Investigation Of Direct Contact Condensation Of Saturated Steam On Sub Cooled Liquid And 2-dimensional Temperature Distribution

Passive safety has been a new concept that in order to raise security and reliability of nuclear power plant since twenty century eighty decades. When the nuclear reactor is in the state of leaking, the boric water's gravity characteristics can be used to supply water to core passively, which can cool the core urgently. While at the beginning of this process, because the steam condenses rapidly on the sub-cooled liquid, which makes the pressure of CMT (Core Makeup Tank) alter violently, the flow of supplying water diminishes and so affects the safety of nuclear reactor. At present, we know a little of saturated steam condensation with direct contact, therefore, it is necessary for study deeply. At different models and conditions, the author of this paper had experimental research and numerical simulation to the transient characteristics of saturated steam condensing on sub-cooled liquid with direct contact in CMT. The study results will benefit for the design of passive safety system in nuclear power plant and other industry equipments.While saturated steam condensing on sub-cooled liquid in CMT, the experiment studied the characteristics of condensation, response of pressure and distribution of temperature. The experimental parameters were as follow: the initial pressure of pressurizer P=0.2-0.6MPa and the initial water temperature of CMT T=20-80℃. There was three kinds of experiments have been finished: with sparger, without sparger, with porous spout.While different models and initial conditions, the difference in axial temperature and the temperature raise showed different characteristic. The author used 1-dimensional unsteady state heat conduction equation to calculate the thickness of hot water layer, (with sparger, without drain, with vapor space). All the experimental data fall in the ±23% predicted value.When used different models, such as small crevasse drain, with sparger and porous spout, the characteristics of pressure response will be affect largely. With drain and porous spout will increase the time of pressure balance, while with sparger will decrease the time of pressure balance. In visible experiment, the time of pressure balance decrease with the initial pressure of PRZ and temperature of CMT. The conclusion different from the results of prophase experiment and the conclusion which conducted by Gao Liang Liang. In drain experiments, the drain mass increased with PRZ initialpressure and initial temperature of CMT. After installed sparger, the drain mass increased much more than the mass without sparger. The results showed that installing sparger would benefit largely for the drain capability of CMT.Through comparing the Rt , the author classified the condensation model as follow: steam supply limited model, condensation limited model and pressure balance model. In different model experiments, the variety of condensation heat transfer coefficient before pressure balance as follow: when PRZ initial pressure equated, the coefficient decrease with CMT initial temperature, when CMT initial temperature equated, coefficient increased with PRZ initial pressure. On the experimental conditions without drain, with vapor space, the quantity of condensation heat transfer before pressure balance occupied total heat transfer was 75-84%. Through experimental data and theory of direct contact condensation, a correlation was studied out, and all the experimental data fall in the ±17%-23% predicted value.The author simulated the model through new concept, fond out that the situation and scale of sparger affected the pressure balance time of CMT. The calculated results agree with the experiment result well, and it is benefit for study of optimization sparger.