Research On Steam Condensation With Non-condensable Gases Under The High Pressure

With a high level of great safety and reliability,the integrated reactor is going to be one of the best option for small and medium sized reactors in lots of countries.In order to simplify the structure and design and enhance safety,the steam-gas pressurizer is usually utilized in the integrated reactor.The non-condensable gas is used to keep the pressure stable in the steam-gas pressurizer and the processes of heat and mass transfer during steam condensation in presence of non-condensable gas play an important role in the thermal-hydroulic characteristics in the pressurizer.Therefore,the characteristic of heat and mass transfer during steam condensation with non-condensable gas need to be paid more attention and as so far the researches on these subjects are focusing on the low pressure,there are rarely researches on the high pressure.Hence,the effects of non-condensable gases on the characteristics of heat and mass transfer during steam condensation under high pressure are necessary and significant.In this paper,experimental and theoretical researches on the characteristics of heat and mass transfer during steam condensation in the steam-gas pressurizer of the integrated reactor are presented.The steam condensation experimental system under high pressure and natural convection was built and experimental researches on the effects of non-condensable gases on the process of heat and mass transfer during steam condensation have been performed and the distribution of non-condensable gases in the steam/gas mixture in the pressurizer has also been investigated.Based on the experimental data,a steam condensation heat and mass analogy model was built and improved to investigate the characteristics of heat and mass transfer during steam condensation.The experiments consisted of two parts: Engineering experiments of heat and mass transfer during steam condensation—experimental researches on condensation heat transfer in the steam-gas pressurizer;Mechanism experiments of heat and mass transfer during steam condensation—experimental researches on condensation transfer under high pressure and natural convection in large space.Based on the integrated natural circulation test loop,engineering researches on the characteristics of heat and mass transfer during condensation in the steam-gas pressurizer have been conducted.Nitrogen was chosen and its mass fraction was about 5.53%,the effects of pressure and heating power in the reactor on the steam condensation were investigated respective.In the mechanism experiments,the processes of heat and mass transfer during steam condensation on the vertical wall with non-condensable gases were researched and the factors,for instance,pressure,the variety and mass fraction of the non-condensable gas,subcooling of wall and the distribution of gas in the steam/gas mixture,have been taken into account.The characteristics curve of steam condensation with non-condensable gases under high pressure were obtained in the experiments.As for the theoretical model,a heat and mass analogy model was accomplished and improved in this paper,changing the situation which the previous models have a bad accuracy for the heat transfer during steam condensation under high pressure.Taking the compression effects of high pressure on the steam and non-condensable gas into account,a gas compression factor was introduced and the steam and non-condensable gas were treated as real gas,suction factor and improved diffusion coefficient were also introduced.Compared with the experimental data,the model in this paper has great agreement and accuracy,the characteristics of heat and mass transfer during steam condensation under high pressure can be described with the heat and mass analogy model in this paper.