Numerical investigation on steam jet submerged in subcooled water under different ambient pressures

This paper aims to investigate the effect of ambient pressure on the thermal hydraulic behavior of stable steam jet during the process of direct contact condensation (DCC). Three-dimensional steady CFD simulation was conducted. A thermal equilibrium phase change model was inserted as a user defined function (UDF) to simulate the process of steam jet condensed into subcooled water. The shape of steam plume and axial temperature distribution were compared between experimental and numerical results, and good agreements were obtained. The steam plume shapes under different ambient pressures were obtained. The transformation of flow pattern from annular flow to bubble flow along axial direction was observed from the cross-sectional slices at different axial locations. Then the axial parameters such as velocity, temperature and static pressure under different ambient pressures were investigated. The existence of expansion and compression wave was verified due to the existence of the fluctuation of axial temperature. Besides, the average heat transfer coefficient ranges from 0.97 to 1.08 MW/m² K when ambient pressure ranges from 80 to 200 kPa.