Abstract: Device converting thermal energy into kinetic energy, related to the group of machines based on four-phase basic thermodynamic cycles. It uses rarefied gas in a novel three-phase cycle, of which the first phase is a spontaneous isothermal gas aggregation (0 - - - 1), equivalent to an ideal isothermal compression, followed by an adiabatic expansion (1 - - - 2), with work produced at the expense of the internal thermal energy of the gas via a gas turbine (5), and by an isobaric expansion (2 - - - 0)), where the expanded gas is reheated via a heat exchanger (6), while cooling the ambient air (7).