Numerical Simulation And Experimental Study On The Heat Transfer Enhancement And Fouling Control By Spiral Fluidized

Heat exchange equipment is the highly working unit in chemical industry,Tube fouling has great influence on the performance of heat-transfer.Based on the research of integrated spiral flow field and fluidized heat transfer enhancement,spiral inserted and liquid-solid two-phase composite heat transfer enhancing technology is proposed.Under the guidance of the liquid-solid two-phase flow theory and discrete element method,a numerical simulation of the flow field/heat transfer conditions and the concentration distribution/wear rate of solid particles with spiral inserted and liquid-solid two-phase flow tube has been made.Physical models are combined by four factors three levels using orthogonal analysis.The spirals are simulated with pitch 20/40/60mm,outside diameter 20/24/30mm and wire diameterl/1.5/2mm.The concentration of solid particles is divided into three kinds about 2%,4%,6%and 2%respectively.In-depth analysis of heat transfer performance and scale removal and prevention is made,also with the optimization of structure parameters and particles concentration.Wire diameter is the most important parameter related to the scale removal and prevention ability,but also the explanation from the particle concentration distribution and the number of particles colliding with the wall is required.Then coupled the discrete element particles simulation theory and fluid dynamics,specifically coupling the manifestation of EDEM-Fluent,the motion parameters on particle level got.With the orthogonal analysis of the front simulation results of heat transfer performance and scale removal and prevention,gets the feasible method of optimized spiral fluidized heat transfer performance.Algorithms of global optimization fitting out of the spiral flow remove anti-scale ability and the quantitative relationship with particle motion parameter.Also has carried on the preliminary validation model.By building experimental platform of spiral heat exchanger fluidization independently.Experimental study on the structural parameters of spiral has been made,particles volume concentration and particle size's influence on the heat exchange performance and its act on the scale removal and prevention has been qualitatively researched.The results shows that:1)fluidized particles effect heat-exchange performance significantly and the heat transfer coefficient of spiral fluidization increased by 40%?50%than spiral flow,and the spiral fluidized heat exchange performance increases with the increase of wire diameter and outside diameter;2)compared 3 mm with 5 mm fluidized particles for heat transfer performance,under the velocity of lm/s the heat transfer coefficient of bigger particles is 5%?10%higher;3)the heat transfer coefficient of higher fluidized particles concentration(particle conveyor motor 110 RPM)is increased by 30%than which of small concentration(70 RPM).On the other side,changing the parameters to obtain experimental data then make comparison of experimental data.By testing the heat transfer coefficient for the influence of various parameters on the scale removal and prevention ability,the wear ability fitting formula been verified.