boiling with liquid at low pressures subsequent to the engine jacket the two phase fluid is passed through an exhaust heat recovery boiler and then to the vapor separator where the vapor and liquid phases are separated the saturated vapor is then piped to the heat load and the saturated liquid is circulated to the engine via the separately driven electric centrifugal pump aided by a variable area jet inducer eductor for variable load and speed applications the feed pump and eductor are automated as an energy conservation measure the pump speed is modulated to schedule its output as a function of the fluid vapor fraction entering the vapor separator this is accomplished by a state of the art signal following induction motor control that modulates the pump speed to maintain a given ratio of recirculated flow to feed flow as measured by appropriately placed flow meters and calculated by the microprocessor the eductor primary nozzle area is modulated by a state of the art position control which maintains a given primary flow to total flow ratio as the pump output varies so that adequate flow rate through the engine maintains nucleate boiling the proof of concept of the invention consisted of an experimental evaluation of the effects of the.