Politecnico di Torino - Corso Duca degli Abruzzi, 24 - 10129 Torino, ITALY

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Stirling Cycle Machine

Combustable blendsFossil fuelsGreen EnergyStirling CycleThermodynamic Cycles


A volumetric thermal machine, operating according to the Stirling cycle, based on a rotary architecture with radially slidable vanes, in which the variation of the volumes of the working spaces is realized arbitrarily by means of a proper design of the stator chambers. The invention also relates to a method for operating such a machine.

Technical features

The proposed concept allows to improve the performance of the real cycle in terms of specific work and efficiency with respect to the traditional Stirling machines. In particular, this architecture does not impose any mechanical or kinematic constraint on the choice of the law of variation of volumes, making it possible to accurately reproduce the law prescribed by the ideal Stirling cycle and, more in general, to optimize it on the basis of the real machine behavior. Moreover, the proposed configuration allows the simultaneous evolution of multiple thermodynamic cycles inside the machine, contributing to increase the compactness of the device. In this way, the regeneration phase can be performed with a direct heat exchange between two cycles that simultaneously perform the isochoric cooling and isochoric heating phases. Furthermore, different technical solutions are introduced to increase the efficiency of the heat exchange during the compression and expansion phases. Finally, the machine can operate with a two-phase working fluid with dispersed liquid phase, in order to exploit the phase transition to increase the work of the cycle.

Possible Applications

  • Conventional fossil fuel energy conversion;
  • Renewable energy conversion (Biomass or Solar);
  • Waste heat recovery (exhaust gas or cooling fluid of internal combustion engines, hot gases in industrial processes);
  • Operating machine;
  • Heat pump and/or refrigeration.


  • More compact, higher specific power and better efficiency with respect to the state-of-the-art Stirling machines;
  • Possibility to operate with a two-phase working fluid allows to exploit low temperature heat sources, making it suitable for waste heat recovery applications.