| Finned tube heat exchanger is one of the important equipment of direct air cooled condenser.Particles deposited on the outer surface of the fin tube bundle,not only affect the heat transfer efficiency of the fin and tube heat exchanger,but also play a decisive role in the safe and economic operation of the unit.By studying the deposition of particles on the outer surface of the finned tube bundles,it can provide a reliable theoretical basis for the reduction of particle deposition.In this paper,the deposition of particles on the outer surface of fin tubes is studied by numerical simulation,and the influence of the thickness of ash deposition on the heat transfer performance of fin and tube is also explored.Based on the theory of the gas-solid two phase,the numerical simulation of the deposition process of the particles in the fin tube was simulated by using Fluent software,the effects of wind velocity,solid volume fraction,fin spacing,fin thickness and fin height on the deposition rate and wear rate of the fin tubes were analyzed.The results show that the deposition rate increases with the increase of the particle deposition rate,when the wind speed is greater than 1.5m/s,the growth rate of the deposition rate decreases gradually;the deposition rate increases with the increase of solid phase volume fraction,when the solid volume fraction is larger than a certain value,the deposition rate becomes smaller,and it has a certain degree of saturation;with the increase of fin spacing,the deposition rate decreases when the wind speed is low,the deposition rate increases when the wind speed is higher;the deposition rate increases with the increase of fin thickness;but the deposition rate decreases with the increase of fin height.For the wear of finned tubes,the greater wind speed,the greater wear rate;the higher solid phase volume fraction,the higher wear rate;the wear rate decreases with the increase of fin pitch;the wear rate increases with the increase of fin thickness;the fin height is less than19 mm,the wear rate increases,the fin height is greater than 19 mm,and the wear rate decreases.For the case of uniform ash deposition on the fin tubes,the effect of the thickness of ash deposition on the heat transfer performance of fin and tube is analyzed,the characteristics of heat transfer and flow before and after the fin tubes are obtained.The results show that the convective heat transfer coefficient,heat transfer coefficient and pressure drop are gradually increased with the increase of the face velocity,and the friction coefficient decreases gradually;at the same wind speed,the convective heat transfer coefficient increases slightly,the pressure drop and friction coefficient increase gradually,and the heat transfer coefficient decreases gradually with the increase of the thickness of the plot.With the increase of Re,the friction coefficient becomes smaller,and the Nu increases;the greater the thickness of the accumulation,the friction coefficient increases,the Nu becomes smaller,and the heat transfer performance of the finned tube is reduced.With the increase of the thickness of the pipe,the heat transfer performance of the finned tube is decreased. |
