Numerical investigation on the interfacial characteristics of steam jet condensation in subcooled water flow in a restricted channel

摘要

As a kind of direct contact condensation, steam jet condensation in subcooled water flow is very common in various industrial applications. Particle model has been employed to investigate the interfacial characteristics of the steam jet condensation in subcooled water flow in a restricted channel, in which a thermal phase change model was inserted into ANSYS CFX as CFX Expression Language (CEL) to simulate the interphase heat and mass transfer process. To validate the model correctness, the steam plume and temperature profiles were compared with the experimental data. The interfacial characteristics including the variation of steam-water interface, local heat transfer coefficient and local condensation rate have been discussed under different operating conditions. Based on the dynamic equilibrium of steam supply and its condensation by the ambient water flow, the steam plume variation was analyzed. The axial profiles of thermodynamic parameters along the nozzle axis were studied with the theory of expansion and compression waves to reveal the formulation mechanism of ellipsoidal steam plume. Then the supersonic flow was observed at some distances from the straight nozzle exit in the numerical results as the related experimental results indicated. The numerical results show that steam plume expands with steam mass flux and water temperature increasing, while it contracts with the increase of water Reynolds number. With the increase of water inlet temperature, the local condensation rate decreases. As the Reynolds number of water flow increases, the local heat transfer coefficient increases and the local condensation rate increases as well. (C) 2019 Elsevier Ltd. All rights reserved.