Limits to Energy Conversion

Arjan van der Schaft; Dimitri Jeltsema

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arXiv · 2006.15953

Limits to Energy Conversion

Arjan van der Schaft·Dimitri Jeltsema

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Abstract

A consequence of the Second Law of thermodynamics is that no thermodynamic system with a single heat source at constant temperature can convert heat into mechanical work in a recurrent manner. First we note that this is equivalent to cyclo-passivity at the mechanical port of the thermodynamic system, while the temperature at the thermal port of the system is kept constant. This leads to the general system-theoretic question which systems with two power ports have similar behavior: when is a system cyclo-passive at one of its ports, while the output variable at the other port (such as the temperature in the thermodynamic case) is kept constant? This property is called `one-port cyclo-passivity', and entails, whenever it holds, a fundamental limitation to energy transfer from one port (where the output is kept constant) to the other port. Sufficient conditions for one-port cyclo-passivity are derived for systems formulated in general port-Hamiltonian form. This is illustrated by a variety of examples from different {(multi-)}physical domains; from coupled inductors and capacitor microphones to synchronous machines.

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Arjan van der Schaft, Dimitri Jeltsema. 2020-06-29. Limits to Energy Conversion. https://arxiv.org/abs/2006.15953

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