| Increasing exploitation and consumption,crude oil is becoming heavier and poorer in quality.Deep vacuum distillation,as an effective manner on heavy oil processing,could fairly well remedy the adverse impact from heavier oil.This is the research background of this paper.This paper put eyes on pressure-swirl nozzle and its spray heat transfer process,with the aid of the theories and methods of computational fluid dynamics and computational heat and mass transfer.Strategy of comparison between numerical simulation and experiment reported in the literature is applied.Equivalent 2D grid is employed to simulate axisymmetric 3D flow.Multiphase model VOF,turbulence model RSM linear Pressure-Strain and phase change model Lee are respectively adopted.The nozzle flow characteristics of internal and external flow field with and without heat transfer are studied and analyzed.The significance of this research is to predict the distribution of flow field and grasp the coupling laws of fluid distribution,heat and mass transfer.Research results would like to provide supports for the design and optimization of large industrial equipment of direct contact condensation.Numerical simulation results indicate,(1)without heat transfer,increase on spray cone is smaller and break up length of liquid film shorter with the increase of nozzle flow rate.Inside the nozzle,pressure on upper part is high on the edge and low in the middle,distribution of tangential velocity is completely the opposite.Outside the nozzle,liquid film's tangential velocity,axial velocity and thickness decrease,radial velocity increases with axial distance from orifice increases.A new method for predicting film thickness on orifice is developed.(2)with heat transfer,the super-cooling degree of inlet liquid is found of influence on spray heat transfer process.When other conditions are same,compared with no heat transfer,breakup length is bigger,and gas flow field underwent great changes.Liquid flow field distribution is of the same. |
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