Abstract: A dual stage compressor for use with condensable fluids comprising a condensable fluid expansion stage in fluid and thermal communication with a condensable fluid compression stage wherein the condensable fluid expansion stage comprises a compressor head/heat exchange including a fluid expansion nozzle disposed in operative relationship relative to an condensable fluid expansion chamber formed therein and the condensable fluid compression stage comprises a reciprocating compression piston movable between a first and second position disposed within a compression cylinder having an intake port and an intake valve movable between a first and second position to selectively control fluid flow from the condensable fluid expansion chamber to the interior of the compression cylinder and an exhaust port and an exhaust valve movable between the first and second position to selectively control fluid flow from the compression cylinder such that when the reciprocating compression piston moves from the first to second posi