Numerical study on the differences in condensation characteristics in throttle valves with different structures

Abstract

There are differences in spontaneous condensation characteristics in throttle valves with different throat types that remain unknown. Moreover, the effects of the structural parameters on condensation characteristics have not been studied yet. Hence, this paper numerically compares the condensation characteristics of the CH4-C2H6 mixture in throttle valves with an orifice plate throat (OTV) and venturi throat (VTV) to reveal the differences. Moreover, this paper discusses the effects of the outlet section diameter of OTV and the throat angle of VTV on condensation characteristics in detail. The results show that the maximum pressure and temperature drops in VTV are slightly lower than in OTV, but the positions corresponding to the minimum pressure and temperature are closer to the throat than in OTV. Hence, the nucleation and droplet growth regions in VTV are 0.0034 m ahead of those in OTV. The maximum liquid mass fraction in OTV is 11.01 % higher than in VTV. As a result, the ethane condensation rate in OTV is 10.62 % higher than in VTV. In OTV, a larger outlet section diameter can promote condensation, in detail, the ethane condensation rate is 9.5 % and 15.4 % under the outlet section diameter of 19 mm and 27 mm. In VTV, the liquid mass fraction increases with increasing throat angle. The ethane condensation rate is higher under a larger throat angle, in detail, the ethane condensation rate is 7.1 %, 7.9 %, and 8.6 % under throat angles of 40°, 60°, and 80°, respectively.