Simulation Of Paraffin Melting Heat Transfer In Circle Tube Based On Lattice Boltzmann Method

Most crude oil produced in China is waxy crude oil.Wax formation is a common problem in the process of crude oil exploitation and transportation,which directly affects the safe and efficient production of oil fields.Hot washing wax removal is a common wax removal method in oil fields,and the process of hot washing wax removal mainly involves the melting of paraffin wax.Therefore,the study of wax removal is of great significance to ensure the safe production of crude oil and reduce energy consumption.In this paper,the method of combining experiment and numerical simulation is used to study the melting process of paraffin inside the tube,reveal the law of phase change heat transfer of paraffin,and study the influence of different parameters on the melting process of paraffin.The main work and conclusions are as follows:(1)The physical and mathematical models of paraffin melting phase change heat transfer in circular tubes were established,and the mathematical model of paraffin melting heat transfer was solved by using lattice Boltzmann method based on double distribution function model.The density distribution function is used to describe the velocity field in the melting process of paraffin,and the temperature distribution function is used to describe the temperature field of paraffin.(2)The corresponding double-distributed lattice Boltzmann(DDF-LB)model was established to consider darcy flow effect caused by waxy structure,and the fuzzy region of paraffin transformation was regarded as porous medium.The accuracy of Boltzmann model was verified by visual experiments of paraffin melting process in circular tubes.(3)Based on the double-distributed lattice Boltzmann model,the problem of paraffin melting in circular tubes was solved,and the numerical study of paraffin melting in circular tubes under different Pr number,Ra number,Ste number,transformation radius and average transformation temperature was carried out.The behavior characteristics of paraffin melting process were analyzed by combining the numerical results.The results show that increasing Ra number can significantly accelerate the flow rate of natural convection of liquid paraffin and promote the melting process of paraffin.The increase of Pr number slows down the time of convective heat transfer,and the total melting time of paraffin wax is prolonged and presents a nonlinear change.Low Pr number is more conducive to the melting of paraffin wax in a short time.The change of Ste number only affects the rate of liquid phase ratio during phase transformation,but does not change the liquid phase ratio when phase transformation reaches quasi-steady state.The larger the phase transformation radius is,the slower the melting rate and the longer the melting time is.The higher average phase transition temperature significantly delayed the time of paraffin melting,which was not conducive to the melting of paraffin in the tube.