever reason, unavailable, restoration of the engine’s initial condition becomes impossible, and what was a reversible engine becomes irreversible. The inability of current thermodynamic terminology to deal with this situation is brought to light and a simple suggestion aimed at correcting this deficiency is advanced.
Highlights
The thermodynamic analysis of the coupling of one cycle in the operation of a reversible heat engine with a workdegrading step in which the whole of the engine’s work output is frictionally degraded into heat at the temperature of its cold reservoir, allows identification of the fact that the engine’s reversibility is dependent on the continued availability of its work output
As long as this work remains available the engine will be reversible, this on reason of the fact that the initial condition can be restored via the simple expedient of using the said work to propel the inverse cycle
The inability of current thermodynamic terminology to deal with this situation is brought to light and a simple suggestion aimed at correcting this deficiency is advanced
Summary
As noted in Planck’s previous quote, it is the ‘restoration everywhere of the exact initial state’ what constitutes the requirement to be fulfilled if a process is to be called reversible In other words, it is only on reason of the fact that all of the bodies involved in the process of interest can be returned to the precise condition each of them had before any change had taken place that the process can be called reversible. Confirmation of the former is required before the latter qualifier can be attached to any given process
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