高速蒸汽与过冷水直接接触凝结局部换热特性研究

Aiming at the direct contact condensation process of steam jet with subcooled water, a visualized experimental rig composed of rectangular steam nozzle and mixing chamber was designed and built. The flow field was observed when the steam mass flux, water mass flux and water temperature were in the range of 200 - 600 kg·m^-2·s^-1, 4 - 18 t·m^-2·s^-1 and 20 - 50 ℃, respectively. The steam-water interfacial fluctuation was investigated by image processing techniques, and a model for calculating local heat transfer coefficients was established. Besides, the relationship between interfacial fluctuation and local heat transfer characteristic was also studied. The results indicate that the interfacial wave observed in the research implies an interfacial instability, the interfacial wave amplitude and local heat transfer coefficient increase along the interface, and a relatively great local heat transfer coefficient can be achieved at steam jet tail. Furthermore, the interfacial fluctuation can enhance the heat and mass transfer in the condensation process of steam jet in water flow.