Study On Characteristics Of Magnesia Particulate Fouling Of Tetrahedral Vortex Generator In Rectangular Channel

Fouling is the solid or slime material that gradually builds up on the surface of the heat exchange equipment that interfaces with the fluid,which is an important cause of degradation of heat transfer performance.As a product of passive heat transfer enhancement technology,vortex generator can not only enhance heat transfer but also inhibit the accumulation of fouling on the heat exchange surface by inducing vortex to increase the fluid disturbance and by thinning the boundary layer of the heat transfer surface.In this paper,characteristics of Mg O particulate fouling of the tetrahedral vortex generator were experimentally studied.First of all,the influence mechanism of tetrahedral vortex generators on MgO particulate fouling were investigated by the experiments of the rectangular channels with or without tetrahedral vortex generators.The results show that the down-wash vortex pairs is induced when the working fluid flows through the tetrahedral vortex generator,and the vortex pairs have an important effect on the adhesion and erosion of the fouling.The rectangular channels installed with the tetrahedral vortex generator have less deposition of fouling.Secondly,the effects of the height,length and width of the tetrahedral generators on characteristics of particulate fouling were investigated based on the experimental design of orthogonal experiment.And the optimization combination of height,length,and width in the experimental range was also found.The experimental results show that the anti-fouling capability of tetrahedral vortex generator is strengthened with increasing the height and the width,and decreases with increasing the length.The height and width of the tetrahedral vortex generator has a significant impact on the characteristics of the particulate fouling.The height has the greatest influence on the characteristics of the particulate fouling,the effect of the width is the second,and the influence of the length is the smallest.Tetrahedral vortex generators with height of 6 mm length of 20 mm width of 30 mm have the best anti-fouling capability within the scope of the experiments.On this basis,the influence of longitudinal spacing on Mg O particulate fouling is also studied.The asymptotic value of fouling resistance tends to decrease first and then increase with the increase of longitudinal spacing in the experimental range.The best longitudinal spacing is 80mm.At last,experiment were conducted in rectangular channel to investigate the effect of working fluid flow rate,concentration of working fluid,inlet temperature and water bath temperature on particulate fouling characteristics by means of orthogonal design.The best operating conditions in the experimental range was also found.The results show that the effect of working fluid concentration on the characteristics of fouling is the biggest,the flow velocity of working fluid is the second,the inlet temperature is the third,and the influence of the bath temperature is the least.The thermal resistance increases with the increase of the working fluid flow rate,the decrease of the working medium concentration,the decrease of the inlet temperature and the increase of the water bath temperature.The amount of fouling is the smallest under the condition of a working fluid flow rate of0.15m·s^-1,a working medium concentration of 200mg·L^-1,an inlet temperature of 23?and a water bath temperature of 50?within the scope of the experiments.