Two-phase fluid compressors – A review

Abstract. Two-phase fluid compressors in the scientific and patent literature are briefly reviewed. Early theoretical and empirical studies date back to the ‘80s, but currently no device is commercially available. This technology has a significant feature respect to the traditional circulation pumps and vapor compressors: in fact a two-phase fluid compressor is able to work with chemical species in the wet vapor phase (consisting of two phases liquid and vapor) in order to increase simultaneously their pressure employing the mechanical energy provided by a motor. Different types of two-phase fluid compressor have been conceived and analyzed. In the first part of this paper, principle of operation and main construction features are described for each class of two-phase compressors. In the second part, the applications of this technology in some related thermodynamic cycles are presented. In the third part advantages and critical aspects of two-phase compressors are analyzed. These devices can be employed in lieu of the traditional technology in order to pressurize a fluid in the wet vapor phase with less mechanical power, absence of complex pressure control systems, absence of a liquid-vapor separator and lower condenser size. Critical aspects of this technology are the two phases thermal equilibrium (related to the compressor performances), high mechanical pressures on the surfaces, lubricating oil washing, emulsions or foams, slugging and flashing liquid.