Research On The Vaporization And Expansion Behavior Of Cryogenic Liquid Leakage Pool

Cryogenic liquids such as liquefied natural gas,liquid nitrogen,and liquid oxygen are widely used in production and life as clean energy,refrigerants,combustion aids and other materials.However,cryogenic liquids also exist in storage and transportation due to their ultralow temperature and volatile characteristics.Big risk.Regarding the leakage and diffusion of cryogenic liquids,small and medium-sized experiments are carried out at home and abroad.Through theoretical analysis and numerical simulation,the large temperature difference heat transfer situation of cryogenic liquid vaporization on the solid surface is analyzed,and the boiling curve and related laws are proposed.This paper studies the vaporization characteristics and expansion behavior of cryogenic liquid after leakage,designs an experimental device for small-scale simulation experiments,and conducts experimental and theoretical analysis on the different conditions of cryogenic liquid on the concrete surface and water surface after the leakage of cryogenic liquid.The main research contents and conclusions are as follows:(1)For the two cases of non-expanded liquid pool and expanded liquid pool,two sets of visual experimental platforms were designed and built,including supplementary lighting system,high-speed image acquisition system,quality measurement system,temperature measurement system and data acquisition system.Among them,the non-expanded vaporization platform considers that liquid nitrogen absorbs heat and vaporizes from the limited concrete surface,and the surrounding is designed with an adiabatic cofferdam.In order to facilitate observation and shooting,windows are designed;the extended vaporization platform considers keeping the concrete base and the non-expanded vaporization platform the same,and the design is sufficient A large diffusion area is surrounded by toughened glass to form a visible cofferdam.Considering the safety of the laboratory,liquid nitrogen is selected as the medium for the experiment.(2)A simulation experiment on the leakage of liquid nitrogen on the concrete surface was carried out to study the vaporization characteristics and expansion behavior of cryogenic liquid on the solid surface.For the non-expanded liquid pool,combined with the characteristics of the bubbles in the cryogenic liquid pool at different boiling stages,the empirical correlation coefficients of the boiling mode are corrected according to the experimental values,and the prediction model is obtained by coupling the heat transfer theory,and the two empirical formulas of film boiling are compared.Through error analysis,it is concluded that the empirical formula of Klimenko and Kutableladze and the heat conduction model are coupled to predict the vaporization rate and vaporization quality error is smaller;for the expanded liquid pool,based on the study of the non-expanded liquid pool,the expansion of the cryogenic liquid pool on the concrete surface is studied The vaporization behavior of the expanded liquid pool is predicted,and the results are consistent with the experimental values.The coupling model obtained in the non-expanded case is extended to the expanded case,and the vaporization rate of the expanded liquid pool is predicted.The predicted results are basically in agreement with the experimental values.(3)A simulation experiment of liquid nitrogen leakage on the water surface was carried out to study the vaporization characteristics and expansion behavior of cryogenic liquid on the water surface.The high-speed camera was used to capture the characteristics of vaporized steam on the water surface,the survival of the underwater cryogenic liquid column during the first,middle and late stages of the experiment,and the icing situation on the water surface after the experiment.The experimental data showed that as the experiment progressed,the underwater cryogenic liquid The survival distance of the column gradually shortens,and the cryogenic liquid pool gradually expands on the water surface and multiple boiling points appear underwater;through the heat transfer and force analysis of the cryogenic liquid pool expansion,combined with the experimental data,the diffusion constant is corrected to 0.371,and the experimental radius is predicted The analysis of the vaporization behavior of cryogenic liquid leaking on the water surface shows that the vaporization process of the cryogenic liquid pool on the water surface mainly presents film boiling and transition boiling.