Heat engine

Abstract

There is disclosed a heat engine 10 comprising: a heat exchanger 12 to transfer heat from a heat source 100 to a working fluid; a positive displacement expander 16 configured to receive inlet working fluid from the heat exchanger 12 and discharge expanded working fluid as a multiphase fluid so that there is an overall volumetric expansion ratio between the expanded working fluid and the inlet working fluid which is a function of an inlet dryness of the inlet working fluid; a variable expansion valve 14 disposed between the heat exchanger 12 and the expander 16, the valve being configured to introduce a variable pressure drop in the working fluid to vary the inlet dryness; and a controller 30 configured to maintain the overall volumetric expansion ratio by controlling the valve 14 to compensate for variable heat transfer to or from the working fluid.

Dependencies are inferred from the claim text.