Development of technologies on innovative-simplified nuclear power plant using high-efficiency steam injectors. (13) Study on heat transfer of direct condensation of steam on subcooled water jet

Steam condensation to a water jet in a steam injector was examined by measuring the radial and the axial distribution of temperature and the velocity in the injector. The measured velocity distribution exhibited that the velocity of steam around the water jet was almost equal to the sonic velocity and the velocity at the peripheral region was considerably faster than that in the central region. It suggested that the water jet was greatly accelerated by the steam flow around the jet. The radial and the axial temperature distributions expressed that the water temperature at the central region jumped up in a short distance. It implied that considerably effective-radial heat transport took place in the water jet. The heat transfer coefficient of stream condensation to the water jet surface was much smaller than that of the ideal steam condensation. The heat transfer coefficient showed slightly decreasing trend for water subcooling and the condensation heat flux was almost independent on the subcooling. (author)