The Variable Phase Cycle

is a patented power system that generates power from waste heat and geothermal resources.


The Variable Phase Turbine enables an efficient system for waste heat recovery and geothermal power generation. Heat is transferred to a pressurized liquid in a liquid-liquid heat exchanger eliminating a boiler, which has a pinch point limitation. The liquid is flashed in a near isentropic two-phase nozzle, driving a Variable Phase Turbine. The cycle is closed by condensing the vapor and subsequently pressurizing the liquid to return it to the heat exchanger. The result is an increase in net power from a waste heat source or geothermal resource by 20-40% relative to the traditional Organic Rankine cycle.


The test system shown above was designed and built with support from Siemens AG. It is the first closed cycle two-phase system to produce power from the Variable Phase Turbine.


Please refer to our technical paper about the Variable Phase Turbine and its application to geothermal power production in a Variable Phase cycle for a more detailed description of the technology.



Above: A working test set-up of the Variable Phase cycle at Energent Facilities.

Below: A model of a 1 MW Variable Phase cycle geothermal power plant.

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