enters the second heat exchanger 7 through the fifth valve v 5 along with the operation of the water nozzle mechanism 6 the gaseous actuating medium is cooled down and liquefied to the liquid actuating medium by evaporating the wet second fluid and then returns to the first pressure vessel 3 again through the fifth valve v 5 so that the pressure in the first pressure vessel 3 drops to ensure there is a pressure difference between the second pressure vessel 4 and the first pressure vessel 3 thus the liquid actuating medium in the second pressure vessel 4 continuously flows into the hydraulic power generator 2 till the control device 8 detects the liquid level in the second pressure vessel 4 is below the predetermined threshold using the corresponding one of the two liquid level sensors 5 in the second pressure vessel 4 at this moment the control device 8 switches the open close state of the first valve v 1 to the tenth valve v 10 so far the system runs normally every time the liquid level in the first pressure vessel 3 or the second pressure vessel 4 is below the predetermined threshold the control device 8 will immediately switch all of the valves and then the system starts a new turn for generating power in this embodiment the actuating medium with a low boiling point may be the cooling medium r22 chlorodifuoromethane by looking up the saturation temperature pressure chart that is known for the cooling medium r22 it is appreciated that.