Research On Resistance Characteristics Of The Automatic Evaporation Flow Of Liquefied Natural Gas And Pipeline Stress

In LNG(liquefied natural gas)fuelling station,the liquefied natural gas which comes from the storage tank,flowing through a pipe,fluids to the inlet of immersed pump only for low temperature liquid by self-priming function.The flow resistance and self-driven evaporation phenomenon in the flow region as well as the stress distribution in the pipe impact the operation of the LNG fuelling station greatly.For the automatic evaporation of LNG caused by the decreasing pressure and increasing temperature exists in the pipe,this paper studies the evaporation flow and acquired the relationship between the flow loss and the gasification intensity through a mathematic model of LNG evaporation.The results show that: the new mathematic model simulates the flow of LNG with automatic evaporation and reveals the characteristics of gas-liquid flow as well as the relationship between the flow loss and the gasification intensity that a moderate amount of gasification promotes the flow of LNG and severe gasification hinders the flow of LNG.Approximately replace the properties of liquefied natural gas and the natural gas with the properties of liquefied methane and gaseous methane which are recorded in ALLProps database.Programming properties of methane under pressure which varies from 0.1MPa to 1MPa and temperature which varies from 95 K to 150 K.Set up a mathematic model of evaporation for liquid and make the saturation temperature vary with pressure.The evaporation flow is simulated.Analyze the flow features of two-phase flow of gas-liquid.Get the result of pressure distribution,gas distribution and turbulent energy distribution and study the factors which impact the evaporation.In the respect of local flow loss,the flow losses of elbow and the stop valve are studied by numerical simulation method from the points of liquid temperature,volume fraction of gas in the liquid and the roughness of the wall.Build the flow region and the model of the elbow and stop valve respectively and through the VOF model,analyze the motion of the gas by capturing the location of bubbles.Come up with a method for analyzing the pipe stress distribution and pipe deformation based on the flow result.Discretization of the temperature field was loaded as the boundary conditions for pipe stress analysis,avoiding loading continuous boundary condition,by making the fluid coupling with the pipe wall.Pipe stress distribution and pipe deformation are acquired.Furthermore,the stress maximum cross section and the maximum deformation location are found and the change rule of stress on stress maximum cross section is acquired.