Technology & Research
Microsteam Turbine
Euler Turbine
Variable Phase Turbine
Variable Phase Cycle

Variable Phase Cycle

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 sensible 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.