Numerical simulation of hexane condensing flow in throttle

If there are foreign nuclei(solid particles or liquid droplets etc.) existing in natural gas flow, condensation of hexane would take place on the foreign nuclei, and thus both homogeneous and heterogeneous condensation would occur in the throttling process. A uniform mathematical model for homogeneous and heterogeneous condensing flow was built to study flow field characteristics and condensation properties of hexane in the throttle valve. The effects of initial particles radius, concentration of the nuclei, back pressure ratio and total temperature on condensation properties of hexane were analyzed. It was shown that differential pressure and velocity of natural gas were very high in the throttle valve, and condensation was completed in a very short time. Owing to the high free energy barrier, homogeneous condensation of hexane could not occur until very high supersaturation ratio was reached. Homogeneous condensation would be restrained if both condensations coexisted in the condensing flow, which would cause the decrease of homogeneous condensation mass fraction. And the suppression effect became obvious when initial radius and concentration of the nuclei increased, under this circumstance the proportion of homogeneous condensation reduced compared to the case that only homogeneous condensation occurred. As back pressure ratio and total temperature increased, supersaturation ratio reduced which would cause the decrease of total condensation mass and proportion of homogeneous condensation simultaneously.