Numerical Simulation Of CaCO₃ Fouling Characteristics In Tube With Delta Wing Vortex Generator

The heat exchanger with fouling will directly affect the conversion rate and utilization rate of energy,so the existence of fouling has serious harm,while the vortex generator,which is the heat exchanger element of reactive power enhancement,can enhance heat transfer by inducing the vortex motion of the fluid.Because of its simple structure,it has been widely studied and applied.In order to study the comprehensive characteristics of the vortex generator,this paper simulated the heat transfer characteristics,flow resistance characteristics and the CaCO₃ fouling characteristics with delta wing vortex generator in pipe using CFD software and investigated the influence of arrangement spacing,angle of attack,wing length and included angle with vortex generator.The reliability of the fouling model was verified by the experimental results of smooth tube by referencing to relevant literatures.The results show that there are two symmetrical opposing vortices on both sides of the wing of the vortex generator and the fouling resistance of the enhanced tube is less than that of the smooth tube,which explains that the disturbance of vortex generator on the wall boundary layer can effectively control the deposition of fouling.The asymptotic fouling resistance increases with the increase of the arrangement spacing,the growth rate slows down gradually;the asymptotic fouling resistance increases first with the attack angle,which reaches the maximum at 90 degrees,and then decreases with the increase of the attack angle;the asymptotic fouling resistance decreases with the increase of wing length,which reduction rate increases gradually;the asymptotic fouling resistance decreases with the increase of the included angle,the reduction rate slows down gradually.At the same time,the influence of operating conditions on fouling characteristics with delta wing vortex generator in pipe was studied.It investigated the influence of concentration of working fluid,inlet velocity,wall temperature,inlet temperature on the fouling deposition rate,erosion rate and fouling resistance under the determined structure of the delta wing vortex generator.The results show that the working concentration and inlet velocity significantly affect the fouling characteristics.The deposition rate,erosion rate and fouling resistance increases with the increase of working concentration and wall temperature;deposition rate,erosion rate gradually increases with the increase of inlet velocity,and fouling resistance gradually decreases;the deposition rate increases slightly with the increase of the inlet temperature,The erosion rate and fouling resistance doesn't change obviously with the increase of inlet temperature which shows that the inlet temperature has little effect on the fouling deposition characteristics.