Retrograde Condensation as a Future Technology Base

The goal of the paper is to present an analytical description of the retrograde condensation (RC) phenomenon in the pure substances and the perspective of its utilization in the sustainable energy systems. Modern power storage and extraction technologies are based on equilibrium thermodynamic processes, not on the physicochemical nature of the working substances subjected to those processes. Practice and ingenuity guide the complex of the thermophysical and transport properties per application. The development of the JP7 fuel for a special aircraft in the US presents a perfect example [1]. Sustainable energy requires an environment-based approach such as targeting fluids as operational environments with certain optimal points or loci coveting to specific ways of power extraction or transmission. Usage of such intrinsic locations in the fluids would constitute a fundamentally new technology. Retrograde condensation presents such an opportunity. It manifests itself in a pure fluid as a reverse behavior of the vapor quality at a constant specific volume to the left of the critical value. For every specific volume there is only one unique point where the rate of the quality variation with temperature dx/dT changes its sign (from positive to negative). The formula for the locus connecting those points defines the retrograde condensation line. Around each point on this line a limit cycle of evaporation/condensation takes place with the frequency of oscillations depending solely on the properties of substance. These oscillations lead to the associated pressure waves with significant amplitudes depending on the location of the point on the locus. The phenomenon can lead to several energy-related applications with a strikingly different design approach-the adjustment of the device to the substance, its specifics. Here both primary power-generating parameters (pressure amplitude and oscillation frequency) become substance-dependent commensurate to the new requirements of sustainable energy-related designs.