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Abstract
The condensation from the gaseous supersatured state plays an important role in numerous problems of interest in science and technology, such as the formation of aerosols or condensing matter in astrophysical application, expansion flows in steam turbines, humid air flows around aircraft wings, expansion flows in expansion turbines during natural gas transportation, cloud physics, refrigeration technology or in phase separation devices and other areas The present investigation comprises theoretical and experimental studies for the condensation of natural gas by homogeneous nucleation of liquid DROPlets during expansion through a supersonic nozzle The theoretical treatment for the condensation problems of natural gas in supersaturated conditions was based on the modified nucleation theory. A kinetic theory approach for determining the rate of DROPlet growth has been developed. On the other hand, the nonequilibrium characteristics during the spontaneous condensation (i.e. homogeneous condensation) within supersaturated natural gas are studied In this study, three condensation models are presented. These models refer to a specific combination of continuity, momentum, energy, nucleation, DROPlet growth, surface tension and gas dynamic equations Modified equations for the classical nucleation rate, DROPlets surface tension and the thermodynamic properties of the condensing vapour are used in the present theoretical models. One characteristic aspect of nucleation and DROPlet growth in natural gas is that natural gas consists of many different components Real natural gas properties are considered to deduce the real medium effects on the nonequilibrium flow behaviour The factors influencing condensation in high speed expanding flows of natural gas are studied The effects of changing the condensation coefficient (α), the coefficient of nucleation work (β) and the initial pressure (po) on the flow and condensation characteristics during the expansion of natural gas through a