Modeling And Simulation Of Oil Particle Filtration By Three-Dimensional Knitted Air Filter

In recent years,the emission of cooking fume has become more and more serious,and its harm to human and environment has become increasingly prominent.Therefore,how to effectively remove cooking fume has been the research focus of environment protection in China.It is recommended to use a compound cooking fume purification technology,which combines two or more technologies can complement the disadvantages of different purification technologies and has great development potential for fume treating.The primary filter acts as the foremost compound of the compound purification and has a significant impact on the performance of the postpurifying components.At present,the common primary filter often has problems such as low filtration efficiency,high resistance and short service life.For this reason,a three-dimensional knitted fiber filter was designed in previous laboratory studies,which can significantly reduce the resistance and increase the oil holding capacity and this filter can be recycled.Due to its special three-dimensional structure,the filter has large oil holding capacity compared with the traditional fiber filter.In order to further improve the filtration efficiency and quality factor of this filter,geometric modeling and numerical simulation were used to research its structure parameters and complete its optimization.In the modeling of the fiber media,the three-dimensional structure of the filter material is divided into upper,middle and lower layers to establish a model.For the upper layer,the circulating unit bending loop is simplified into a loop composed of three straight fibers;for the lower fiber,the circulation unit is selected by the SEM image and simplified;for the middle layer,the long curved fiber is simplified with two straight fibers of the same lengths and inclination angle.The solid volume fraction of the model,with a deviation of 3.9%,preliminarily verified the accuracy of the geometric model.The CFD-DPM model was used to simulate the filtration performance.On the one hand,the semi-empirical formula is used for compare with the simulated date.On the out other hand,the experimental platform is built according to the relevant standards to test the filtration efficiency and pressure drop of the filter.The data was compared with the simulation results to verify the accuracy of the three-dimensional woven filter material filtration model.Through numerical simulation of filtration performance,it is found that increasing the coarse density and wale density of the upper and lower layers will improve the filtration efficiency and resistance,but will reduce the quality factor,and increase the number of monofilaments in the multifilament will improve the purification efficiency and quality factor,and reduce the diameter the monofilament will increase the quality factor.For the upper layer,the coarse density has a greater influence on the filtration performance of the filter.For the middle layer,when the inclination angle is 40°,the purification performance is optimal.Increasing the thickness of the layer will simultaneously improve the filtration efficiency and the quality factor,increase the fiber textile density per unit area,and improve the purification efficiency of the intermediate fiber layer will reduce the quality factor.The smaller the diameter of the fiber,the faster the purification efficiency increases and the higher the quality factor.