The field of the present invention is turbomachinery and particularly double fluid processes and systems. Conventionally, power recovery from a heat source has generally employed the heating of a working fluid, expansion of the resulting vapor through a turbine or other engine and condensation of the resulting expanded vapor for reheating. When high temperatures are available as the source of heat, particularly higher than 300.degree. F., high boiling liquids such as benzene and toluene must be considered because a working fluid does not efficiently absorb heat at temperatures above its critical temperature, the temperature at which the fluid can no longer exist as a liquid. However, the use of such fluids is generally not advantageous because the condensing pressure at reasonable temperature levels is so low that the resulting vapor volume is excessive. Thus, the turbine must be large and expensive to accommodate such fluids.
To overcome the foregoing difficulties, it has been known to employ two fluids, namely mercury and water for the recovery of power from burning fuels. Such a system employs two cycles run at different temperatures with heat exchange used to condense the higher boiling point liquid and heat the lower boiling point liquid. However, economics were not found to encourage the use of the water-mercury system above the temperature of boiling pressurized water. Other fluids exhibit particular difficulties as far as sealing and contamination of bearing lubricants. Consequently, difficulties exist for both the single fluid system and previously proposed double fluid systems.